Next: Introduction [Contents][Index]
_close_r—Reentrant version of close_execve_r—Reentrant version of execve_fork_r—Reentrant version of fork_wait_r—Reentrant version of wait_fstat_r—Reentrant version of fstat_link_r—Reentrant version of link_lseek_r—Reentrant version of lseek_open_r—Reentrant version of open_read_r—Reentrant version of read_sbrk_r—Reentrant version of sbrk_kill_r—Reentrant version of kill_getpid_r—Reentrant version of getpid_stat_r—Reentrant version of stat_times_r—Reentrant version of times_unlink_r—Reentrant version of unlink_write_r—Reentrant version of write_Exit—end program execution with no cleanup processinga64l, l64a—convert between radix-64 ASCII string and longabort—abnormal termination of a programabs—integer absolute value (magnitude)assert—macro for debugging diagnosticsatexit—request execution of functions at program exitatof, atoff—string to double or floatatoi, atol—string to integeratoll—convert a string to a long long integerbsearch—binary searchcalloc—allocate space for arraysdiv—divide two integersecvt, ecvtf, fcvt, fcvtf—double or float to stringgcvt, gcvtf—format double or float as stringecvtbuf, fcvtbuf—double or float to string__env_lock, __env_unlock—lock environ variableexit—end program executiongetenv—look up environment variableitoa—integer to stringlabs—long integer absolute valueldiv—divide two long integersllabs—compute the absolute value of an long long integer.lldiv—divide two long long integersmalloc, realloc, free—manage memorymallinfo, malloc_stats, mallopt—malloc support__malloc_lock, __malloc_unlock—lock malloc poolmblen—minimal multibyte length functionmbsrtowcs, mbsnrtowcs—convert a character string to a wide-character stringmbstowcs—minimal multibyte string to wide char convertermbtowc—minimal multibyte to wide char converteron_exit—request execution of function with argument at program exitqsort—sort an arrayrand, srand—pseudo-random numbersrandom, srandom—pseudo-random numbersrand48, drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48, lcong48—pseudo-random number generators and initialization routinesrpmatch—determine whether response to question is affirmative or negativestrtod, strtof, strtold, strtod_l, strtof_l, strtold_l—string to double or floatstrtol, strtol_l—string to longstrtoll, strtoll_l—string to long longstrtoul, strtoul_l—string to unsigned longstrtoull, strtoull_l—string to unsigned long longwcsrtombs, wcsnrtombs—convert a wide-character string to a character stringwcstod, wcstof, wcstold, wcstod_l, wcstof_l, wcstold_l—wide char string to double or floatwcstol, wcstol_l—wide string to longwcstoll, wcstoll_l—wide string to long longwcstoul, wcstoul_l—wide string to unsigned longwcstoull, wcstoull_l—wide string to unsigned long longsystem—execute command stringutoa—unsigned integer to stringwcstombs—minimal wide char string to multibyte string converterwctomb—minimal wide char to multibyte converterisalnum, isalnum_l—alphanumeric character predicateisalpha, isalpha_l—alphabetic character predicateisascii, isascii_l—ASCII character predicateisblank, isblank_l—blank character predicateiscntrl, iscntrl_l—control character predicateisdigit, isdigit_l—decimal digit predicateislower, islower_l—lowercase character predicateisprint, isgraph, isprint_l, isgraph_l—printable character predicatesispunct, ispunct_l—punctuation character predicateisspace, isspace_l—whitespace character predicateisupper, isupper_l—uppercase character predicateisxdigit, isxdigit_l—hexadecimal digit predicatetoascii, toascii_l—force integers to ASCII rangetolower, tolower_l—translate characters to lowercasetoupper, toupper_l—translate characters to uppercaseiswalnum, iswalnum_l—alphanumeric wide character testiswalpha, iswalpha_l—alphabetic wide character testiswcntrl, iswcntrl_l—control wide character testiswblank, iswblank_l—blank wide character testiswdigit, iswdigit_l—decimal digit wide character testiswgraph, iswgraph_l—graphic wide character testiswlower, iswlower_l—lowercase wide character testiswprint, iswprint_l—printable wide character testiswpunct, iswpunct_l—punctuation wide character testiswspace, iswspace_l—whitespace wide character testiswupper, iswupper_l—uppercase wide character testiswxdigit, iswxdigit_l—hexadecimal digit wide character testiswctype, iswctype_l—extensible wide-character testwctype, wctype_l—get wide-character classification typetowlower, towlower_l—translate wide characters to lowercasetowupper, towupper_l—translate wide characters to uppercasetowctrans, towctrans_l—extensible wide-character translationwctrans, wctrans_l—get wide-character translation typeclearerr, clearerr_unlocked—clear file or stream error indicatordiprintf, vdiprintf—print to a file descriptor (integer only)dprintf, vdprintf—print to a file descriptorfclose—close a filefcloseall—close all filesfdopen—turn open file into a streamfeof, feof_unlocked—test for end of fileferror, ferror_unlocked—test whether read/write error has occurredfflush, fflush_unlocked—flush buffered file outputfgetc, fgetc_unlocked—get a character from a file or streamfgetpos—record position in a stream or filefgets, fgets_unlocked—get character string from a file or streamfgetwc, getwc, fgetwc_unlocked, getwc_unlocked—get a wide character from a file or streamfgetws, fgetws_unlocked—get wide character string from a file or streamfileno, fileno_unlocked—return file descriptor associated with streamfmemopen—open a stream around a fixed-length stringfopen—open a filefopencookie—open a stream with custom callbacksfpurge—discard pending file I/Ofputc, fputc_unlocked—write a character on a stream or filefputs, fputs_unlocked—write a character string in a file or streamfputwc, putwc, fputwc_unlocked, putwc_unlocked—write a wide character on a stream or filefputws, fputws_unlocked—write a wide character string in a file or streamfread, fread_unlocked—read array elements from a filefreopen—open a file using an existing file descriptorfseek, fseeko—set file position__fsetlocking—set or query locking mode on FILE streamfsetpos—restore position of a stream or fileftell, ftello—return position in a stream or filefunopen, fropen, fwopen—open a stream with custom callbacksfwide—set and determine the orientation of a FILE streamfwrite, fwrite_unlocked—write array elementsgetc—read a character (macro)getc_unlocked—non-thread-safe version of getc (macro)getchar—read a character (macro)getchar_unlocked—non-thread-safe version of getchar (macro)getdelim—read a line up to a specified line delimitergetline—read a line from a filegets—get character string (obsolete, use fgets instead)getw—read a word (int)getwchar, getwchar_unlocked—read a wide character from standard inputmktemp, mkstemp, mkostemp, mkstemps,open_memstream, open_wmemstream—open a write stream around an arbitrary-length stringperror—print an error message on standard errorputc—write a character (macro)putc_unlocked—non-thread-safe version of putc (macro)putchar—write a character (macro)putchar_unlocked—non-thread-safe version of putchar (macro)puts—write a character stringputw—write a word (int)putwchar, putwchar_unlocked—write a wide character to standard outputremove—delete a file’s namerename—rename a filerewind—reinitialize a file or streamsetbuf—specify full buffering for a file or streamsetbuffer—specify full buffering for a file or stream with sizesetlinebuf—specify line buffering for a file or streamsetvbuf—specify file or stream bufferingsiprintf, fiprintf, iprintf, sniprintf, asiprintf, asniprintf—format output (integer only)siscanf, fiscanf, iscanf—scan and format non-floating inputsprintf, fprintf, printf, snprintf, asprintf, asnprintf—format outputsscanf, fscanf, scanf—scan and format inputstdio_ext,__fbufsize,__fpending,__flbf,__freadable,__fwritable,__freading,__fwriting—access internals of FILE structureswprintf, fwprintf, wprintf—wide character format outputswscanf, fwscanf, wscanf—scan and format wide character inputtmpfile—create a temporary filetmpnam, tempnam—name for a temporary fileungetc—push data back into a streamungetwc—push wide character data back into a streamvfprintf, vprintf, vsprintf, vsnprintf, vasprintf, vasnprintf—format argument listvfscanf, vscanf, vsscanf—format argument listvfwprintf, vwprintf, vswprintf—wide character format argument listvfwscanf, vwscanf, vswscanf—scan and format argument list from wide character inputviprintf, vfiprintf, vsiprintf, vsniprintf, vasiprintf, vasniprintf—format argument list (integer only)viscanf, vfiscanf, vsiscanf—format argument listfdopen64—turn open large file into a streamfopen64—open a large filefreopen64—open a large file using an existing file descriptorftello64—return position in a stream or filefseeko64—set file position for large filefgetpos64—record position in a large stream or filefsetpos64—restore position of a large stream or filetmpfile64—create a large temporary filebcmp—compare two memory areasbcopy—copy memory regionsbzero—initialize memory to zeroindex—search for character in stringmemccpy—copy memory regions with end-token checkmemchr—find character in memorymemcmp—compare two memory areasmemcpy—copy memory regionsmemmem—find memory segmentmemmove—move possibly overlapping memorymempcpy—copy memory regions and return end pointermemrchr—reverse search for character in memorymemset—set an area of memoryrawmemchr—find character in memoryrindex—reverse search for character in stringstpcpy—copy string returning a pointer to its endstpncpy—counted copy string returning a pointer to its endstrcasecmp—case-insensitive character string comparestrcasestr—case-insensitive character string searchstrcat—concatenate stringsstrchr—search for character in stringstrchrnul—search for character in stringstrcmp—character string comparestrcoll—locale-specific character string comparestrcpy—copy stringstrcspn—count characters not in stringstrerror, strerror_l—convert error number to stringstrerror_r—convert error number to string and copy to bufferstrlen—character string lengthstrlwr—force string to lowercasestrncasecmp—case-insensitive character string comparestrncat—concatenate stringsstrncmp—character string comparestrncpy—counted copy stringstrnstr—find string segmentstrnlen—character string lengthstrpbrk—find characters in stringstrrchr—reverse search for character in stringstrsignal—convert signal number to stringstrspn—find initial matchstrstr—find string segmentstrtok, strtok_r, strsep—get next token from a stringstrupr—force string to uppercasestrverscmp—version string comparestrxfrm—transform stringswab—swap adjacent byteswcscasecmp—case-insensitive wide character string comparewcsdup—wide character string duplicatewcsncasecmp—case-insensitive wide character string comparewmemchr—find a wide character in memorywmemcmp—compare wide characters in memorywmemcpy—copy wide characters in memorywmemmove—copy wide characters in memory with overlapping areaswmempcpy—copy wide characters in memory and return end pointerwmemset—set wide characters in memorywcscat—concatenate two wide-character stringswcschr—wide-character string scanning operationwcscmp—compare two wide-character stringswcscoll—locale-specific wide-character string comparewcscpy—copy a wide-character stringwcpcpy—copy a wide-character string returning a pointer to its endwcscspn—get length of a complementary wide substringwcsftime—convert date and time to a formatted wide-character stringwcslcat—concatenate wide-character strings to specified lengthwcslcpy—copy a wide-character string to specified lengthwcslen—get wide-character string lengthwcsncat—concatenate part of two wide-character stringswcsncmp—compare part of two wide-character stringswcsncpy—copy part of a wide-character stringwcpncpy—copy part of a wide-character string returning a pointer to its endwcsnlen—get fixed-size wide-character string lengthwcspbrk—-scan wide-character string for a wide-character codewcsrchr—wide-character string scanning operationwcsspn—get length of a wide substringwcsstr—find a wide-character substringwcstok—get next token from a stringwcswidth—number of column positions of a wide-character stringwcsxfrm—locale-specific wide-character string transformationwcwidth—number of column positions of a wide-character codeasctime—format time as stringclock—cumulative processor timectime—convert time to local and format as stringdifftime—subtract two timesgmtime—convert time to UTC traditional formlocaltime—convert time to local representationmktime—convert time to arithmetic representationstrftime, strftime_l—convert date and time to a formatted stringtime—get current calendar time (as single number)__tz_lock, __tz_unlock—lock time zone global variablestzset—set timezone characteristics from TZ environment variableffs—find first bit set in a word__retarget_lock_init, __retarget_lock_init_recursive, __retarget_lock_close, __retarget_lock_close_recursive, __retarget_lock_acquire, __retarget_lock_acquire_recursive, __retarget_lock_try_acquire, __retarget_lock_try_acquire_recursive, __retarget_lock_release, __retarget_lock_release_recursive—locking routinesunctrl—get printable representation of a charactericonv, iconv_open, iconv_close—charset conversion routinesNext: System Calls, Previous: The Red Hat newlib C Library, Up: The Red Hat newlib C Library [Contents][Index]
This reference manual describes the functions provided by the Red Hat “newlib” version of the standard ANSI C library. This document is not intended as an overview or a tutorial for the C library. Each library function is listed with a synopsis of its use, a brief description, return values (including error handling), and portability issues.
Some of the library functions depend on support from the underlying operating system and may not be available on every platform. For embedded systems in particular, many of these underlying operating system services may not be available or may not be fully functional. The specific operating system subroutines required for a particular library function are listed in the “Portability” section of the function description. See System Calls, for a description of the relevant operating system calls.
Next: Standard Utility Functions (stdlib.h), Previous: Introduction, Up: The Red Hat newlib C Library [Contents][Index]
The C subroutine library depends on a handful of subroutine calls for operating system services. If you use the C library on a system that complies with the POSIX.1 standard (also known as IEEE 1003.1), most of these subroutines are supplied with your operating system.
If some of these subroutines are not provided with your system—in
the extreme case, if you are developing software for a “bare board”
system, without an OS—you will at least need to provide do-nothing
stubs (or subroutines with minimal functionality) to allow your
programs to link with the subroutines in libc.a.
Next: Reentrant covers for OS subroutines, Up: System Calls [Contents][Index]
This is the complete set of system definitions (primarily subroutines)
required; the examples shown implement the minimal functionality
required to allow libc to link, and fail gracefully where OS
services are not available.
Graceful failure is permitted by returning an error code. A minor
complication arises here: the C library must be compatible with
development environments that supply fully functional versions of these
subroutines. Such environments usually return error codes in a global
errno. However, the Red Hat newlib C library provides a macro
definition for errno in the header file errno.h, as part
of its support for reentrant routines (see Reentrancy).
The bridge between these two interpretations of errno is
straightforward: the C library routines with OS interface calls
capture the errno values returned globally, and record them in
the appropriate field of the reentrancy structure (so that you can query
them using the errno macro from errno.h).
This mechanism becomes visible when you write stub routines for OS interfaces. You must include errno.h, then disable the macro, like this:
#include <errno.h> #undef errno extern int errno;
The examples in this chapter include this treatment of errno.
_exit ¶Exit a program without cleaning up files. If your system doesn’t
provide this, it is best to avoid linking with subroutines that require
it (exit, system).
close ¶Close a file. Minimal implementation:
int close(int file) {
return -1;
}
environ ¶A pointer to a list of environment variables and their values. For a minimal environment, this empty list is adequate:
char *__env[1] = { 0 };
char **environ = __env;
execve ¶Transfer control to a new process. Minimal implementation (for a system without processes):
#include <errno.h>
#undef errno
extern int errno;
int execve(char *name, char **argv, char **env) {
errno = ENOMEM;
return -1;
}
fork ¶Create a new process. Minimal implementation (for a system without processes):
#include <errno.h>
#undef errno
extern int errno;
int fork(void) {
errno = EAGAIN;
return -1;
}
fstat ¶Status of an open file. For consistency with other minimal implementations in these examples, all files are regarded as character special devices. The sys/stat.h header file required is distributed in the include subdirectory for this C library.
#include <sys/stat.h>
int fstat(int file, struct stat *st) {
st->st_mode = S_IFCHR;
return 0;
}
getpid ¶Process-ID; this is sometimes used to generate strings unlikely to conflict with other processes. Minimal implementation, for a system without processes:
int getpid(void) {
return 1;
}
isatty ¶Query whether output stream is a terminal. For consistency with the
other minimal implementations, which only support output to
stdout, this minimal implementation is suggested:
int isatty(int file) {
return 1;
}
kill ¶Send a signal. Minimal implementation:
#include <errno.h>
#undef errno
extern int errno;
int kill(int pid, int sig) {
errno = EINVAL;
return -1;
}
link ¶Establish a new name for an existing file. Minimal implementation:
#include <errno.h>
#undef errno
extern int errno;
int link(char *old, char *new) {
errno = EMLINK;
return -1;
}
lseek ¶Set position in a file. Minimal implementation:
int lseek(int file, int ptr, int dir) {
return 0;
}
open ¶Open a file. Minimal implementation:
int open(const char *name, int flags, int mode) {
return -1;
}
read ¶Read from a file. Minimal implementation:
int read(int file, char *ptr, int len) {
return 0;
}
sbrk ¶Increase program data space. As malloc and related functions
depend on this, it is useful to have a working implementation. The
following suffices for a standalone system; it exploits the symbol
_end automatically defined by the GNU linker.
caddr_t sbrk(int incr) {
extern char _end; /* Defined by the linker */
static char *heap_end;
char *prev_heap_end;
if (heap_end == 0) {
heap_end = &_end;
}
prev_heap_end = heap_end;
if (heap_end + incr > stack_ptr) {
write (1, "Heap and stack collision\n", 25);
abort ();
}
heap_end += incr;
return (caddr_t) prev_heap_end;
}
stat ¶Status of a file (by name). Minimal implementation:
int stat(char *file, struct stat *st) {
st->st_mode = S_IFCHR;
return 0;
}
times ¶Timing information for current process. Minimal implementation:
int times(struct tms *buf) {
return -1;
}
unlink ¶Remove a file’s directory entry. Minimal implementation:
#include <errno.h>
#undef errno
extern int errno;
int unlink(char *name) {
errno = ENOENT;
return -1;
}
wait ¶Wait for a child process. Minimal implementation:
#include <errno.h>
#undef errno
extern int errno;
int wait(int *status) {
errno = ECHILD;
return -1;
}
write ¶Write to a file. libc subroutines will use this
system routine for output to all files, including
stdout—so if you need to generate any output, for example to a
serial port for debugging, you should make your minimal write
capable of doing this. The following minimal implementation is an
incomplete example; it relies on a outbyte subroutine (not
shown; typically, you must write this in assembler from examples
provided by your hardware manufacturer) to actually perform the output.
int write(int file, char *ptr, int len) {
int todo;
for (todo = 0; todo < len; todo++) {
outbyte (*ptr++);
}
return len;
}
Previous: Definitions for OS interface, Up: System Calls [Contents][Index]
Since the system subroutines are used by other library routines that
require reentrancy, libc.a provides cover routines (for example,
the reentrant version of fork is _fork_r). These cover
routines are consistent with the other reentrant subroutines in this
library, and achieve reentrancy by using a reserved global data block
(see Reentrancy).
_close_r—Reentrant version of close_execve_r—Reentrant version of execve_fork_r—Reentrant version of fork_wait_r—Reentrant version of wait_fstat_r—Reentrant version of fstat_link_r—Reentrant version of link_lseek_r—Reentrant version of lseek_open_r—Reentrant version of open_read_r—Reentrant version of read_sbrk_r—Reentrant version of sbrk_kill_r—Reentrant version of kill_getpid_r—Reentrant version of getpid_stat_r—Reentrant version of stat_times_r—Reentrant version of times_unlink_r—Reentrant version of unlink_write_r—Reentrant version of write
Next: _execve_r—Reentrant version of execve, Up: Reentrant covers for OS subroutines [Contents][Index]
_close_r—Reentrant version of closeSynopsis
#include <reent.h> int _close_r(struct _reent *ptr, int fd);
Description
This is a reentrant version of close. It
takes a pointer to the global data block, which holds
errno.
Next: _fork_r—Reentrant version of fork, Previous: _close_r—Reentrant version of close, Up: Reentrant covers for OS subroutines [Contents][Index]
_execve_r—Reentrant version of execveSynopsis
#include <reent.h>
int _execve_r(struct _reent *ptr, const char *name,
char *const argv[], char *const env[]);
Description
This is a reentrant version of execve. It
takes a pointer to the global data block, which holds
errno.
Next: _wait_r—Reentrant version of wait, Previous: _execve_r—Reentrant version of execve, Up: Reentrant covers for OS subroutines [Contents][Index]
_fork_r—Reentrant version of forkSynopsis
#include <reent.h> int _fork_r(struct _reent *ptr);
Description
This is a reentrant version of fork. It
takes a pointer to the global data block, which holds
errno.
Next: _fstat_r—Reentrant version of fstat, Previous: _fork_r—Reentrant version of fork, Up: Reentrant covers for OS subroutines [Contents][Index]
_wait_r—Reentrant version of waitSynopsis
#include <reent.h> int _wait_r(struct _reent *ptr, int *status);
Description
This is a reentrant version of wait. It
takes a pointer to the global data block, which holds
errno.
Next: _link_r—Reentrant version of link, Previous: _wait_r—Reentrant version of wait, Up: Reentrant covers for OS subroutines [Contents][Index]
_fstat_r—Reentrant version of fstatSynopsis
#include <reent.h>
int _fstat_r(struct _reent *ptr,
int fd, struct stat *pstat);
Description
This is a reentrant version of fstat. It
takes a pointer to the global data block, which holds
errno.
Next: _lseek_r—Reentrant version of lseek, Previous: _fstat_r—Reentrant version of fstat, Up: Reentrant covers for OS subroutines [Contents][Index]
_link_r—Reentrant version of linkSynopsis
#include <reent.h>
int _link_r(struct _reent *ptr,
const char *old, const char *new);
Description
This is a reentrant version of link. It
takes a pointer to the global data block, which holds
errno.
Next: _open_r—Reentrant version of open, Previous: _link_r—Reentrant version of link, Up: Reentrant covers for OS subroutines [Contents][Index]
_lseek_r—Reentrant version of lseekSynopsis
#include <reent.h>
off_t _lseek_r(struct _reent *ptr,
int fd, off_t pos, int whence);
Description
This is a reentrant version of lseek. It
takes a pointer to the global data block, which holds
errno.
Next: _read_r—Reentrant version of read, Previous: _lseek_r—Reentrant version of lseek, Up: Reentrant covers for OS subroutines [Contents][Index]
_open_r—Reentrant version of openSynopsis
#include <reent.h>
int _open_r(struct _reent *ptr,
const char *file, int flags, int mode);
Description
This is a reentrant version of open. It
takes a pointer to the global data block, which holds
errno.
Next: _sbrk_r—Reentrant version of sbrk, Previous: _open_r—Reentrant version of open, Up: Reentrant covers for OS subroutines [Contents][Index]
_read_r—Reentrant version of readSynopsis
#include <reent.h>
_ssize_t _read_r(struct _reent *ptr,
int fd, void *buf, size_t cnt);
Description
This is a reentrant version of read. It
takes a pointer to the global data block, which holds
errno.
Next: _kill_r—Reentrant version of kill, Previous: _read_r—Reentrant version of read, Up: Reentrant covers for OS subroutines [Contents][Index]
_sbrk_r—Reentrant version of sbrkSynopsis
#include <reent.h> void *_sbrk_r(struct _reent *ptr, ptrdiff_t incr);
Description
This is a reentrant version of sbrk. It
takes a pointer to the global data block, which holds
errno.
Next: _getpid_r—Reentrant version of getpid, Previous: _sbrk_r—Reentrant version of sbrk, Up: Reentrant covers for OS subroutines [Contents][Index]
_kill_r—Reentrant version of killSynopsis
#include <reent.h> int _kill_r(struct _reent *ptr, int pid, int sig);
Description
This is a reentrant version of kill. It
takes a pointer to the global data block, which holds
errno.
Next: _stat_r—Reentrant version of stat, Previous: _kill_r—Reentrant version of kill, Up: Reentrant covers for OS subroutines [Contents][Index]
_getpid_r—Reentrant version of getpidSynopsis
#include <reent.h> int _getpid_r(struct _reent *ptr);
Description
This is a reentrant version of getpid. It
takes a pointer to the global data block, which holds
errno.
We never need errno, of course, but for consistency we
still must have the reentrant pointer argument.
Next: _times_r—Reentrant version of times, Previous: _getpid_r—Reentrant version of getpid, Up: Reentrant covers for OS subroutines [Contents][Index]
_stat_r—Reentrant version of statSynopsis
#include <reent.h>
int _stat_r(struct _reent *ptr,
const char *file, struct stat *pstat);
Description
This is a reentrant version of stat. It
takes a pointer to the global data block, which holds
errno.
Next: _unlink_r—Reentrant version of unlink, Previous: _stat_r—Reentrant version of stat, Up: Reentrant covers for OS subroutines [Contents][Index]
_times_r—Reentrant version of timesSynopsis
#include <reent.h> #include <sys/times.h> clock_t _times_r(struct _reent *ptr, struct tms *ptms);
Description
This is a reentrant version of times. It
takes a pointer to the global data block, which holds
errno.
Next: _write_r—Reentrant version of write, Previous: _times_r—Reentrant version of times, Up: Reentrant covers for OS subroutines [Contents][Index]
_unlink_r—Reentrant version of unlinkSynopsis
#include <reent.h> int _unlink_r(struct _reent *ptr, const char *file);
Description
This is a reentrant version of unlink. It
takes a pointer to the global data block, which holds
errno.
Previous: _unlink_r—Reentrant version of unlink, Up: Reentrant covers for OS subroutines [Contents][Index]
_write_r—Reentrant version of writeSynopsis
#include <reent.h>
_ssize_t _write_r(struct _reent *ptr,
int fd, const void *buf, size_t cnt);
Description
This is a reentrant version of write. It
takes a pointer to the global data block, which holds
errno.
Next: Character Type Macros and Functions (ctype.h), Previous: System Calls, Up: The Red Hat newlib C Library [Contents][Index]
This chapter groups utility functions useful in a variety of programs. The corresponding declarations are in the header file stdlib.h.
_Exit—end program execution with no cleanup processinga64l, l64a—convert between radix-64 ASCII string and longabort—abnormal termination of a programabs—integer absolute value (magnitude)assert—macro for debugging diagnosticsatexit—request execution of functions at program exitatof, atoff—string to double or floatatoi, atol—string to integeratoll—convert a string to a long long integerbsearch—binary searchcalloc—allocate space for arraysdiv—divide two integersecvt, ecvtf, fcvt, fcvtf—double or float to stringgcvt, gcvtf—format double or float as stringecvtbuf, fcvtbuf—double or float to string__env_lock, __env_unlock—lock environ variableexit—end program executiongetenv—look up environment variableitoa—integer to stringlabs—long integer absolute valueldiv—divide two long integersllabs—compute the absolute value of an long long integer.lldiv—divide two long long integersmalloc, realloc, free—manage memorymallinfo, malloc_stats, mallopt—malloc support__malloc_lock, __malloc_unlock—lock malloc poolmblen—minimal multibyte length functionmbsrtowcs, mbsnrtowcs—convert a character string to a wide-character stringmbstowcs—minimal multibyte string to wide char convertermbtowc—minimal multibyte to wide char converteron_exit—request execution of function with argument at program exitqsort—sort an arrayrand, srand—pseudo-random numbersrandom, srandom—pseudo-random numbersrand48, drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48, lcong48—pseudo-random number generators and initialization routinesrpmatch—determine whether response to question is affirmative or negativestrtod, strtof, strtold, strtod_l, strtof_l, strtold_l—string to double or floatstrtol, strtol_l—string to longstrtoll, strtoll_l—string to long longstrtoul, strtoul_l—string to unsigned longstrtoull, strtoull_l—string to unsigned long longwcsrtombs, wcsnrtombs—convert a wide-character string to a character stringwcstod, wcstof, wcstold, wcstod_l, wcstof_l, wcstold_l—wide char string to double or floatwcstol, wcstol_l—wide string to longwcstoll, wcstoll_l—wide string to long longwcstoul, wcstoul_l—wide string to unsigned longwcstoull, wcstoull_l—wide string to unsigned long longsystem—execute command stringutoa—unsigned integer to stringwcstombs—minimal wide char string to multibyte string converterwctomb—minimal wide char to multibyte converter
Next: a64l, l64a—convert between radix-64 ASCII string and long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
_Exit—end program execution with no cleanup processingSynopsis
#include <stdlib.h> void _Exit(int code);
Description
Use _Exit to return control from a program to the host operating
environment. Use the argument code to pass an exit status to the
operating environment: two particular values, EXIT_SUCCESS and
EXIT_FAILURE, are defined in ‘stdlib.h’ to indicate success or
failure in a portable fashion.
_Exit differs from exit in that it does not run any
application-defined cleanup functions registered with atexit and
it does not clean up files and streams. It is identical to _exit.
Returns
_Exit does not return to its caller.
Portability
_Exit is defined by the C99 standard.
Supporting OS subroutines required: _exit.
Next: abort—abnormal termination of a program, Previous: _Exit—end program execution with no cleanup processing, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
a64l, l64a—convert between radix-64 ASCII string and longSynopsis
#include <stdlib.h> long a64l(const char *input); char *l64a(long input);
Description
Conversion is performed between long and radix-64 characters. The
l64a routine transforms up to 32 bits of input value starting from
least significant bits to the most significant bits. The input value
is split up into a maximum of 5 groups of 6 bits and possibly one
group of 2 bits (bits 31 and 30).
Each group of 6 bits forms a value from 0–63 which is translated into a character as follows:
When the remaining bits are zero or all bits have been translated, a null terminator is appended to the string. An input value of 0 results in the empty string.
The a64l function performs the reverse translation. Each
character is used to generate a 6-bit value for up to 30 bits and then
a 2-bit value to complete a 32-bit result. The null terminator means
that the remaining digits are 0. An empty input string or NULL string
results in 0L. An invalid string results in undefined behavior. If
the size of a long is greater than 32 bits, the result is sign-extended.
Returns
l64a returns a null-terminated string of 0 to 6 characters.
a64l returns the 32-bit translated value from the input character string.
Portability
l64a and a64l are non-ANSI and are defined by the Single Unix Specification.
Supporting OS subroutines required: None.
Next: abs—integer absolute value (magnitude), Previous: a64l, l64a—convert between radix-64 ASCII string and long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
abort—abnormal termination of a programSynopsis
#include <stdlib.h> void abort(void);
Description
Use abort to signal that your program has detected a condition it
cannot deal with. Normally, abort ends your program’s execution.
Before terminating your program, abort raises the exception SIGABRT
(using ‘raise(SIGABRT)’). If you have used signal to register
an exception handler for this condition, that handler has the
opportunity to retain control, thereby avoiding program termination.
In this implementation, abort does not perform any stream- or
file-related cleanup (the host environment may do so; if not, you can
arrange for your program to do its own cleanup with a SIGABRT
exception handler).
Returns
abort does not return to its caller.
Portability
ANSI C requires abort.
Supporting OS subroutines required: _exit and optionally, write.
Next: assert—macro for debugging diagnostics, Previous: abort—abnormal termination of a program, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
abs—integer absolute value (magnitude)Synopsis
#include <stdlib.h> int abs(int i);
Description
abs returns
the absolute value of i (also called the magnitude
of i). That is, if i is negative, the result is the opposite
of i, but if i is nonnegative the result is i.
The similar function labs uses and returns long rather than int values.
Returns
The result is a nonnegative integer.
Portability
abs is ANSI.
No supporting OS subroutines are required.
Next: atexit—request execution of functions at program exit, Previous: abs—integer absolute value (magnitude), Up: Standard Utility Functions (stdlib.h) [Contents][Index]
assert—macro for debugging diagnosticsSynopsis
#include <assert.h> void assert(int expression);
Description
Use this macro to embed debuggging diagnostic statements in
your programs. The argument expression should be an
expression which evaluates to true (nonzero) when your program
is working as you intended.
When expression evaluates to false (zero), assert
calls abort, after first printing a message showing what
failed and where:
Assertion failed: expression, file filename, line lineno, function: func
If the name of the current function is not known (for example, when using a C89 compiler that does not understand __func__), the function location is omitted.
The macro is defined to permit you to turn off all uses of
assert at compile time by defining NDEBUG as a
preprocessor variable. If you do this, the assert macro
expands to
(void(0))
Returns
assert does not return a value.
Portability
The assert macro is required by ANSI, as is the behavior
when NDEBUG is defined.
Supporting OS subroutines required (only if enabled): close, fstat,
getpid, isatty, kill, lseek, read, sbrk, write.
Next: atof, atoff—string to double or float, Previous: assert—macro for debugging diagnostics, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
atexit—request execution of functions at program exitSynopsis
#include <stdlib.h> int atexit (void (*function)(void));
Description
You can use atexit to enroll functions in a list of functions that
will be called when your program terminates normally. The argument is
a pointer to a user-defined function (which must not require arguments and
must not return a result).
The functions are kept in a LIFO stack; that is, the last function
enrolled by atexit will be the first to execute when your program
exits.
There is no built-in limit to the number of functions you can enroll
in this list; however, after every group of 32 functions is enrolled,
atexit will call malloc to get space for the next part of the
list. The initial list of 32 functions is statically allocated, so
you can always count on at least that many slots available.
Returns
atexit returns 0 if it succeeds in enrolling your function,
-1 if it fails (possible only if no space was available for
malloc to extend the list of functions).
Portability
atexit is required by the ANSI standard, which also specifies that
implementations must support enrolling at least 32 functions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: atoi, atol—string to integer, Previous: atexit—request execution of functions at program exit, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
atof, atoff—string to double or floatSynopsis
#include <stdlib.h> double atof(const char *s); float atoff(const char *s);
Description
atof converts the initial portion of a string to a double.
atoff converts the initial portion of a string to a float.
The functions parse the character string s, locating a substring which can be converted to a floating-point value. The substring must match the format:
[+|-]digits[.][digits][(e|E)[+|-]digits]
The substring converted is the longest initial
fragment of s that has the expected format, beginning with
the first non-whitespace character. The substring
is empty if str is empty, consists entirely
of whitespace, or if the first non-whitespace character is
something other than +, -, ., or a digit.
atof(s) is implemented as strtod(s, NULL).
atoff(s) is implemented as strtof(s, NULL).
Returns
atof returns the converted substring value, if any, as a
double; or 0.0, if no conversion could be performed.
If the correct value is out of the range of representable values, plus
or minus HUGE_VAL is returned, and ERANGE is stored in
errno.
If the correct value would cause underflow, 0.0 is returned
and ERANGE is stored in errno.
atoff obeys the same rules as atof, except that it
returns a float.
Portability
atof is ANSI C. atof, atoi, and atol are subsumed by strod
and strol, but are used extensively in existing code. These functions are
less reliable, but may be faster if the argument is verified to be in a valid
range.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: atoll—convert a string to a long long integer, Previous: atof, atoff—string to double or float, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
atoi, atol—string to integerSynopsis
#include <stdlib.h> int atoi(const char *s); long atol(const char *s); int _atoi_r(struct _reent *ptr, const char *s); long _atol_r(struct _reent *ptr, const char *s);
Description
atoi converts the initial portion of a string to an int.
atol converts the initial portion of a string to a long.
atoi(s) is implemented as (int)strtol(s, NULL, 10).
atol(s) is implemented as strtol(s, NULL, 10).
_atoi_r and _atol_r are reentrant versions of atoi and
atol respectively, passing the reentrancy struct pointer.
Returns
The functions return the converted value, if any. If no conversion was
made, 0 is returned.
Portability
atoi, atol are ANSI.
No supporting OS subroutines are required.
Next: bsearch—binary search, Previous: atoi, atol—string to integer, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
atoll—convert a string to a long long integerSynopsis
#include <stdlib.h> long long atoll(const char *str); long long _atoll_r(struct _reent *ptr, const char *str);
Description
The function atoll converts the initial portion of the string
pointed to by *str to a type long long. A call to
atoll(str) in this implementation is equivalent to
strtoll(str, (char **)NULL, 10) including behavior on error.
The alternate function _atoll_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
The converted value.
Portability
atoll is ISO 9899 (C99) and POSIX 1003.1-2001 compatable.
No supporting OS subroutines are required.
Next: calloc—allocate space for arrays, Previous: atoll—convert a string to a long long integer, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
bsearch—binary searchSynopsis
#include <stdlib.h>
void *bsearch(const void *key, const void *base,
size_t nmemb, size_t size,
int (*compar)(const void *, const void *));
Description
bsearch searches an array beginning at base for any element
that matches key, using binary search. nmemb is the element
count of the array; size is the size of each element.
The array must be sorted in ascending order with respect to the
comparison function compar (which you supply as the last argument of
bsearch).
You must define the comparison function (*compar) to have two
arguments; its result must be negative if the first argument is
less than the second, zero if the two arguments match, and
positive if the first argument is greater than the second (where
“less than” and “greater than” refer to whatever arbitrary
ordering is appropriate).
Returns
Returns a pointer to an element of array that matches key. If
more than one matching element is available, the result may point to
any of them.
Portability
bsearch is ANSI.
No supporting OS subroutines are required.
Next: div—divide two integers, Previous: bsearch—binary search, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
calloc—allocate space for arraysSynopsis
#include <stdlib.h> void *calloc(size_t n, size_t s); void *_calloc_r(void *reent, size_t n, size_t s);
Description
Use calloc to request a block of memory sufficient to hold an
array of n elements, each of which has size s.
The memory allocated by calloc comes out of the same memory pool
used by malloc, but the memory block is initialized to all zero
bytes. (To avoid the overhead of initializing the space, use
malloc instead.)
The alternate function _calloc_r is reentrant.
The extra argument reent is a pointer to a reentrancy structure.
Returns
If successful, a pointer to the newly allocated space.
If unsuccessful, NULL.
Portability
calloc is ANSI.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: ecvt, ecvtf, fcvt, fcvtf—double or float to string, Previous: calloc—allocate space for arrays, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
div—divide two integersSynopsis
#include <stdlib.h> div_t div(int n, int d);
Description
Divide
n/d,
returning quotient and remainder as two integers in a structure div_t.
Returns
The result is represented with the structure
typedef struct
{
int quot;
int rem;
} div_t;
where the quot field represents the quotient, and rem the
remainder. For nonzero d, if ‘r = div(n,d);’ then
n equals ‘r.rem + d*r.quot’.
To divide long rather than int values, use the similar
function ldiv.
Portability
div is ANSI.
No supporting OS subroutines are required.
Next: gcvt, gcvtf—format double or float as string, Previous: div—divide two integers, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
ecvt, ecvtf, fcvt, fcvtf—double or float to stringSynopsis
#include <stdlib.h>
char *ecvt(double val, int chars, int *decpt, int *sgn);
char *ecvtf(float val, int chars, int *decpt, int *sgn);
char *fcvt(double val, int decimals,
int *decpt, int *sgn);
char *fcvtf(float val, int decimals,
int *decpt, int *sgn);
Description
ecvt and fcvt produce (null-terminated) strings of digits
representating the double number val.
ecvtf and fcvtf produce the corresponding character
representations of float numbers.
(The stdlib functions ecvtbuf and fcvtbuf are reentrant
versions of ecvt and fcvt.)
The only difference between ecvt and fcvt is the
interpretation of the second argument (chars or decimals).
For ecvt, the second argument chars specifies the total number
of characters to write (which is also the number of significant digits
in the formatted string, since these two functions write only digits).
For fcvt, the second argument decimals specifies the number of
characters to write after the decimal point; all digits for the integer
part of val are always included.
Since ecvt and fcvt write only digits in the output string,
they record the location of the decimal point in *decpt, and
the sign of the number in *sgn. After formatting a number,
*decpt contains the number of digits to the left of the
decimal point. *sgn contains 0 if the number is positive,
and 1 if it is negative.
Returns
All four functions return a pointer to the new string containing a
character representation of val.
Portability
None of these functions are ANSI C.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: ecvtbuf, fcvtbuf—double or float to string, Previous: ecvt, ecvtf, fcvt, fcvtf—double or float to string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
gcvt, gcvtf—format double or float as stringSynopsis
#include <stdlib.h> char *gcvt(double val, int precision, char *buf); char *gcvtf(float val, int precision, char *buf);
Description
gcvt writes a fully formatted number as a null-terminated
string in the buffer *buf. gcvtf produces corresponding
character representations of float numbers.
gcvt uses the same rules as the printf format
‘%.precisiong’—only negative values are signed (with
‘-’), and either exponential or ordinary decimal-fraction format
is chosen depending on the number of significant digits (specified by
precision).
Returns
The result is a pointer to the formatted representation of val
(the same as the argument buf).
Portability
Neither function is ANSI C.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: __env_lock, __env_unlock—lock environ variable, Previous: gcvt, gcvtf—format double or float as string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
ecvtbuf, fcvtbuf—double or float to stringSynopsis
#include <stdio.h>
char *ecvtbuf(double val, int chars, int *decpt,
int *sgn, char *buf);
char *fcvtbuf(double val, int decimals, int *decpt,
int *sgn, char *buf);
Description
ecvtbuf and fcvtbuf produce (null-terminated) strings
of digits representating the double number val.
The only difference between ecvtbuf and fcvtbuf is the
interpretation of the second argument (chars or
decimals). For ecvtbuf, the second argument chars
specifies the total number of characters to write (which is
also the number of significant digits in the formatted string,
since these two functions write only digits). For fcvtbuf,
the second argument decimals specifies the number of
characters to write after the decimal point; all digits for
the integer part of val are always included.
Since ecvtbuf and fcvtbuf write only digits in the
output string, they record the location of the decimal point
in *decpt, and the sign of the number in *sgn.
After formatting a number, *decpt contains the number
of digits to the left of the decimal point. *sgn
contains 0 if the number is positive, and 1 if it is
negative. For both functions, you supply a pointer buf to
an area of memory to hold the converted string.
Returns
Both functions return a pointer to buf, the string
containing a character representation of val.
Portability
Neither function is ANSI C.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: exit—end program execution, Previous: ecvtbuf, fcvtbuf—double or float to string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
__env_lock, __env_unlock—lock environ variableSynopsis
#include <envlock.h> void __env_lock (struct _reent *reent); void __env_unlock (struct _reent *reent);
Description
The setenv family of routines call these functions when they need to
modify the environ variable. The version of these routines supplied in the
library use the lock API defined in sys/lock.h. If multiple threads of
execution can call setenv, or if setenv can be called reentrantly,
then you need to define your own versions of these functions in order to
safely lock the memory pool during a call. If you do not, the memory pool
may become corrupted.
A call to setenv may call __env_lock recursively; that is,
the sequence of calls may go __env_lock, __env_lock,
__env_unlock, __env_unlock. Any implementation of these
routines must be careful to avoid causing a thread to wait for a lock
that it already holds.
Next: getenv—look up environment variable, Previous: __env_lock, __env_unlock—lock environ variable, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
exit—end program executionSynopsis
#include <stdlib.h> void exit(int code);
Description
Use exit to return control from a program to the host operating
environment. Use the argument code to pass an exit status to the
operating environment: two particular values, EXIT_SUCCESS and
EXIT_FAILURE, are defined in ‘stdlib.h’ to indicate success or
failure in a portable fashion.
exit does two kinds of cleanup before ending execution of your
program. First, it calls all application-defined cleanup functions
you have enrolled with atexit. Second, files and streams are
cleaned up: any pending output is delivered to the host system, each
open file or stream is closed, and files created by tmpfile are
deleted.
Returns
exit does not return to its caller.
Portability
ANSI C requires exit, and specifies that EXIT_SUCCESS and
EXIT_FAILURE must be defined.
Supporting OS subroutines required: _exit.
Next: itoa—integer to string, Previous: exit—end program execution, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
getenv—look up environment variableSynopsis
#include <stdlib.h> char *getenv(const char *name);
Description
getenv searches the list of environment variable names and values
(using the global pointer “char **environ”) for a variable whose
name matches the string at name. If a variable name matches,
getenv returns a pointer to the associated value.
Returns
A pointer to the (string) value of the environment variable, or
NULL if there is no such environment variable.
Portability
getenv is ANSI, but the rules for properly forming names of environment
variables vary from one system to another.
getenv requires a global pointer environ.
Next: labs—long integer absolute value, Previous: getenv—look up environment variable, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
itoa—integer to stringSynopsis
#include <stdlib.h> char *itoa(int value, char *str, int base); char *__itoa(int value, char *str, int base);
Description
itoa converts the integer value to a null-terminated string
using the specified base, which must be between 2 and 36, inclusive.
If base is 10, value is treated as signed and the string will be
prefixed with ’-’ if negative. For all other bases, value is treated as
unsigned. str should be an array long enough to contain the converted
value, which in the worst case is sizeof(int)*8+1 bytes.
Returns
A pointer to the string, str, or NULL if base is invalid.
Portability
itoa is non-ANSI.
No supporting OS subroutine calls are required.
Next: ldiv—divide two long integers, Previous: itoa—integer to string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
labs—long integer absolute valueSynopsis
#include <stdlib.h> long labs(long i);
Description
labs returns
the absolute value of i (also called the magnitude
of i). That is, if i is negative, the result is the opposite
of i, but if i is nonnegative the result is i.
The similar function abs uses and returns int rather than
long values.
Returns
The result is a nonnegative long integer.
Portability
labs is ANSI.
No supporting OS subroutine calls are required.
Next: llabs—compute the absolute value of an long long integer., Previous: labs—long integer absolute value, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
ldiv—divide two long integersSynopsis
#include <stdlib.h> ldiv_t ldiv(long n, long d);
Description
Divide
n/d,
returning quotient and remainder as two long integers in a structure ldiv_t.
Returns
The result is represented with the structure
typedef struct
{
long quot;
long rem;
} ldiv_t;
where the quot field represents the quotient, and rem the
remainder. For nonzero d, if ‘r = ldiv(n,d);’ then
n equals ‘r.rem + d*r.quot’.
To divide int rather than long values, use the similar
function div.
Portability
ldiv is ANSI.
No supporting OS subroutines are required.
Next: lldiv—divide two long long integers, Previous: ldiv—divide two long integers, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
llabs—compute the absolute value of an long long integer.Synopsis
#include <stdlib.h> long long llabs(long long j);
Description
The llabs function computes the absolute value of the long long integer
argument j (also called the magnitude of j).
The similar function labs uses and returns long rather than
long long values.
Returns
A nonnegative long long integer.
Portability
llabs is ISO 9899 (C99) compatable.
No supporting OS subroutines are required.
Next: malloc, realloc, free—manage memory, Previous: llabs—compute the absolute value of an long long integer., Up: Standard Utility Functions (stdlib.h) [Contents][Index]
lldiv—divide two long long integersSynopsis
#include <stdlib.h> lldiv_t lldiv(long long n, long long d);
Description
Divide
n/d,
returning quotient and remainder as two long long integers in a structure
lldiv_t.
Returns
The result is represented with the structure
typedef struct
{
long long quot;
long long rem;
} lldiv_t;
where the quot field represents the quotient, and rem the
remainder. For nonzero d, if ‘r = ldiv(n,d);’ then
n equals ‘r.rem + d*r.quot’.
To divide long rather than long long values, use the similar
function ldiv.
Portability
lldiv is ISO 9899 (C99) compatable.
No supporting OS subroutines are required.
Next: mallinfo, malloc_stats, mallopt—malloc support, Previous: lldiv—divide two long long integers, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
malloc, realloc, free—manage memorySynopsis
#include <stdlib.h>
void *malloc(size_t nbytes);
void *realloc(void *aptr, size_t nbytes);
void *reallocf(void *aptr, size_t nbytes);
void free(void *aptr);
void *memalign(size_t align, size_t nbytes);
size_t malloc_usable_size(void *aptr);
void *_malloc_r(void *reent, size_t nbytes);
void *_realloc_r(void *reent,
void *aptr, size_t nbytes);
void *_reallocf_r(void *reent,
void *aptr, size_t nbytes);
void _free_r(void *reent, void *aptr);
void *_memalign_r(void *reent,
size_t align, size_t nbytes);
size_t _malloc_usable_size_r(void *reent, void *aptr);
Description
These functions manage a pool of system memory.
Use malloc to request allocation of an object with at least
nbytes bytes of storage available. If the space is available,
malloc returns a pointer to a newly allocated block as its result.
If you already have a block of storage allocated by malloc, but
you no longer need all the space allocated to it, you can make it
smaller by calling realloc with both the object pointer and the
new desired size as arguments. realloc guarantees that the
contents of the smaller object match the beginning of the original object.
Similarly, if you need more space for an object, use realloc to
request the larger size; again, realloc guarantees that the
beginning of the new, larger object matches the contents of the
original object.
When you no longer need an object originally allocated by malloc
or realloc (or the related function calloc), return it to the
memory storage pool by calling free with the address of the object
as the argument. You can also use realloc for this purpose by
calling it with 0 as the nbytes argument.
The reallocf function behaves just like realloc except if the
function is required to allocate new storage and this fails. In this
case reallocf will free the original object passed in whereas
realloc will not.
The memalign function returns a block of size nbytes aligned
to a align boundary. The align argument must be a power of
two.
The malloc_usable_size function takes a pointer to a block
allocated by malloc. It returns the amount of space that is
available in the block. This may or may not be more than the size
requested from malloc, due to alignment or minimum size
constraints.
The alternate functions _malloc_r, _realloc_r, _reallocf_r,
_free_r, _memalign_r, and _malloc_usable_size_r are reentrant
versions. The extra argument reent is a pointer to a reentrancy structure.
If you have multiple threads of execution which may call any of these
routines, or if any of these routines may be called reentrantly, then
you must provide implementations of the __malloc_lock and
__malloc_unlock functions for your system. See the documentation
for those functions.
These functions operate by calling the function _sbrk_r or
sbrk, which allocates space. You may need to provide one of these
functions for your system. _sbrk_r is called with a positive
value to allocate more space, and with a negative value to release
previously allocated space if it is no longer required.
See Definitions for OS interface.
Returns
malloc returns a pointer to the newly allocated space, if
successful; otherwise it returns NULL. If your application needs
to generate empty objects, you may use malloc(0) for this purpose.
realloc returns a pointer to the new block of memory, or NULL
if a new block could not be allocated. NULL is also the result
when you use ‘realloc(aptr,0)’ (which has the same effect as
‘free(aptr)’). You should always check the result of
realloc; successful reallocation is not guaranteed even when
you request a smaller object.
free does not return a result.
memalign returns a pointer to the newly allocated space.
malloc_usable_size returns the usable size.
Portability
malloc, realloc, and free are specified by the ANSI C
standard, but other conforming implementations of malloc may
behave differently when nbytes is zero.
memalign is part of SVR4.
malloc_usable_size is not portable.
Supporting OS subroutines required: sbrk.
Next: __malloc_lock, __malloc_unlock—lock malloc pool, Previous: malloc, realloc, free—manage memory, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
mallinfo, malloc_stats, mallopt—malloc supportSynopsis
#include <malloc.h> struct mallinfo mallinfo(void); void malloc_stats(void); int mallopt(int parameter, value); struct mallinfo _mallinfo_r(void *reent); void _malloc_stats_r(void *reent); int _mallopt_r(void *reent, int parameter, value);
Description
mallinfo returns a structure describing the current state of
memory allocation. The structure is defined in malloc.h. The
following fields are defined: arena is the total amount of space
in the heap; ordblks is the number of chunks which are not in use;
uordblks is the total amount of space allocated by malloc;
fordblks is the total amount of space not in use; keepcost is
the size of the top most memory block.
malloc_stats print some statistics about memory allocation on
standard error.
mallopt takes a parameter and a value. The parameters are defined
in malloc.h, and may be one of the following: M_TRIM_THRESHOLD
sets the maximum amount of unused space in the top most block before
releasing it back to the system in free (the space is released by
calling _sbrk_r with a negative argument); M_TOP_PAD is the
amount of padding to allocate whenever _sbrk_r is called to
allocate more space.
The alternate functions _mallinfo_r, _malloc_stats_r, and
_mallopt_r are reentrant versions. The extra argument reent
is a pointer to a reentrancy structure.
Returns
mallinfo returns a mallinfo structure. The structure is defined
in malloc.h.
malloc_stats does not return a result.
mallopt returns zero if the parameter could not be set, or
non-zero if it could be set.
Portability
mallinfo and mallopt are provided by SVR4, but mallopt
takes different parameters on different systems. malloc_stats is
not portable.
Next: mblen—minimal multibyte length function, Previous: mallinfo, malloc_stats, mallopt—malloc support, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
__malloc_lock, __malloc_unlock—lock malloc poolSynopsis
#include <malloc.h> void __malloc_lock (struct _reent *reent); void __malloc_unlock (struct _reent *reent);
Description
The malloc family of routines call these functions when they need to lock
the memory pool. The version of these routines supplied in the library use
the lock API defined in sys/lock.h. If multiple threads of execution can
call malloc, or if malloc can be called reentrantly, then you need to
define your own versions of these functions in order to safely lock the
memory pool during a call. If you do not, the memory pool may become
corrupted.
A call to malloc may call __malloc_lock recursively; that is,
the sequence of calls may go __malloc_lock, __malloc_lock,
__malloc_unlock, __malloc_unlock. Any implementation of these
routines must be careful to avoid causing a thread to wait for a lock
that it already holds.
Next: mbsrtowcs, mbsnrtowcs—convert a character string to a wide-character string, Previous: __malloc_lock, __malloc_unlock—lock malloc pool, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
mblen—minimal multibyte length functionSynopsis
#include <stdlib.h> int mblen(const char *s, size_t n);
Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of mblen. In this case, the
only “multi-byte character sequences” recognized are single bytes,
and thus 1 is returned unless s is the null pointer or
has a length of 0 or is the empty string.
When _MB_CAPABLE is defined, this routine calls _mbtowc_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Returns
This implementation of mblen returns 0 if
s is NULL or the empty string; it returns 1 if not _MB_CAPABLE or
the character is a single-byte character; it returns -1
if the multi-byte character is invalid; otherwise it returns
the number of bytes in the multibyte character.
Portability
mblen is required in the ANSI C standard. However, the precise
effects vary with the locale.
mblen requires no supporting OS subroutines.
Next: mbstowcs—minimal multibyte string to wide char converter, Previous: mblen—minimal multibyte length function, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
mbsrtowcs, mbsnrtowcs—convert a character string to a wide-character stringSynopsis
#include <wchar.h>
size_t mbsrtowcs(wchar_t *__restrict dst,
const char **__restrict src,
size_t len,
mbstate_t *__restrict ps);
#include <wchar.h>
size_t _mbsrtowcs_r(struct _reent *ptr, wchar_t *dst,
const char **src, size_t len,
mbstate_t *ps);
#include <wchar.h>
size_t mbsnrtowcs(wchar_t *__ restrict dst,
const char **__restrict src, size_t nms,
size_t len, mbstate_t *__restrict ps);
#include <wchar.h>
size_t _mbsnrtowcs_r(struct _reent *ptr, wchar_t *dst,
const char **src, size_t nms,
size_t len, mbstate_t *ps);
Description
The mbsrtowcs function converts a sequence of multibyte characters
pointed to indirectly by src into a sequence of corresponding wide
characters and stores at most len of them in the wchar_t array pointed
to by dst, until it encounters a terminating null character (’\0’).
If dst is NULL, no characters are stored.
If dst is not NULL, the pointer pointed to by src is updated to point to the character after the one that conversion stopped at. If conversion stops because a null character is encountered, *src is set to NULL.
The mbstate_t argument, ps, is used to keep track of the shift state. If
it is NULL, mbsrtowcs uses an internal, static mbstate_t object, which
is initialized to the initial conversion state at program startup.
The mbsnrtowcs function behaves identically to mbsrtowcs, except that
conversion stops after reading at most nms bytes from the buffer pointed
to by src.
Returns
The mbsrtowcs and mbsnrtowcs functions return the number of wide
characters stored in the array pointed to by dst if successful, otherwise
it returns (size_t)-1.
Portability
mbsrtowcs is defined by the C99 standard.
mbsnrtowcs is defined by the POSIX.1-2008 standard.
Next: mbtowc—minimal multibyte to wide char converter, Previous: mbsrtowcs, mbsnrtowcs—convert a character string to a wide-character string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
mbstowcs—minimal multibyte string to wide char converterSynopsis
#include <stdlib.h> int mbstowcs(wchar_t *restrict pwc, const char *restrict s, size_t n);
Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of mbstowcs. In this case, the
only “multi-byte character sequences” recognized are single bytes,
and they are “converted” to wide-char versions simply by byte
extension.
When _MB_CAPABLE is defined, this routine calls _mbstowcs_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Returns
This implementation of mbstowcs returns 0 if
s is NULL or is the empty string;
it returns -1 if _MB_CAPABLE and one of the
multi-byte characters is invalid or incomplete;
otherwise it returns the minimum of: n or the
number of multi-byte characters in s plus 1 (to
compensate for the nul character).
If the return value is -1, the state of the pwc string is
indeterminate. If the input has a length of 0, the output
string will be modified to contain a wchar_t nul terminator.
Portability
mbstowcs is required in the ANSI C standard. However, the precise
effects vary with the locale.
mbstowcs requires no supporting OS subroutines.
Next: on_exit—request execution of function with argument at program exit, Previous: mbstowcs—minimal multibyte string to wide char converter, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
mbtowc—minimal multibyte to wide char converterSynopsis
#include <stdlib.h> int mbtowc(wchar_t *restrict pwc, const char *restrict s, size_t n);
Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of mbtowc. In this case,
only “multi-byte character sequences” recognized are single bytes,
and they are “converted” to themselves.
Each call to mbtowc copies one character from *s to
*pwc, unless s is a null pointer. The argument n
is ignored.
When _MB_CAPABLE is defined, this routine calls _mbtowc_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Returns
This implementation of mbtowc returns 0 if
s is NULL or is the empty string;
it returns 1 if not _MB_CAPABLE or
the character is a single-byte character; it returns -1
if n is 0 or the multi-byte character is invalid;
otherwise it returns the number of bytes in the multibyte character.
If the return value is -1, no changes are made to the pwc
output string. If the input is the empty string, a wchar_t nul
is placed in the output string and 0 is returned. If the input
has a length of 0, no changes are made to the pwc output string.
Portability
mbtowc is required in the ANSI C standard. However, the precise
effects vary with the locale.
mbtowc requires no supporting OS subroutines.
Next: qsort—sort an array, Previous: mbtowc—minimal multibyte to wide char converter, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
on_exit—request execution of function with argument at program exitSynopsis
#include <stdlib.h> int on_exit (void (*function)(int, void *), void *arg);
Description
You can use on_exit to enroll functions in a list of functions that
will be called when your program terminates normally. The argument is
a pointer to a user-defined function which takes two arguments. The
first is the status code passed to exit and the second argument is of type
pointer to void. The function must not return a result. The value
of arg is registered and passed as the argument to function.
The functions are kept in a LIFO stack; that is, the last function
enrolled by atexit or on_exit will be the first to execute when
your program exits. You can intermix functions using atexit and
on_exit.
There is no built-in limit to the number of functions you can enroll
in this list; however, after every group of 32 functions is enrolled,
atexit/on_exit will call malloc to get space for the next part
of the list. The initial list of 32 functions is statically allocated, so
you can always count on at least that many slots available.
Returns
on_exit returns 0 if it succeeds in enrolling your function,
-1 if it fails (possible only if no space was available for
malloc to extend the list of functions).
Portability
on_exit is a non-standard glibc extension
Supporting OS subroutines required: None
Next: rand, srand—pseudo-random numbers, Previous: on_exit—request execution of function with argument at program exit, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
qsort—sort an arraySynopsis
#include <stdlib.h>
void qsort(void *base, size_t nmemb, size_t size,
int (*compar)(const void *, const void *) );
Description
qsort sorts an array (beginning at base) of nmemb objects.
size describes the size of each element of the array.
You must supply a pointer to a comparison function, using the argument
shown as compar. (This permits sorting objects of unknown
properties.) Define the comparison function to accept two arguments,
each a pointer to an element of the array starting at base. The
result of (*compar) must be negative if the first argument is
less than the second, zero if the two arguments match, and positive if
the first argument is greater than the second (where “less than” and
“greater than” refer to whatever arbitrary ordering is appropriate).
The array is sorted in place; that is, when qsort returns, the
array elements beginning at base have been reordered.
Returns
qsort does not return a result.
Portability
qsort is required by ANSI (without specifying the sorting algorithm).
Next: random, srandom—pseudo-random numbers, Previous: qsort—sort an array, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
rand, srand—pseudo-random numbersSynopsis
#include <stdlib.h> int rand(void); void srand(unsigned int seed); int rand_r(unsigned int *seed);
Description
rand returns a different integer each time it is called; each
integer is chosen by an algorithm designed to be unpredictable, so
that you can use rand when you require a random number.
The algorithm depends on a static variable called the “random seed”;
starting with a given value of the random seed always produces the
same sequence of numbers in successive calls to rand.
You can set the random seed using srand; it does nothing beyond
storing its argument in the static variable used by rand. You can
exploit this to make the pseudo-random sequence less predictable, if
you wish, by using some other unpredictable value (often the least
significant parts of a time-varying value) as the random seed before
beginning a sequence of calls to rand; or, if you wish to ensure
(for example, while debugging) that successive runs of your program
use the same “random” numbers, you can use srand to set the same
random seed at the outset.
Returns
rand returns the next pseudo-random integer in sequence; it is a
number between 0 and RAND_MAX (inclusive).
srand does not return a result.
Notes
rand and srand are unsafe for multi-threaded applications.
rand_r is thread-safe and should be used instead.
Portability
rand is required by ANSI, but the algorithm for pseudo-random
number generation is not specified; therefore, even if you use
the same random seed, you cannot expect the same sequence of results
on two different systems.
rand requires no supporting OS subroutines.
Next: rand48, drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48, lcong48—pseudo-random number generators and initialization routines, Previous: rand, srand—pseudo-random numbers, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
random, srandom—pseudo-random numbersSynopsis
#define _XOPEN_SOURCE 500 #include <stdlib.h> long int random(void); void srandom(unsigned int seed);
Description
random returns a different integer each time it is called; each
integer is chosen by an algorithm designed to be unpredictable, so
that you can use random when you require a random number.
The algorithm depends on a static variable called the “random seed”;
starting with a given value of the random seed always produces the
same sequence of numbers in successive calls to random.
You can set the random seed using srandom; it does nothing beyond
storing its argument in the static variable used by rand. You can
exploit this to make the pseudo-random sequence less predictable, if
you wish, by using some other unpredictable value (often the least
significant parts of a time-varying value) as the random seed before
beginning a sequence of calls to rand; or, if you wish to ensure
(for example, while debugging) that successive runs of your program
use the same “random” numbers, you can use srandom to set the same
random seed at the outset.
Returns
random returns the next pseudo-random integer in sequence; it is a
number between 0 and RAND_MAX (inclusive).
srandom does not return a result.
Notes
random and srandom are unsafe for multi-threaded applications.
_XOPEN_SOURCE may be any value >= 500.
Portability
random is required by XSI. This implementation uses the same
algorithm as rand.
random requires no supporting OS subroutines.
Next: rpmatch—determine whether response to question is affirmative or negative, Previous: random, srandom—pseudo-random numbers, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
rand48, drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48, lcong48—pseudo-random number generators and initialization routinesSynopsis
#include <stdlib.h> double drand48(void); double erand48(unsigned short xseed[3]); long lrand48(void); long nrand48(unsigned short xseed[3]); long mrand48(void); long jrand48(unsigned short xseed[3]); void srand48(long seed); unsigned short *seed48(unsigned short xseed[3]); void lcong48(unsigned short p[7]);
Description
The rand48 family of functions generates pseudo-random numbers
using a linear congruential algorithm working on integers 48 bits in size.
The particular formula employed is
r(n+1) = (a * r(n) + c) mod m
where the default values are
for the multiplicand a = 0xfdeece66d = 25214903917 and
the addend c = 0xb = 11. The modulo is always fixed at m = 2 ** 48.
r(n) is called the seed of the random number generator.
For all the six generator routines described next, the first computational step is to perform a single iteration of the algorithm.
drand48 and erand48
return values of type double. The full 48 bits of r(n+1) are
loaded into the mantissa of the returned value, with the exponent set
such that the values produced lie in the interval [0.0, 1.0].
lrand48 and nrand48
return values of type long in the range
[0, 2**31-1]. The high-order (31) bits of
r(n+1) are loaded into the lower bits of the returned value, with
the topmost (sign) bit set to zero.
mrand48 and jrand48
return values of type long in the range
[-2**31, 2**31-1]. The high-order (32) bits of
r(n+1) are loaded into the returned value.
drand48, lrand48, and mrand48
use an internal buffer to store r(n). For these functions
the initial value of r(0) = 0x1234abcd330e = 20017429951246.
On the other hand, erand48, nrand48, and jrand48
use a user-supplied buffer to store the seed r(n),
which consists of an array of 3 shorts, where the zeroth member
holds the least significant bits.
All functions share the same multiplicand and addend.
srand48 is used to initialize the internal buffer r(n) of
drand48, lrand48, and mrand48
such that the 32 bits of the seed value are copied into the upper 32 bits
of r(n), with the lower 16 bits of r(n) arbitrarily being set to 0x330e.
Additionally, the constant multiplicand and addend of the algorithm are
reset to the default values given above.
seed48 also initializes the internal buffer r(n) of
drand48, lrand48, and mrand48,
but here all 48 bits of the seed can be specified in an array of 3 shorts,
where the zeroth member specifies the lowest bits. Again,
the constant multiplicand and addend of the algorithm are
reset to the default values given above.
seed48 returns a pointer to an array of 3 shorts which contains
the old seed.
This array is statically allocated, thus its contents are lost after
each new call to seed48.
Finally, lcong48 allows full control over the multiplicand and
addend used in drand48, erand48, lrand48, nrand48,
mrand48, and jrand48,
and the seed used in drand48, lrand48, and mrand48.
An array of 7 shorts is passed as parameter; the first three shorts are
used to initialize the seed; the second three are used to initialize the
multiplicand; and the last short is used to initialize the addend.
It is thus not possible to use values greater than 0xffff as the addend.
Note that all three methods of seeding the random number generator always also set the multiplicand and addend for any of the six generator calls.
For a more powerful random number generator, see random.
Portability
SUS requires these functions.
No supporting OS subroutines are required.
Next: strtod, strtof, strtold, strtod_l, strtof_l, strtold_l—string to double or float, Previous: rand48, drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48, lcong48—pseudo-random number generators and initialization routines, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
rpmatch—determine whether response to question is affirmative or negativeSynopsis
#include <stdlib.h> int rpmatch(const char *response);
Description
The rpmatch function determines whether response is an affirmative
or negative response to a question according to the current locale.
Returns
rpmatch returns 1 if response is affirmative, 0 if negative, or -1
if not recognized as either.
Portability
rpmatch is a BSD extension also found in glibc.
Notes
No supporting OS subroutines are required.
Next: strtol, strtol_l—string to long, Previous: rpmatch—determine whether response to question is affirmative or negative, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
strtod, strtof, strtold, strtod_l, strtof_l, strtold_l—string to double or floatSynopsis
#include <stdlib.h>
double strtod(const char *restrict str, char **restrict tail);
float strtof(const char *restrict str, char **restrict tail);
long double strtold(const char *restrict str,
char **restrict tail);
#include <stdlib.h>
double strtod_l(const char *restrict str, char **restrict tail,
locale_t locale);
float strtof_l(const char *restrict str, char **restrict tail,
locale_t locale);
long double strtold_l(const char *restrict str,
char **restrict tail,
locale_t locale);
double _strtod_r(void *reent,
const char *restrict str, char **restrict tail);
Description
strtod, strtof, strtold parse the character string
str, producing a substring which can be converted to a double,
float, or long double value, respectively. The substring converted
is the longest initial subsequence of str, beginning with the
first non-whitespace character, that has one of these formats:
[+|-]digits[.[digits]][(e|E)[+|-]digits] [+|-].digits[(e|E)[+|-]digits] [+|-](i|I)(n|N)(f|F)[(i|I)(n|N)(i|I)(t|T)(y|Y)] [+|-](n|N)(a|A)(n|N)[<(>[hexdigits]<)>] [+|-]0(x|X)hexdigits[.[hexdigits]][(p|P)[+|-]digits] [+|-]0(x|X).hexdigits[(p|P)[+|-]digits]
The substring contains no characters if str is empty, consists
entirely of whitespace, or if the first non-whitespace
character is something other than +, -, ., or a
digit, and cannot be parsed as infinity or NaN. If the platform
does not support NaN, then NaN is treated as an empty substring.
If the substring is empty, no conversion is done, and
the value of str is stored in *tail. Otherwise,
the substring is converted, and a pointer to the final string
(which will contain at least the terminating null character of
str) is stored in *tail. If you want no
assignment to *tail, pass a null pointer as tail.
This implementation returns the nearest machine number to the
input decimal string. Ties are broken by using the IEEE
round-even rule. However, strtof is currently subject to
double rounding errors.
strtod_l, strtof_l, strtold_l are like strtod,
strtof, strtold but perform the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is
undefined.
The alternate function _strtod_r is a reentrant version.
The extra argument reent is a pointer to a reentrancy structure.
Returns
These functions return the converted substring value, if any. If
no conversion could be performed, 0 is returned. If the correct
value is out of the range of representable values, plus or minus
HUGE_VAL (HUGE_VALF, HUGE_VALL) is returned, and
ERANGE is stored in errno. If the correct value would cause
underflow, 0 is returned and ERANGE is stored in errno.
Portability
strtod is ANSI.
strtof, strtold are C99.
strtod_l, strtof_l, strtold_l are GNU extensions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: strtoll, strtoll_l—string to long long, Previous: strtod, strtof, strtold, strtod_l, strtof_l, strtold_l—string to double or float, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
strtol, strtol_l—string to longSynopsis
#include <stdlib.h>
long strtol(const char *restrict s, char **restrict ptr,
int base);
#include <stdlib.h>
long strtol_l(const char *restrict s, char **restrict ptr,
int base, locale_t locale);
long _strtol_r(void *reent, const char *restrict s,
char **restrict ptr,int base);
Description
The function strtol converts the string *s to
a long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of characters resembling an integer in the radix specified by base;
and a trailing portion consisting of zero or more unparseable characters,
and always including the terminating null character. Then, it attempts
to convert the subject string into a long and returns the
result.
If the value of base is 0, the subject string is expected to look
like a normal C integer constant: an optional sign, a possible ‘0x’
indicating a hexadecimal base, and a number. If base is between
2 and 36, the expected form of the subject is a sequence of letters
and digits representing an integer in the radix specified by base,
with an optional plus or minus sign. The letters a–z (or,
equivalently, A–Z) are used to signify values from 10 to 35;
only letters whose ascribed values are less than base are
permitted. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible letter or digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
strtol attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. If the subject string begins with
a minus sign, the value is negated. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (or not in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
strtol_l is like strtol but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
The alternate function _strtol_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
strtol, strtol_l return the converted value, if any. If no
conversion was made, 0 is returned.
strtol, strtol_l return LONG_MAX or LONG_MIN if the
magnitude of the converted value is too large, and sets errno
to ERANGE.
Portability
strtol is ANSI.
strtol_l is a GNU extension.
No supporting OS subroutines are required.
Next: strtoul, strtoul_l—string to unsigned long, Previous: strtol, strtol_l—string to long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
strtoll, strtoll_l—string to long longSynopsis
#include <stdlib.h>
long long strtoll(const char *restrict s, char **restrict ptr,
int base);
#include <stdlib.h>
long long strtoll_l(const char *restrict s,
char **restrict ptr, int base,
locale_t locale);
long long _strtoll_r(void *reent,
const char *restrict s,
char **restrict ptr, int base);
Description
The function strtoll converts the string *s to
a long long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of characters resembling an integer in the radix specified by base;
and a trailing portion consisting of zero or more unparseable characters,
and always including the terminating null character. Then, it attempts
to convert the subject string into a long long and returns the
result.
If the value of base is 0, the subject string is expected to look
like a normal C integer constant: an optional sign, a possible ‘0x’
indicating a hexadecimal base, and a number. If base is between
2 and 36, the expected form of the subject is a sequence of letters
and digits representing an integer in the radix specified by base,
with an optional plus or minus sign. The letters a–z (or,
equivalently, A–Z) are used to signify values from 10 to 35;
only letters whose ascribed values are less than base are
permitted. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible letter or digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
strtoll attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. If the subject string begins with
a minus sign, the value is negated. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (or not in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
strtoll_l is like strtoll but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
The alternate function _strtoll_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
strtoll, strtoll_l return the converted value, if any. If no
conversion was made, 0 is returned.
strtoll, strtoll_l return LONG_LONG_MAX or LONG_LONG_MIN
if the magnitude of the converted value is too large, and sets errno
to ERANGE.
Portability
strtoll is ANSI.
strtoll_l is a GNU extension.
No supporting OS subroutines are required.
Next: strtoull, strtoull_l—string to unsigned long long, Previous: strtoll, strtoll_l—string to long long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
strtoul, strtoul_l—string to unsigned longSynopsis
#include <stdlib.h>
unsigned long strtoul(const char *restrict s,
char **restrict ptr, int base);
#include <stdlib.h>
unsigned long strtoul_l(const char *restrict s,
char **restrict ptr, int base,
locale_t locale);
unsigned long _strtoul_r(void *reent, const char *restrict s,
char **restrict ptr, int base);
Description
The function strtoul converts the string *s to
an unsigned long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of the digits meaningful in the radix specified by base
(for example, 0 through 7 if the value of base is 8);
and a trailing portion consisting of one or more unparseable characters,
which always includes the terminating null character. Then, it attempts
to convert the subject string into an unsigned long integer, and returns the
result.
If the value of base is zero, the subject string is expected to look
like a normal C integer constant (save that no optional sign is permitted):
a possible 0x indicating hexadecimal radix, and a number.
If base is between 2 and 36, the expected form of the subject is a
sequence of digits (which may include letters, depending on the
base) representing an integer in the radix specified by base.
The letters a–z (or A–Z) are used as digits valued from
10 to 35. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
strtoul attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (that is, if *s does not start
with a substring in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
strtoul_l is like strtoul but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
The alternate function _strtoul_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
strtoul, strtoul_l return the converted value, if any. If no
conversion was made, 0 is returned.
strtoul, strtoul_l return ULONG_MAX if the magnitude of the
converted value is too large, and sets errno to ERANGE.
Portability
strtoul is ANSI.
strtoul_l is a GNU extension.
strtoul requires no supporting OS subroutines.
Next: wcsrtombs, wcsnrtombs—convert a wide-character string to a character string, Previous: strtoul, strtoul_l—string to unsigned long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
strtoull, strtoull_l—string to unsigned long longSynopsis
#include <stdlib.h>
unsigned long long strtoull(const char *restrict s,
char **restrict ptr, int base);
#include <stdlib.h>
unsigned long long strtoull_l(const char *restrict s,
char **restrict ptr, int base,
locale_t locale);
unsigned long long _strtoull_r(void *reent,
const char *restrict s,
char **restrict ptr, int base);
Description
The function strtoull converts the string *s to
an unsigned long long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of the digits meaningful in the radix specified by base
(for example, 0 through 7 if the value of base is 8);
and a trailing portion consisting of one or more unparseable characters,
which always includes the terminating null character. Then, it attempts
to convert the subject string into an unsigned long long integer, and returns the
result.
If the value of base is zero, the subject string is expected to look
like a normal C integer constant (save that no optional sign is permitted):
a possible 0x indicating hexadecimal radix, and a number.
If base is between 2 and 36, the expected form of the subject is a
sequence of digits (which may include letters, depending on the
base) representing an integer in the radix specified by base.
The letters a–z (or A–Z) are used as digits valued from
10 to 35. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
strtoull attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (that is, if *s does not start
with a substring in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
strtoull_l is like strtoull but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
The alternate function _strtoull_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
strtoull, strtoull_l return the converted value, if any. If no
conversion was made, 0 is returned.
strtoull, strtoull_l return ULONG_LONG_MAX if the magnitude
of the converted value is too large, and sets errno to ERANGE.
Portability
strtoull is ANSI.
strtoull_l is a GNU extension.
strtoull requires no supporting OS subroutines.
Next: wcstod, wcstof, wcstold, wcstod_l, wcstof_l, wcstold_l—wide char string to double or float, Previous: strtoull, strtoull_l—string to unsigned long long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcsrtombs, wcsnrtombs—convert a wide-character string to a character stringSynopsis
#include <wchar.h>
size_t wcsrtombs(char *__restrict dst,
const wchar_t **__restrict src, size_t len,
mbstate_t *__restrict ps);
#include <wchar.h>
size_t _wcsrtombs_r(struct _reent *ptr, char *dst,
const wchar_t **src, size_t len,
mbstate_t *ps);
#include <wchar.h>
size_t wcsnrtombs(char *__restrict dst,
const wchar_t **__restrict src,
size_t nwc, size_t len,
mbstate_t *__restrict ps);
#include <wchar.h>
size_t _wcsnrtombs_r(struct _reent *ptr, char *dst,
const wchar_t **src, size_t nwc,
size_t len, mbstate_t *ps);
Description
The wcsrtombs function converts a string of wide characters indirectly
pointed to by src to a corresponding multibyte character string stored in
the array pointed to by dst. No more than len bytes are written to
dst.
If dst is NULL, no characters are stored.
If dst is not NULL, the pointer pointed to by src is updated to point to the character after the one that conversion stopped at. If conversion stops because a null character is encountered, *src is set to NULL.
The mbstate_t argument, ps, is used to keep track of the shift state. If
it is NULL, wcsrtombs uses an internal, static mbstate_t object, which
is initialized to the initial conversion state at program startup.
The wcsnrtombs function behaves identically to wcsrtombs, except that
conversion stops after reading at most nwc characters from the buffer
pointed to by src.
Returns
The wcsrtombs and wcsnrtombs functions return the number of bytes
stored in the array pointed to by dst (not including any terminating
null), if successful, otherwise it returns (size_t)-1.
Portability
wcsrtombs is defined by C99 standard.
wcsnrtombs is defined by the POSIX.1-2008 standard.
Next: wcstol, wcstol_l—wide string to long, Previous: wcsrtombs, wcsnrtombs—convert a wide-character string to a character string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcstod, wcstof, wcstold, wcstod_l, wcstof_l, wcstold_l—wide char string to double or floatSynopsis
#include <stdlib.h>
double wcstod(const wchar_t *__restrict str,
wchar_t **__restrict tail);
float wcstof(const wchar_t *__restrict str,
wchar_t **__restrict tail);
long double wcstold(const wchar_t *__restrict str,
wchar_t **__restrict tail);
#include <stdlib.h>
double wcstod_l(const wchar_t *__restrict str,
wchar_t **__restrict tail, locale_t locale);
float wcstof_l(const wchar_t *__restrict str,
wchar_t **__restrict tail, locale_t locale);
long double wcstold_l(const wchar_t *__restrict str,
wchar_t **__restrict tail,
locale_t locale);
double _wcstod_r(void *reent,
const wchar_t *str, wchar_t **tail);
float _wcstof_r(void *reent,
const wchar_t *str, wchar_t **tail);
Description
wcstod, wcstof, wcstold parse the wide-character string
str, producing a substring which can be converted to a double,
float, or long double value. The substring converted is the longest
initial subsequence of str, beginning with the first non-whitespace
character, that has one of these formats:
[+|-]digits[.[digits]][(e|E)[+|-]digits] [+|-].digits[(e|E)[+|-]digits] [+|-](i|I)(n|N)(f|F)[(i|I)(n|N)(i|I)(t|T)(y|Y)] [+|-](n|N)(a|A)(n|N)[<(>[hexdigits]<)>] [+|-]0(x|X)hexdigits[.[hexdigits]][(p|P)[+|-]digits] [+|-]0(x|X).hexdigits[(p|P)[+|-]digits]
The substring contains no characters if str is empty, consists
entirely of whitespace, or if the first non-whitespace
character is something other than +, -, ., or a
digit, and cannot be parsed as infinity or NaN. If the platform
does not support NaN, then NaN is treated as an empty substring.
If the substring is empty, no conversion is done, and
the value of str is stored in *tail. Otherwise,
the substring is converted, and a pointer to the final string
(which will contain at least the terminating null character of
str) is stored in *tail. If you want no
assignment to *tail, pass a null pointer as tail.
This implementation returns the nearest machine number to the
input decimal string. Ties are broken by using the IEEE
round-even rule. However, wcstof is currently subject to
double rounding errors.
wcstod_l, wcstof_l, wcstold_l are like wcstod,
wcstof, wcstold but perform the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is
undefined.
The alternate functions _wcstod_r and _wcstof_r are
reentrant versions of wcstod and wcstof, respectively.
The extra argument reent is a pointer to a reentrancy structure.
Returns
Return the converted substring value, if any. If
no conversion could be performed, 0 is returned. If the
correct value is out of the range of representable values,
plus or minus HUGE_VAL is returned, and ERANGE is
stored in errno. If the correct value would cause underflow, 0
is returned and ERANGE is stored in errno.
Portability
wcstod is ANSI.
wcstof, wcstold are C99.
wcstod_l, wcstof_l, wcstold_l are GNU extensions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: wcstoll, wcstoll_l—wide string to long long, Previous: wcstod, wcstof, wcstold, wcstod_l, wcstof_l, wcstold_l—wide char string to double or float, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcstol, wcstol_l—wide string to longSynopsis
#include <wchar.h>
long wcstol(const wchar_t *__restrict s,
wchar_t **__restrict ptr, int base);
#include <wchar.h>
long wcstol_l(const wchar_t *__restrict s,
wchar_t **__restrict ptr, int base,
locale_t locale);
long _wcstol_r(void *reent, const wchar_t *s,
wchar_t **ptr, int base);
Description
The function wcstol converts the wide string *s to
a long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of characters resembling an integer in the radix specified by base;
and a trailing portion consisting of zero or more unparseable characters,
and always including the terminating null character. Then, it attempts
to convert the subject string into a long and returns the
result.
If the value of base is 0, the subject string is expected to look
like a normal C integer constant: an optional sign, a possible ‘0x’
indicating a hexadecimal base, and a number. If base is between
2 and 36, the expected form of the subject is a sequence of letters
and digits representing an integer in the radix specified by base,
with an optional plus or minus sign. The letters a–z (or,
equivalently, A–Z) are used to signify values from 10 to 35;
only letters whose ascribed values are less than base are
permitted. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible letter or digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
wcstol attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. If the subject string begins with
a minus sign, the value is negated. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (or not in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
The alternate function _wcstol_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
wcstol_l is like wcstol but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
wcstol, wcstol_l return the converted value, if any. If no
conversion was made, 0 is returned.
wcstol, wcstol_l return LONG_MAX or LONG_MIN if the
magnitude of the converted value is too large, and sets errno
to ERANGE.
Portability
wcstol is ANSI.
wcstol_l is a GNU extension.
No supporting OS subroutines are required.
Next: wcstoul, wcstoul_l—wide string to unsigned long, Previous: wcstol, wcstol_l—wide string to long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcstoll, wcstoll_l—wide string to long longSynopsis
#include <wchar.h>
long long wcstoll(const wchar_t *__restrict s,
wchar_t **__restrict ptr,int base);
#include <wchar.h>
long long wcstoll_l(const wchar_t *__restrict s,
wchar_t **__restrict ptr, int base,
locale_t locale);
long long _wcstoll_r(void *reent, const wchar_t *s,
wchar_t **ptr, int base);
Description
The function wcstoll converts the wide string *s to
a long long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of characters resembling an integer in the radix specified by base;
and a trailing portion consisting of zero or more unparseable characters,
and always including the terminating null character. Then, it attempts
to convert the subject string into a long long and returns the
result.
If the value of base is 0, the subject string is expected to look
like a normal C integer constant: an optional sign, a possible ‘0x’
indicating a hexadecimal base, and a number. If base is between
2 and 36, the expected form of the subject is a sequence of letters
and digits representing an integer in the radix specified by base,
with an optional plus or minus sign. The letters a–z (or,
equivalently, A–Z) are used to signify values from 10 to 35;
only letters whose ascribed values are less than base are
permitted. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible letter or digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
wcstoll attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. If the subject string begins with
a minus sign, the value is negated. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (or not in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
The alternate function _wcstoll_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
wcstoll_l is like wcstoll but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
wcstoll, wcstoll_l return the converted value, if any. If no
conversion was made, 0 is returned.
wcstoll, wcstoll_l return LONG_LONG_MAX or LONG_LONG_MIN
if the magnitude of the converted value is too large, and sets errno
to ERANGE.
Portability
wcstoll is ANSI.
wcstoll_l is a GNU extension.
No supporting OS subroutines are required.
Next: wcstoull, wcstoull_l—wide string to unsigned long long, Previous: wcstoll, wcstoll_l—wide string to long long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcstoul, wcstoul_l—wide string to unsigned longSynopsis
#include <wchar.h>
unsigned long wcstoul(const wchar_t *__restrict s,
wchar_t **__restrict ptr, int base);
#include <wchar.h>
unsigned long wcstoul_l(const wchar_t *__restrict s,
wchar_t **__restrict ptr, int base,
locale_t locale);
unsigned long _wcstoul_r(void *reent, const wchar_t *s,
wchar_t **ptr, int base);
Description
The function wcstoul converts the wide string *s to
an unsigned long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of the digits meaningful in the radix specified by base
(for example, 0 through 7 if the value of base is 8);
and a trailing portion consisting of one or more unparseable characters,
which always includes the terminating null character. Then, it attempts
to convert the subject string into an unsigned long integer, and returns the
result.
If the value of base is zero, the subject string is expected to look
like a normal C integer constant (save that no optional sign is permitted):
a possible 0x indicating hexadecimal radix, and a number.
If base is between 2 and 36, the expected form of the subject is a
sequence of digits (which may include letters, depending on the
base) representing an integer in the radix specified by base.
The letters a–z (or A–Z) are used as digits valued from
10 to 35. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
wcstoul attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (that is, if *s does not start
with a substring in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
The alternate function _wcstoul_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
wcstoul_l is like wcstoul but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
wcstoul, wcstoul_l return the converted value, if any. If no
conversion was made, 0 is returned.
wcstoul, wcstoul_l return ULONG_MAX if the magnitude of the
converted value is too large, and sets errno to ERANGE.
Portability
wcstoul is ANSI.
wcstoul_l is a GNU extension.
wcstoul requires no supporting OS subroutines.
Next: system—execute command string, Previous: wcstoul, wcstoul_l—wide string to unsigned long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcstoull, wcstoull_l—wide string to unsigned long longSynopsis
#include <wchar.h>
unsigned long long wcstoull(const wchar_t *__restrict s,
wchar_t **__restrict ptr,
int base);
#include <wchar.h>
unsigned long long wcstoull_l(const wchar_t *__restrict s,
wchar_t **__restrict ptr,
int base,
locale_t locale);
unsigned long long _wcstoull_r(void *reent, const wchar_t *s,
wchar_t **ptr, int base);
Description
The function wcstoull converts the wide string *s to
an unsigned long long. First, it breaks down the string into three parts:
leading whitespace, which is ignored; a subject string consisting
of the digits meaningful in the radix specified by base
(for example, 0 through 7 if the value of base is 8);
and a trailing portion consisting of one or more unparseable characters,
which always includes the terminating null character. Then, it attempts
to convert the subject string into an unsigned long long integer, and returns the
result.
If the value of base is zero, the subject string is expected to look
like a normal C integer constant: an optional sign (+ or -),
a possible 0x indicating hexadecimal radix or a possible <0> indicating
octal radix, and a number.
If base is between 2 and 36, the expected form of the subject is a
sequence of digits (which may include letters, depending on the
base) representing an integer in the radix specified by base.
The letters a–z (or A–Z) are used as digits valued from
10 to 35. If base is 16, a leading 0x is permitted.
The subject sequence is the longest initial sequence of the input string that has the expected form, starting with the first non-whitespace character. If the string is empty or consists entirely of whitespace, or if the first non-whitespace character is not a permissible digit, the subject string is empty.
If the subject string is acceptable, and the value of base is zero,
wcstoull attempts to determine the radix from the input string. A
string with a leading 0x is treated as a hexadecimal value; a string with
a leading 0 and no x is treated as octal; all other strings are
treated as decimal. If base is between 2 and 36, it is used as the
conversion radix, as described above. Finally, a pointer to the first
character past the converted subject string is stored in ptr, if
ptr is not NULL.
If the subject string is empty (that is, if *s does not start
with a substring in acceptable form), no conversion
is performed and the value of s is stored in ptr (if ptr is
not NULL).
The alternate function _wcstoull_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
wcstoull_l is like wcstoull but performs the conversion based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
wcstoull, wcstoull_l return 0 and sets errno to EINVAL
if the value of base is not supported.
wcstoull, wcstoull_l return the converted value, if any. If no
conversion was made, 0 is returned.
wcstoull, wcstoull_l return ULLONG_MAX if the magnitude of
the converted value is too large, and sets errno to ERANGE.
Portability
wcstoull is ANSI.
wcstoull_l is a GNU extension.
wcstoull requires no supporting OS subroutines.
Next: utoa—unsigned integer to string, Previous: wcstoull, wcstoull_l—wide string to unsigned long long, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
system—execute command stringSynopsis
#include <stdlib.h> int system(char *s); int _system_r(void *reent, char *s);
Description
Use system to pass a command string *s to /bin/sh on
your system, and wait for it to finish executing.
Use “system(NULL)” to test whether your system has /bin/sh
available.
The alternate function _system_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
system(NULL) returns a non-zero value if /bin/sh is available, and
0 if it is not.
With a command argument, the result of system is the exit status
returned by /bin/sh.
Portability
ANSI C requires system, but leaves the nature and effects of a
command processor undefined. ANSI C does, however, specify that
system(NULL) return zero or nonzero to report on the existence of
a command processor.
POSIX.2 requires system, and requires that it invoke a sh.
Where sh is found is left unspecified.
Supporting OS subroutines required: _exit, _execve, _fork_r,
_wait_r.
Next: wcstombs—minimal wide char string to multibyte string converter, Previous: system—execute command string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
utoa—unsigned integer to stringSynopsis
#include <stdlib.h> char *utoa(unsigned value, char *str, int base); char *__utoa(unsigned value, char *str, int base);
Description
utoa converts the unsigned integer [<value>] to a null-terminated string
using the specified base, which must be between 2 and 36, inclusive.
str should be an array long enough to contain the converted
value, which in the worst case is sizeof(int)*8+1 bytes.
Returns
A pointer to the string, str, or NULL if base is invalid.
Portability
utoa is non-ANSI.
No supporting OS subroutine calls are required.
Next: wctomb—minimal wide char to multibyte converter, Previous: utoa—unsigned integer to string, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wcstombs—minimal wide char string to multibyte string converterSynopsis
#include <stdlib.h> size_t wcstombs(char *restrict s, const wchar_t *restrict pwc, size_t n);
Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of wcstombs. In this case,
all wide-characters are expected to represent single bytes and so
are converted simply by casting to char.
When _MB_CAPABLE is defined, this routine calls _wcstombs_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Returns
This implementation of wcstombs returns 0 if
s is NULL or is the empty string;
it returns -1 if _MB_CAPABLE and one of the
wide-char characters does not represent a valid multi-byte character;
otherwise it returns the minimum of: n or the
number of bytes that are transferred to s, not including the
nul terminator.
If the return value is -1, the state of the pwc string is
indeterminate. If the input has a length of 0, the output
string will be modified to contain a wchar_t nul terminator if
n > 0.
Portability
wcstombs is required in the ANSI C standard. However, the precise
effects vary with the locale.
wcstombs requires no supporting OS subroutines.
Previous: wcstombs—minimal wide char string to multibyte string converter, Up: Standard Utility Functions (stdlib.h) [Contents][Index]
wctomb—minimal wide char to multibyte converterSynopsis
#include <stdlib.h> int wctomb(char *s, wchar_t wchar);
Description
When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
implementation of wctomb. The
only “wide characters” recognized are single bytes,
and they are “converted” to themselves.
When _MB_CAPABLE is defined, this routine calls _wctomb_r to perform
the conversion, passing a state variable to allow state dependent
decoding. The result is based on the locale setting which may
be restricted to a defined set of locales.
Each call to wctomb modifies *s unless s is a null
pointer or _MB_CAPABLE is defined and wchar is invalid.
Returns
This implementation of wctomb returns 0 if
s is NULL; it returns -1 if _MB_CAPABLE is enabled
and the wchar is not a valid multi-byte character, it returns 1
if _MB_CAPABLE is not defined or the wchar is in reality a single
byte character, otherwise it returns the number of bytes in the
multi-byte character.
Portability
wctomb is required in the ANSI C standard. However, the precise
effects vary with the locale.
wctomb requires no supporting OS subroutines.
Next: Input and Output (stdio.h), Previous: Standard Utility Functions (stdlib.h), Up: The Red Hat newlib C Library [Contents][Index]
This chapter groups macros (which are also available as subroutines) to classify characters into several categories (alphabetic, numeric, control characters, whitespace, and so on), or to perform simple character mappings.
The header file ctype.h defines the macros.
isalnum, isalnum_l—alphanumeric character predicateisalpha, isalpha_l—alphabetic character predicateisascii, isascii_l—ASCII character predicateisblank, isblank_l—blank character predicateiscntrl, iscntrl_l—control character predicateisdigit, isdigit_l—decimal digit predicateislower, islower_l—lowercase character predicateisprint, isgraph, isprint_l, isgraph_l—printable character predicatesispunct, ispunct_l—punctuation character predicateisspace, isspace_l—whitespace character predicateisupper, isupper_l—uppercase character predicateisxdigit, isxdigit_l—hexadecimal digit predicatetoascii, toascii_l—force integers to ASCII rangetolower, tolower_l—translate characters to lowercasetoupper, toupper_l—translate characters to uppercaseiswalnum, iswalnum_l—alphanumeric wide character testiswalpha, iswalpha_l—alphabetic wide character testiswcntrl, iswcntrl_l—control wide character testiswblank, iswblank_l—blank wide character testiswdigit, iswdigit_l—decimal digit wide character testiswgraph, iswgraph_l—graphic wide character testiswlower, iswlower_l—lowercase wide character testiswprint, iswprint_l—printable wide character testiswpunct, iswpunct_l—punctuation wide character testiswspace, iswspace_l—whitespace wide character testiswupper, iswupper_l—uppercase wide character testiswxdigit, iswxdigit_l—hexadecimal digit wide character testiswctype, iswctype_l—extensible wide-character testwctype, wctype_l—get wide-character classification typetowlower, towlower_l—translate wide characters to lowercasetowupper, towupper_l—translate wide characters to uppercasetowctrans, towctrans_l—extensible wide-character translationwctrans, wctrans_l—get wide-character translation type
Next: isalpha, isalpha_l—alphabetic character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isalnum, isalnum_l—alphanumeric character predicateSynopsis
#include <ctype.h> int isalnum(int c); #include <ctype.h> int isalnum_l(int c, locale_t locale);
Description
isalnum is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for alphabetic or
numeric ASCII characters, and 0 for other arguments. It is defined
only if c is representable as an unsigned char or if c is EOF.
isalnum_l is like isalnum but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isalnum’ or ‘#undef isalnum_l’.
Returns
isalnum,isalnum_l return non-zero if c is a letter or a digit.
Portability
isalnum is ANSI C.
isalnum_l is POSIX-1.2008.
No OS subroutines are required.
Next: isascii, isascii_l—ASCII character predicate, Previous: isalnum, isalnum_l—alphanumeric character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isalpha, isalpha_l—alphabetic character predicateSynopsis
#include <ctype.h> int isalpha(int c); #include <ctype.h> int isalpha_l(int c, locale_t locale);
Description
isalpha is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero when c represents an
alphabetic ASCII character, and 0 otherwise. It is defined only if
c is representable as an unsigned char or if c is EOF.
isalpha_l is like isalpha but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isalpha’ or ‘#undef isalpha_l’.
Returns
isalpha, isalpha_l return non-zero if c is a letter.
Portability
isalpha is ANSI C.
isalpha_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: isblank, isblank_l—blank character predicate, Previous: isalpha, isalpha_l—alphabetic character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isascii, isascii_l—ASCII character predicateSynopsis
#include <ctype.h> int isascii(int c); #include <ctype.h> int isascii_l(int c, locale_t locale);
Description
isascii is a macro which returns non-zero when c is an ASCII
character, and 0 otherwise. It is defined for all integer values.
isascii_l is like isascii but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isascii’ or ‘#undef isascii_l’.
Returns
isascii, isascii_l return non-zero if the low order byte of c
is in the range 0 to 127 (0x00–0x7F).
Portability
isascii is ANSI C.
isascii_l is a GNU extension.
No supporting OS subroutines are required.
Next: iscntrl, iscntrl_l—control character predicate, Previous: isascii, isascii_l—ASCII character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isblank, isblank_l—blank character predicateSynopsis
#include <ctype.h> int isblank(int c); #include <ctype.h> int isblank_l(int c, locale_t locale);
Description
isblank is a function which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for blank characters, and 0
for other characters. It is defined only if c is representable as an
unsigned char or if c is EOF.
isblank_l is like isblank but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
isblank, isblank_l return non-zero if c is a blank character.
Portability
isblank is C99.
isblank_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: isdigit, isdigit_l—decimal digit predicate, Previous: isblank, isblank_l—blank character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iscntrl, iscntrl_l—control character predicateSynopsis
#include <ctype.h> int iscntrl(int c); #include <ctype.h> int iscntrl_l(int c, locale_t locale);
Description
iscntrl is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for control characters, and 0
for other characters. It is defined only if c is representable as an
unsigned char or if c is EOF.
iscntrl_l is like iscntrl but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef iscntrl’ or ‘#undef iscntrl_l’.
Returns
iscntrl, iscntrl_l return non-zero if c is a delete character
or ordinary control character.
Portability
iscntrl is ANSI C.
iscntrl_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: islower, islower_l—lowercase character predicate, Previous: iscntrl, iscntrl_l—control character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isdigit, isdigit_l—decimal digit predicateSynopsis
#include <ctype.h> int isdigit(int c); #include <ctype.h> int isdigit_l(int c, locale_t locale);
Description
isdigit is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for decimal digits, and 0 for
other characters. It is defined only if c is representable as an
unsigned char or if c is EOF.
isdigit_l is like isdigit but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isdigit’ or ‘#undef isdigit_l’.
Returns
isdigit, isdigit_l return non-zero if c is a decimal digit
(0–9).
Portability
isdigit is ANSI C.
isdigit_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: isprint, isgraph, isprint_l, isgraph_l—printable character predicates, Previous: isdigit, isdigit_l—decimal digit predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
islower, islower_l—lowercase character predicateSynopsis
#include <ctype.h> int islower(int c); #include <ctype.h> int islower_l(int c, locale_t locale);
Description
islower is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for minuscules
(lowercase alphabetic characters), and 0 for other characters.
It is defined only if c is representable as an unsigned char or if
c is EOF.
islower_l is like islower but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef islower’ or ‘#undef islower_l’.
Returns
islower, islower_l return non-zero if c is a lowercase letter.
Portability
islower is ANSI C.
islower_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: ispunct, ispunct_l—punctuation character predicate, Previous: islower, islower_l—lowercase character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isprint, isgraph, isprint_l, isgraph_l—printable character predicatesSynopsis
#include <ctype.h> int isprint(int c); int isgraph(int c); #include <ctype.h> int isprint_l(int c, locale_t locale); int isgraph_l(int c, locale_t locale);
Description
isprint is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for printable characters,
and 0 for other character arguments. It is defined only if c is
representable as an unsigned char or if c is EOF.
isgraph behaves identically to isprint, except that space characters
are excluded.
isprint_l, isgraph_l are like isprint, isgraph but perform
the check based on the locale specified by the locale object locale. If
locale is LC_GLOBAL_LOCALE or not a valid locale object, the behaviour
is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining either macro using ‘#undef isprint’ or ‘#undef isgraph’,
or ‘#undef isprint_l’ or ‘#undef isgraph_l’.
Returns
isprint, isprint_l return non-zero if c is a printing character.
isgraph, isgraph_l return non-zero if c is a printing character
except spaces.
Portability
isprint and isgraph are ANSI C.
No supporting OS subroutines are required.
Next: isspace, isspace_l—whitespace character predicate, Previous: isprint, isgraph, isprint_l, isgraph_l—printable character predicates, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
ispunct, ispunct_l—punctuation character predicateSynopsis
#include <ctype.h> int ispunct(int c); #include <ctype.h> int ispunct_l(int c, locale_t locale);
Description
ispunct is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for printable
punctuation characters, and 0 for other characters. It is defined only
if c is representable as an unsigned char or if c is EOF.
ispunct_l is like ispunct but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef ispunct’ or ‘#undef ispunct_l’.
Returns
ispunct, ispunct_l return non-zero if c is a printable
punctuation character.
Portability
ispunct is ANSI C.
ispunct_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: isupper, isupper_l—uppercase character predicate, Previous: ispunct, ispunct_l—punctuation character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isspace, isspace_l—whitespace character predicateSynopsis
#include <ctype.h> int isspace(int c); #include <ctype.h> int isspace_l(int c, locale_t locale);
Description
isspace is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for whitespace
characters, and 0 for other characters. It is defined only when isascii(c) is true or c is EOF.
isspace_l is like isspace but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isspace’ or ‘#undef isspace_l’.
Returns
isspace, isspace_l return non-zero if c is a space, tab,
carriage return, new line, vertical tab, or formfeed (0x09–0x0D,
0x20), or one of the other space characters in non-ASCII charsets.
Portability
isspace is ANSI C.
isspace_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: isxdigit, isxdigit_l—hexadecimal digit predicate, Previous: isspace, isspace_l—whitespace character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isupper, isupper_l—uppercase character predicateSynopsis
#include <ctype.h> int isupper(int c); #include <ctype.h> int isupper_l(int c, locale_t locale);
Description
isupper is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for uppercase letters
(A–Z), and 0 for other characters.
isupper_l is like isupper but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isupper’ or ‘#undef isupper_l’.
Returns
isupper, isupper_l return non-zero if c is an uppercase letter.
Portability
isupper is ANSI C.
isupper_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: toascii, toascii_l—force integers to ASCII range, Previous: isupper, isupper_l—uppercase character predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
isxdigit, isxdigit_l—hexadecimal digit predicateSynopsis
#include <ctype.h> int isxdigit(int c); #include <ctype.h> int isxdigit_l(int c, locale_t locale);
Description
isxdigit is a macro which classifies singlebyte charset values by table
lookup. It is a predicate returning non-zero for hexadecimal digits,
and 0 for other characters. It is defined only if c is
representable as an unsigned char or if c is EOF.
isxdigit_l is like isxdigit but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining the macro using ‘#undef isxdigit’ or ‘#undef isxdigit_l’.
Returns
isxdigit, isxdigit_l return non-zero if c is a hexadecimal digit
(0–9, a–f, or A–F).
Portability
isxdigit is ANSI C.
isxdigit_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: tolower, tolower_l—translate characters to lowercase, Previous: isxdigit, isxdigit_l—hexadecimal digit predicate, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
toascii, toascii_l—force integers to ASCII rangeSynopsis
#include <ctype.h> int toascii(int c); #include <ctype.h> int toascii_l(int c, locale_t locale);
Description
toascii is a macro which coerces integers to the ASCII range (0–127) by zeroing any higher-order bits.
toascii_l is like toascii but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining this macro using ‘#undef toascii’ or ‘#undef toascii_l’.
Returns
toascii, toascii_l return integers between 0 and 127.
Portability
toascii is X/Open, BSD and POSIX-1.2001, but marked obsolete in
POSIX-1.2008.
toascii_l is a GNU extension.
No supporting OS subroutines are required.
Next: toupper, toupper_l—translate characters to uppercase, Previous: toascii, toascii_l—force integers to ASCII range, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
tolower, tolower_l—translate characters to lowercaseSynopsis
#include <ctype.h> int tolower(int c); int _tolower(int c); #include <ctype.h> int tolower_l(int c, locale_t locale);
Description
tolower is a macro which converts uppercase characters to lowercase,
leaving all other characters unchanged. It is only defined when
c is an integer in the range EOF to 255.
tolower_l is like tolower but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining this macro using ‘#undef tolower’ or ‘#undef tolower_l’.
_tolower performs the same conversion as tolower, but should
only be used when c is known to be an uppercase character (A–Z).
Returns
tolower, tolower_l return the lowercase equivalent of c when
c is an uppercase character, and c otherwise.
_tolower returns the lowercase equivalent of c when it is a
character between A and Z. If c is not one of these
characters, the behaviour of _tolower is undefined.
Portability
tolower is ANSI C. _tolower is not recommended for portable programs.
tolower_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswalnum, iswalnum_l—alphanumeric wide character test, Previous: tolower, tolower_l—translate characters to lowercase, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
toupper, toupper_l—translate characters to uppercaseSynopsis
#include <ctype.h> int toupper(int c); int _toupper(int c); #include <ctype.h> int toupper_l(int c, locale_t locale);
Description
toupper is a macro which converts lowercase characters to uppercase,
leaving all other characters unchanged. It is only defined when
c is an integer in the range EOF to 255.
toupper_l is like toupper but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
You can use a compiled subroutine instead of the macro definition by
undefining this macro using ‘#undef toupper’ or ‘#undef toupper_l’.
_toupper performs the same conversion as toupper, but should
only be used when c is known to be a lowercase character (a–z).
Returns
toupper, toupper_l return the uppercase equivalent of c when
c is a lowercase character, and c otherwise.
_toupper returns the uppercase equivalent of c when it is a
character between a and z. If c is not one of these
characters, the behaviour of _toupper is undefined.
Portability
toupper is ANSI C. _toupper is not recommended for portable programs.
toupper_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswalpha, iswalpha_l—alphabetic wide character test, Previous: toupper, toupper_l—translate characters to uppercase, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswalnum, iswalnum_l—alphanumeric wide character testSynopsis
#include <wctype.h> int iswalnum(wint_t c); #include <wctype.h> int iswalnum_l(wint_t c, locale_t locale);
Description
iswalnum is a function which classifies wide-character values that
are alphanumeric.
iswalnum_l is like iswalnum but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswalnum, iswalnum_l return non-zero if c is a alphanumeric
wide character.
Portability
iswalnum is C99.
iswalnum_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswcntrl, iswcntrl_l—control wide character test, Previous: iswalnum, iswalnum_l—alphanumeric wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswalpha, iswalpha_l—alphabetic wide character testSynopsis
#include <wctype.h> int iswalpha(wint_t c); #include <wctype.h> int iswalpha_l(wint_t c, locale_t locale);
Description
iswalpha is a function which classifies wide-character values that
are alphabetic.
iswalpha_l is like iswalpha but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswalpha, iswalpha_l return non-zero if c is an alphabetic
wide character.
Portability
iswalpha is C99.
iswalpha_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswblank, iswblank_l—blank wide character test, Previous: iswalpha, iswalpha_l—alphabetic wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswcntrl, iswcntrl_l—control wide character testSynopsis
#include <wctype.h> int iswcntrl(wint_t c); #include <wctype.h> int iswcntrl_l(wint_t c, locale_t locale);
Description
iswcntrl is a function which classifies wide-character values that
are categorized as control characters.
iswcntrl_l is like iswcntrl but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswcntrl, iswcntrl_l return non-zero if c is a control wide character.
Portability
iswcntrl is C99.
iswcntrl_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswdigit, iswdigit_l—decimal digit wide character test, Previous: iswcntrl, iswcntrl_l—control wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswblank, iswblank_l—blank wide character testSynopsis
#include <wctype.h> int iswblank(wint_t c); #include <wctype.h> int iswblank_l(wint_t c, locale_t locale);
Description
iswblank is a function which classifies wide-character values that
are categorized as blank.
iswblank_l is like iswblank but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswblank, iswblank_l return non-zero if c is a blank wide character.
Portability
iswblank is C99.
iswblank_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswgraph, iswgraph_l—graphic wide character test, Previous: iswblank, iswblank_l—blank wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswdigit, iswdigit_l—decimal digit wide character testSynopsis
#include <wctype.h> int iswdigit(wint_t c); #include <wctype.h> int iswdigit_l(wint_t c, locale_t locale);
Description
iswdigit is a function which classifies wide-character values that
are decimal digits.
iswdigit_l is like iswdigit but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswdigit, iswdigit_l return non-zero if c is a decimal digit wide character.
Portability
iswdigit is C99.
iswdigit_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswlower, iswlower_l—lowercase wide character test, Previous: iswdigit, iswdigit_l—decimal digit wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswgraph, iswgraph_l—graphic wide character testSynopsis
#include <wctype.h> int iswgraph(wint_t c); #include <wctype.h> int iswgraph_l(wint_t c, locale_t locale);
Description
iswgraph is a function which classifies wide-character values that
are graphic.
iswgraph_l is like iswgraph but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswgraph, iswgraph_l return non-zero if c is a graphic wide character.
Portability
iswgraph is C99.
iswgraph_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswprint, iswprint_l—printable wide character test, Previous: iswgraph, iswgraph_l—graphic wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswlower, iswlower_l—lowercase wide character testSynopsis
#include <wctype.h> int iswlower(wint_t c); #include <wctype.h> int iswlower_l(wint_t c, locale_t locale);
Description
iswlower is a function which classifies wide-character values that
are categorized as lowercase.
iswlower_l is like iswlower but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswlower, iswlower_l return non-zero if c is a lowercase wide character.
Portability
iswlower is C99.
iswlower_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswpunct, iswpunct_l—punctuation wide character test, Previous: iswlower, iswlower_l—lowercase wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswprint, iswprint_l—printable wide character testSynopsis
#include <wctype.h> int iswprint(wint_t c); #include <wctype.h> int iswprint_l(wint_t c, locale_t locale);
Description
iswprint is a function which classifies wide-character values that
are printable.
iswprint_l is like iswprint but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswprint, iswprint_l return non-zero if c is a printable wide character.
Portability
iswprint is C99.
iswprint_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswspace, iswspace_l—whitespace wide character test, Previous: iswprint, iswprint_l—printable wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswpunct, iswpunct_l—punctuation wide character testSynopsis
#include <wctype.h> int iswpunct(wint_t c); #include <wctype.h> int iswpunct_l(wint_t c, locale_t locale);
Description
iswpunct is a function which classifies wide-character values that
are punctuation.
iswpunct_l is like iswpunct but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswpunct, iswpunct_l return non-zero if c is a punctuation wide character.
Portability
iswpunct is C99.
iswpunct_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswupper, iswupper_l—uppercase wide character test, Previous: iswpunct, iswpunct_l—punctuation wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswspace, iswspace_l—whitespace wide character testSynopsis
#include <wctype.h> int iswspace(wint_t c); #include <wctype.h> int iswspace_l(wint_t c, locale_t locale);
Description
iswspace is a function which classifies wide-character values that
are categorized as whitespace.
iswspace_l is like iswspace but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswspace, iswspace_l return non-zero if c is a whitespace wide character.
Portability
iswspace is C99.
iswspace_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswxdigit, iswxdigit_l—hexadecimal digit wide character test, Previous: iswspace, iswspace_l—whitespace wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswupper, iswupper_l—uppercase wide character testSynopsis
#include <wctype.h> int iswupper(wint_t c); #include <wctype.h> int iswupper_l(wint_t c, locale_t locale);
Description
iswupper is a function which classifies wide-character values that
are categorized as uppercase.
iswupper_l is like iswupper but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswupper, iswupper_l return non-zero if c is an uppercase wide character.
Portability
iswupper is C99.
iswupper_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: iswctype, iswctype_l—extensible wide-character test, Previous: iswupper, iswupper_l—uppercase wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswxdigit, iswxdigit_l—hexadecimal digit wide character testSynopsis
#include <wctype.h> int iswxdigit(wint_t c); #include <wctype.h> int iswxdigit_l(wint_t c, locale_t locale);
Description
iswxdigit is a function which classifies wide character values that
are hexadecimal digits.
iswxdigit_l is like iswxdigit but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswxdigit, iswxdigit_l return non-zero if c is a hexadecimal digit wide character.
Portability
iswxdigit is C99.
iswxdigit_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: wctype, wctype_l—get wide-character classification type, Previous: iswxdigit, iswxdigit_l—hexadecimal digit wide character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
iswctype, iswctype_l—extensible wide-character testSynopsis
#include <wctype.h> int iswctype(wint_t c, wctype_t desc); #include <wctype.h> int iswctype_l(wint_t c, wctype_t desc, locale_t locale);
Description
iswctype is a function which classifies wide-character values using the
wide-character test specified by desc.
iswctype_l is like iswctype but performs the check based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
iswctype, iswctype_l return non-zero if and only if c matches
the test specified by desc. If desc is unknown, zero is returned.
Portability
iswctype is C99.
iswctype_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: towlower, towlower_l—translate wide characters to lowercase, Previous: iswctype, iswctype_l—extensible wide-character test, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
wctype, wctype_l—get wide-character classification typeSynopsis
#include <wctype.h> wctype_t wctype(const char *c); #include <wctype.h> wctype_t wctype_l(const char *c, locale_t locale);
Description
wctype is a function which takes a string c and gives back
the appropriate wctype_t type value associated with the string,
if one exists. The following values are guaranteed to be recognized:
"alnum", "alpha", "blank", "cntrl", "digit", "graph", "lower", "print",
"punct", "space", "upper", and "xdigit".
wctype_l is like wctype but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
wctype, wctype_l return 0 and sets errno to EINVAL if the
given name is invalid. Otherwise, it returns a valid non-zero wctype_t
value.
Portability
wctype is C99.
wctype_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: towupper, towupper_l—translate wide characters to uppercase, Previous: wctype, wctype_l—get wide-character classification type, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
towlower, towlower_l—translate wide characters to lowercaseSynopsis
#include <wctype.h> wint_t towlower(wint_t c); #include <wctype.h> wint_t towlower_l(wint_t c, locale_t locale);
Description
towlower is a function which converts uppercase wide characters to
lowercase, leaving all other characters unchanged.
towlower_l is like towlower but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
towlower, towlower_l return the lowercase equivalent of c when it is a
uppercase wide character; otherwise, it returns the input character.
Portability
towlower is C99.
towlower_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: towctrans, towctrans_l—extensible wide-character translation, Previous: towlower, towlower_l—translate wide characters to lowercase, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
towupper, towupper_l—translate wide characters to uppercaseSynopsis
#include <wctype.h> wint_t towupper(wint_t c); #include <wctype.h> wint_t towupper_l(wint_t c, locale_t locale);
Description
towupper is a function which converts lowercase wide characters to
uppercase, leaving all other characters unchanged.
towupper_l is like towupper but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
towupper, towupper_l return the uppercase equivalent of c when it is a
lowercase wide character, otherwise, it returns the input character.
Portability
towupper is C99.
towupper_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: wctrans, wctrans_l—get wide-character translation type, Previous: towupper, towupper_l—translate wide characters to uppercase, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
towctrans, towctrans_l—extensible wide-character translationSynopsis
#include <wctype.h> wint_t towctrans(wint_t c, wctrans_t w); #include <wctype.h> wint_t towctrans_l(wint_t c, wctrans_t w, locale_t locale);
Description
towctrans is a function which converts wide characters based on
a specified translation type w. If the translation type is
invalid or cannot be applied to the current character, no change
to the character is made.
towctrans_l is like towctrans but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
towctrans, towctrans_l return the translated equivalent of c
when it is a valid for the given translation, otherwise, it returns the
input character. When the translation type is invalid, errno is
set to EINVAL.
Portability
towctrans is C99.
towctrans_l is POSIX-1.2008.
No supporting OS subroutines are required.
Previous: towctrans, towctrans_l—extensible wide-character translation, Up: Character Type Macros and Functions (ctype.h) [Contents][Index]
wctrans, wctrans_l—get wide-character translation typeSynopsis
#include <wctype.h> wctrans_t wctrans(const char *c); #include <wctype.h> wctrans_t wctrans_l(const char *c, locale_t locale);
Description
wctrans is a function which takes a string c and gives back
the appropriate wctrans_t type value associated with the string,
if one exists. The following values are guaranteed to be recognized:
"tolower" and "toupper".
wctrans_l is like wctrans but performs the function based on the
locale specified by the locale object locale. If locale is
LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
Returns
wctrans, wctrans_l return 0 and sets errno to EINVAL if the
given name is invalid. Otherwise, it returns a valid non-zero wctrans_t
value.
Portability
wctrans is C99.
wctrans_l is POSIX-1.2008.
No supporting OS subroutines are required.
Next: Large File Input and Output (stdio.h), Previous: Character Type Macros and Functions (ctype.h), Up: The Red Hat newlib C Library [Contents][Index]
This chapter comprises functions to manage files or other input/output streams. Among these functions are subroutines to generate or scan strings according to specifications from a format string.
The underlying facilities for input and output depend on the host system, but these functions provide a uniform interface.
The corresponding declarations are in stdio.h.
The reentrant versions of these functions use macros
_stdin_r(reent) _stdout_r(reent) _stderr_r(reent)
instead of the globals stdin, stdout, and
stderr. The argument reent is a pointer to a reentrancy
structure.
clearerr, clearerr_unlocked—clear file or stream error indicatordiprintf, vdiprintf—print to a file descriptor (integer only)dprintf, vdprintf—print to a file descriptorfclose—close a filefcloseall—close all filesfdopen—turn open file into a streamfeof, feof_unlocked—test for end of fileferror, ferror_unlocked—test whether read/write error has occurredfflush, fflush_unlocked—flush buffered file outputfgetc, fgetc_unlocked—get a character from a file or streamfgetpos—record position in a stream or filefgets, fgets_unlocked—get character string from a file or streamfgetwc, getwc, fgetwc_unlocked, getwc_unlocked—get a wide character from a file or streamfgetws, fgetws_unlocked—get wide character string from a file or streamfileno, fileno_unlocked—return file descriptor associated with streamfmemopen—open a stream around a fixed-length stringfopen—open a filefopencookie—open a stream with custom callbacksfpurge—discard pending file I/Ofputc, fputc_unlocked—write a character on a stream or filefputs, fputs_unlocked—write a character string in a file or streamfputwc, putwc, fputwc_unlocked, putwc_unlocked—write a wide character on a stream or filefputws, fputws_unlocked—write a wide character string in a file or streamfread, fread_unlocked—read array elements from a filefreopen—open a file using an existing file descriptorfseek, fseeko—set file position__fsetlocking—set or query locking mode on FILE streamfsetpos—restore position of a stream or fileftell, ftello—return position in a stream or filefunopen, fropen, fwopen—open a stream with custom callbacksfwide—set and determine the orientation of a FILE streamfwrite, fwrite_unlocked—write array elementsgetc—read a character (macro)getc_unlocked—non-thread-safe version of getc (macro)getchar—read a character (macro)getchar_unlocked—non-thread-safe version of getchar (macro)getdelim—read a line up to a specified line delimitergetline—read a line from a filegets—get character string (obsolete, use fgets instead)getw—read a word (int)getwchar, getwchar_unlocked—read a wide character from standard inputmktemp, mkstemp, mkostemp, mkstemps,open_memstream, open_wmemstream—open a write stream around an arbitrary-length stringperror—print an error message on standard errorputc—write a character (macro)putc_unlocked—non-thread-safe version of putc (macro)putchar—write a character (macro)putchar_unlocked—non-thread-safe version of putchar (macro)puts—write a character stringputw—write a word (int)putwchar, putwchar_unlocked—write a wide character to standard outputremove—delete a file’s namerename—rename a filerewind—reinitialize a file or streamsetbuf—specify full buffering for a file or streamsetbuffer—specify full buffering for a file or stream with sizesetlinebuf—specify line buffering for a file or streamsetvbuf—specify file or stream bufferingsiprintf, fiprintf, iprintf, sniprintf, asiprintf, asniprintf—format output (integer only)siscanf, fiscanf, iscanf—scan and format non-floating inputsprintf, fprintf, printf, snprintf, asprintf, asnprintf—format outputsscanf, fscanf, scanf—scan and format inputstdio_ext,__fbufsize,__fpending,__flbf,__freadable,__fwritable,__freading,__fwriting—access internals of FILE structureswprintf, fwprintf, wprintf—wide character format outputswscanf, fwscanf, wscanf—scan and format wide character inputtmpfile—create a temporary filetmpnam, tempnam—name for a temporary fileungetc—push data back into a streamungetwc—push wide character data back into a streamvfprintf, vprintf, vsprintf, vsnprintf, vasprintf, vasnprintf—format argument listvfscanf, vscanf, vsscanf—format argument listvfwprintf, vwprintf, vswprintf—wide character format argument listvfwscanf, vwscanf, vswscanf—scan and format argument list from wide character inputviprintf, vfiprintf, vsiprintf, vsniprintf, vasiprintf, vasniprintf—format argument list (integer only)viscanf, vfiscanf, vsiscanf—format argument list
Next: diprintf, vdiprintf—print to a file descriptor (integer only), Up: Input and Output (stdio.h) [Contents][Index]
clearerr, clearerr_unlocked—clear file or stream error indicatorSynopsis
#include <stdio.h> void clearerr(FILE *fp); #define _BSD_SOURCE #include <stdio.h> void clearerr_unlocked(FILE *fp);
Description
The stdio functions maintain an error indicator with each file
pointer fp, to record whether any read or write errors have
occurred on the associated file or stream. Similarly, it maintains an
end-of-file indicator to record whether there is no more data in the
file.
Use clearerr to reset both of these indicators.
See ferror and feof to query the two indicators.
clearerr_unlocked is a non-thread-safe version of clearerr.
clearerr_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
clearerr_unlocked is equivalent to clearerr.
Returns
clearerr does not return a result.
Portability
ANSI C requires clearerr.
clearerr_unlocked is a BSD extension also provided by GNU libc.
No supporting OS subroutines are required.
Next: dprintf, vdprintf—print to a file descriptor, Previous: clearerr, clearerr_unlocked—clear file or stream error indicator, Up: Input and Output (stdio.h) [Contents][Index]
diprintf, vdiprintf—print to a file descriptor (integer only)Synopsis
#include <stdio.h>
#include <stdarg.h>
int diprintf(int fd, const char *format, ...);
int vdiprintf(int fd, const char *format, va_list ap);
int _diprintf_r(struct _reent *ptr, int fd,
const char *format, ...);
int _vdiprintf_r(struct _reent *ptr, int fd,
const char *format, va_list ap);
Description
diprintf and vdiprintf are similar to dprintf and vdprintf,
except that only integer format specifiers are processed.
The functions _diprintf_r and _vdiprintf_r are simply
reentrant versions of the functions above.
Returns
Similar to dprintf and vdprintf.
Portability
This set of functions is an integer-only extension, and is not portable.
Supporting OS subroutines required: sbrk, write.
Next: fclose—close a file, Previous: diprintf, vdiprintf—print to a file descriptor (integer only), Up: Input and Output (stdio.h) [Contents][Index]
dprintf, vdprintf—print to a file descriptorSynopsis
#include <stdio.h>
#include <stdarg.h>
int dprintf(int fd, const char *restrict format, ...);
int vdprintf(int fd, const char *restrict format,
va_list ap);
int _dprintf_r(struct _reent *ptr, int fd,
const char *restrict format, ...);
int _vdprintf_r(struct _reent *ptr, int fd,
const char *restrict format, va_list ap);
Description
dprintf and vdprintf allow printing a format, similarly to
printf, but write to a file descriptor instead of to a FILE
stream.
The functions _dprintf_r and _vdprintf_r are simply
reentrant versions of the functions above.
Returns
The return value and errors are exactly as for write, except that
errno may also be set to ENOMEM if the heap is exhausted.
Portability
This function is originally a GNU extension in glibc and is not portable.
Supporting OS subroutines required: sbrk, write.
Next: fcloseall—close all files, Previous: dprintf, vdprintf—print to a file descriptor, Up: Input and Output (stdio.h) [Contents][Index]
fclose—close a fileSynopsis
#include <stdio.h> int fclose(FILE *fp); int _fclose_r(struct _reent *reent, FILE *fp);
Description
If the file or stream identified by fp is open, fclose closes
it, after first ensuring that any pending data is written (by calling
fflush(fp)).
The alternate function _fclose_r is a reentrant version.
The extra argument reent is a pointer to a reentrancy structure.
Returns
fclose returns 0 if successful (including when fp is
NULL or not an open file); otherwise, it returns EOF.
Portability
fclose is required by ANSI C.
Required OS subroutines: close, fstat, isatty, lseek,
read, sbrk, write.
Next: fdopen—turn open file into a stream, Previous: fclose—close a file, Up: Input and Output (stdio.h) [Contents][Index]
fcloseall—close all filesSynopsis
#include <stdio.h> int fcloseall(void); int _fcloseall_r (struct _reent *ptr);
Description
fcloseall closes all files in the current reentrancy struct’s domain.
The function _fcloseall_r is the same function, except the reentrancy
struct is passed in as the ptr argument.
This function is not recommended as it closes all streams, including the std streams.
Returns
fclose returns 0 if all closes are successful. Otherwise,
EOF is returned.
Portability
fcloseall is a glibc extension.
Required OS subroutines: close, fstat, isatty, lseek,
read, sbrk, write.
Next: feof, feof_unlocked—test for end of file, Previous: fcloseall—close all files, Up: Input and Output (stdio.h) [Contents][Index]
fdopen—turn open file into a streamSynopsis
#include <stdio.h>
FILE *fdopen(int fd, const char *mode);
FILE *_fdopen_r(struct _reent *reent,
int fd, const char *mode);
Description
fdopen produces a file descriptor of type FILE *, from a
descriptor for an already-open file (returned, for example, by the
system subroutine open rather than by fopen).
The mode argument has the same meanings as in fopen.
Returns
File pointer or NULL, as for fopen.
Portability
fdopen is ANSI.
Next: ferror, ferror_unlocked—test whether read/write error has occurred, Previous: fdopen—turn open file into a stream, Up: Input and Output (stdio.h) [Contents][Index]
feof, feof_unlocked—test for end of fileSynopsis
#include <stdio.h> int feof(FILE *fp); #define _BSD_SOURCE #include <stdio.h> int feof_unlocked(FILE *fp);
Description
feof tests whether or not the end of the file identified by fp
has been reached.
feof_unlocked is a non-thread-safe version of feof.
feof_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
feof_unlocked is equivalent to feof.
Returns
feof returns 0 if the end of file has not yet been reached; if
at end of file, the result is nonzero.
Portability
feof is required by ANSI C.
feof_unlocked is a BSD extension also provided by GNU libc.
No supporting OS subroutines are required.
Next: fflush, fflush_unlocked—flush buffered file output, Previous: feof, feof_unlocked—test for end of file, Up: Input and Output (stdio.h) [Contents][Index]
ferror, ferror_unlocked—test whether read/write error has occurredSynopsis
#include <stdio.h> int ferror(FILE *fp); #define _BSD_SOURCE #include <stdio.h> int ferror_unlocked(FILE *fp);
Description
The stdio functions maintain an error indicator with each file
pointer fp, to record whether any read or write errors have
occurred on the associated file or stream.
Use ferror to query this indicator.
See clearerr to reset the error indicator.
ferror_unlocked is a non-thread-safe version of ferror.
ferror_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
ferror_unlocked is equivalent to ferror.
Returns
ferror returns 0 if no errors have occurred; it returns a
nonzero value otherwise.
Portability
ANSI C requires ferror.
ferror_unlocked is a BSD extension also provided by GNU libc.
No supporting OS subroutines are required.
Next: fgetc, fgetc_unlocked—get a character from a file or stream, Previous: ferror, ferror_unlocked—test whether read/write error has occurred, Up: Input and Output (stdio.h) [Contents][Index]
fflush, fflush_unlocked—flush buffered file outputSynopsis
#include <stdio.h> int fflush(FILE *fp); #define _BSD_SOURCE #include <stdio.h> int fflush_unlocked(FILE *fp); #include <stdio.h> int _fflush_r(struct _reent *reent, FILE *fp); #define _BSD_SOURCE #include <stdio.h> int _fflush_unlocked_r(struct _reent *reent, FILE *fp);
Description
The stdio output functions can buffer output before delivering it
to the host system, in order to minimize the overhead of system calls.
Use fflush to deliver any such pending output (for the file
or stream identified by fp) to the host system.
If fp is NULL, fflush delivers pending output from all
open files.
Additionally, if fp is a seekable input stream visiting a file descriptor, set the position of the file descriptor to match next unread byte, useful for obeying POSIX semantics when ending a process without consuming all input from the stream.
fflush_unlocked is a non-thread-safe version of fflush.
fflush_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fflush_unlocked is equivalent to fflush.
The alternate functions _fflush_r and _fflush_unlocked_r are
reentrant versions, where the extra argument reent is a pointer to
a reentrancy structure, and fp must not be NULL.
Returns
fflush returns 0 unless it encounters a write error; in that
situation, it returns EOF.
Portability
ANSI C requires fflush. The behavior on input streams is only
specified by POSIX, and not all implementations follow POSIX rules.
fflush_unlocked is a BSD extension also provided by GNU libc.
No supporting OS subroutines are required.
Next: fgetpos—record position in a stream or file, Previous: fflush, fflush_unlocked—flush buffered file output, Up: Input and Output (stdio.h) [Contents][Index]
fgetc, fgetc_unlocked—get a character from a file or streamSynopsis
#include <stdio.h> int fgetc(FILE *fp); #define _BSD_SOURCE #include <stdio.h> int fgetc_unlocked(FILE *fp); #include <stdio.h> int _fgetc_r(struct _reent *ptr, FILE *fp); #define _BSD_SOURCE #include <stdio.h> int _fgetc_unlocked_r(struct _reent *ptr, FILE *fp);
Description
Use fgetc to get the next single character from the file or stream
identified by fp. As a side effect, fgetc advances the file’s
current position indicator.
For a macro version of this function, see getc.
fgetc_unlocked is a non-thread-safe version of fgetc.
fgetc_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fgetc_unlocked is equivalent to fgetc.
The functions _fgetc_r and _fgetc_unlocked_r are simply reentrant
versions that are passed the additional reentrant structure pointer
argument: ptr.
Returns
The next character (read as an unsigned char, and cast to
int), unless there is no more data, or the host system reports a
read error; in either of these situations, fgetc returns EOF.
You can distinguish the two situations that cause an EOF result by
using the ferror and feof functions.
Portability
ANSI C requires fgetc.
fgetc_unlocked is a BSD extension also provided by GNU libc.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: fgets, fgets_unlocked—get character string from a file or stream, Previous: fgetc, fgetc_unlocked—get a character from a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
fgetpos—record position in a stream or fileSynopsis
#include <stdio.h> int fgetpos(FILE *restrict fp, fpos_t *restrict pos); int _fgetpos_r(struct _reent *ptr, FILE *restrict fp, fpos_t *restrict pos);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
You can use fgetpos to report on the current position for a file
identified by fp; fgetpos will write a value
representing that position at *pos. Later, you can
use this value with fsetpos to return the file to this
position.
In the current implementation, fgetpos simply uses a character
count to represent the file position; this is the same number that
would be returned by ftell.
Returns
fgetpos returns 0 when successful. If fgetpos fails, the
result is 1. Failure occurs on streams that do not support
positioning; the global errno indicates this condition with the
value ESPIPE.
Portability
fgetpos is required by the ANSI C standard, but the meaning of the
value it records is not specified beyond requiring that it be
acceptable as an argument to fsetpos. In particular, other
conforming C implementations may return a different result from
ftell than what fgetpos writes at *pos.
No supporting OS subroutines are required.
Next: fgetwc, getwc, fgetwc_unlocked, getwc_unlocked—get a wide character from a file or stream, Previous: fgetpos—record position in a stream or file, Up: Input and Output (stdio.h) [Contents][Index]
fgets, fgets_unlocked—get character string from a file or streamSynopsis
#include <stdio.h> char *fgets(char *restrict buf, int n, FILE *restrict fp); #define _GNU_SOURCE #include <stdio.h> char *fgets_unlocked(char *restrict buf, int n, FILE *restrict fp); #include <stdio.h> char *_fgets_r(struct _reent *ptr, char *restrict buf, int n, FILE *restrict fp); #include <stdio.h> char *_fgets_unlocked_r(struct _reent *ptr, char *restrict buf, int n, FILE *restrict fp);
Description
Reads at most n-1 characters from fp until a newline
is found. The characters including to the newline are stored
in buf. The buffer is terminated with a 0.
fgets_unlocked is a non-thread-safe version of fgets.
fgets_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fgets_unlocked is equivalent to fgets.
The functions _fgets_r and _fgets_unlocked_r are simply
reentrant versions that are passed the additional reentrant structure
pointer argument: ptr.
Returns
fgets returns the buffer passed to it, with the data
filled in. If end of file occurs with some data already
accumulated, the data is returned with no other indication. If
no data are read, NULL is returned instead.
Portability
fgets should replace all uses of gets. Note however
that fgets returns all of the data, while gets removes
the trailing newline (with no indication that it has done so.)
fgets_unlocked is a GNU extension.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: fgetws, fgetws_unlocked—get wide character string from a file or stream, Previous: fgets, fgets_unlocked—get character string from a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
fgetwc, getwc, fgetwc_unlocked, getwc_unlocked—get a wide character from a file or streamSynopsis
#include <stdio.h> #include <wchar.h> wint_t fgetwc(FILE *fp); #define _GNU_SOURCE #include <stdio.h> #include <wchar.h> wint_t fgetwc_unlocked(FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _fgetwc_r(struct _reent *ptr, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _fgetwc_unlocked_r(struct _reent *ptr, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t getwc(FILE *fp); #define _GNU_SOURCE #include <stdio.h> #include <wchar.h> wint_t getwc_unlocked(FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _getwc_r(struct _reent *ptr, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _getwc_unlocked_r(struct _reent *ptr, FILE *fp);
Description
Use fgetwc to get the next wide character from the file or stream
identified by fp. As a side effect, fgetwc advances the file’s
current position indicator.
fgetwc_unlocked is a non-thread-safe version of fgetwc.
fgetwc_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fgetwc_unlocked is equivalent to fgetwc.
The getwc and getwc_unlocked functions or macros functions identically
to fgetwc and fgetwc_unlocked. It may be implemented as a macro, and
may evaluate its argument more than once. There is no reason ever to use it.
_fgetwc_r, _getwc_r, _fgetwc_unlocked_r, and _getwc_unlocked_r
are simply reentrant versions of the above functions that are passed the
additional reentrant structure pointer argument: ptr.
Returns
The next wide character cast to wint_t, unless there is no more data,
or the host system reports a read error; in either of these situations,
fgetwc and getwc return WEOF.
You can distinguish the two situations that cause an EOF result by
using the ferror and feof functions.
Portability
fgetwc and getwc are required by C99 and POSIX.1-2001.
fgetwc_unlocked and getwc_unlocked are GNU extensions.
Next: fileno, fileno_unlocked—return file descriptor associated with stream, Previous: fgetwc, getwc, fgetwc_unlocked, getwc_unlocked—get a wide character from a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
fgetws, fgetws_unlocked—get wide character string from a file or streamSynopsis
#include <wchar.h>
wchar_t *fgetws(wchar_t *__restrict ws, int n,
FILE *__restrict fp);
#define _GNU_SOURCE
#include <wchar.h>
wchar_t *fgetws_unlocked(wchar_t *__restrict ws, int n,
FILE *__restrict fp);
#include <wchar.h>
wchar_t *_fgetws_r(struct _reent *ptr, wchar_t *ws,
int n, FILE *fp);
#include <wchar.h>
wchar_t *_fgetws_unlocked_r(struct _reent *ptr, wchar_t *ws,
int n, FILE *fp);
Description
Reads at most n-1 wide characters from fp until a newline
is found. The wide characters including to the newline are stored
in ws. The buffer is terminated with a 0.
fgetws_unlocked is a non-thread-safe version of fgetws.
fgetws_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fgetws_unlocked is equivalent to fgetws.
The _fgetws_r and _fgetws_unlocked_r functions are simply reentrant
version of the above and are passed an additional reentrancy structure
pointer: ptr.
Returns
fgetws returns the buffer passed to it, with the data
filled in. If end of file occurs with some data already
accumulated, the data is returned with no other indication. If
no data are read, NULL is returned instead.
Portability
fgetws is required by C99 and POSIX.1-2001.
fgetws_unlocked is a GNU extension.
Next: fmemopen—open a stream around a fixed-length string, Previous: fgetws, fgetws_unlocked—get wide character string from a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
fileno, fileno_unlocked—return file descriptor associated with streamSynopsis
#include <stdio.h> int fileno(FILE *fp); #define _BSD_SOURCE #include <stdio.h> int fileno_unlocked(FILE *fp);
Description
You can use fileno to return the file descriptor identified by fp.
fileno_unlocked is a non-thread-safe version of fileno.
fileno_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fileno_unlocked is equivalent to fileno.
Returns
fileno returns a non-negative integer when successful.
If fp is not an open stream, fileno returns -1.
Portability
fileno is not part of ANSI C.
POSIX requires fileno.
fileno_unlocked is a BSD extension also provided by GNU libc.
Supporting OS subroutines required: none.
Next: fopen—open a file, Previous: fileno, fileno_unlocked—return file descriptor associated with stream, Up: Input and Output (stdio.h) [Contents][Index]
fmemopen—open a stream around a fixed-length stringSynopsis
#include <stdio.h>
FILE *fmemopen(void *restrict buf, size_t size,
const char *restrict mode);
Description
fmemopen creates a seekable FILE stream that wraps a
fixed-length buffer of size bytes starting at buf. The stream
is opened with mode treated as in fopen, where append mode
starts writing at the first NUL byte. If buf is NULL, then
size bytes are automatically provided as if by malloc, with
the initial size of 0, and mode must contain + so that data
can be read after it is written.
The stream maintains a current position, which moves according to
bytes read or written, and which can be one past the end of the array.
The stream also maintains a current file size, which is never greater
than size. If mode starts with r, the position starts at
0, and file size starts at size if buf was provided. If
mode starts with w, the position and file size start at 0,
and if buf was provided, the first byte is set to NUL. If
mode starts with a, the position and file size start at the
location of the first NUL byte, or else size if buf was
provided.
When reading, NUL bytes have no significance, and reads cannot exceed
the current file size. When writing, the file size can increase up to
size as needed, and NUL bytes may be embedded in the stream (see
open_memstream for an alternative that automatically enlarges the
buffer). When the stream is flushed or closed after a write that
changed the file size, a NUL byte is written at the current position
if there is still room; if the stream is not also open for reading, a
NUL byte is additionally written at the last byte of buf when the
stream has exceeded size, so that a write-only buf is always
NUL-terminated when the stream is flushed or closed (and the initial
size should take this into account). It is not possible to seek
outside the bounds of size. A NUL byte written during a flush is
restored to its previous value when seeking elsewhere in the string.
Returns
The return value is an open FILE pointer on success. On error,
NULL is returned, and errno will be set to EINVAL if size
is zero or mode is invalid, ENOMEM if buf was NULL and memory
could not be allocated, or EMFILE if too many streams are already
open.
Portability
This function is being added to POSIX 200x, but is not in POSIX 2001.
Supporting OS subroutines required: sbrk.
Next: fopencookie—open a stream with custom callbacks, Previous: fmemopen—open a stream around a fixed-length string, Up: Input and Output (stdio.h) [Contents][Index]
fopen—open a fileSynopsis
#include <stdio.h>
FILE *fopen(const char *file, const char *mode);
FILE *_fopen_r(struct _reent *reent,
const char *file, const char *mode);
Description
fopen initializes the data structures needed to read or write a
file. Specify the file’s name as the string at file, and the kind
of access you need to the file with the string at mode.
The alternate function _fopen_r is a reentrant version.
The extra argument reent is a pointer to a reentrancy structure.
Three fundamental kinds of access are available: read, write, and append.
*mode must begin with one of the three characters ‘r’,
‘w’, or ‘a’, to select one of these:
rOpen the file for reading; the operation will fail if the file does not exist, or if the host system does not permit you to read it.
wOpen the file for writing from the beginning of the file: effectively, this always creates a new file. If the file whose name you specified already existed, its old contents are discarded.
aOpen the file for appending data, that is writing from the end of
file. When you open a file this way, all data always goes to the
current end of file; you cannot change this using fseek.
Some host systems distinguish between “binary” and “text” files.
Such systems may perform data transformations on data written to, or
read from, files opened as “text”.
If your system is one of these, then you can append a ‘b’ to any
of the three modes above, to specify that you are opening the file as
a binary file (the default is to open the file as a text file).
‘rb’, then, means “read binary”; ‘wb’, “write binary”; and
‘ab’, “append binary”.
To make C programs more portable, the ‘b’ is accepted on all
systems, whether or not it makes a difference.
Finally, you might need to both read and write from the same file.
You can also append a ‘+’ to any of the three modes, to permit
this. (If you want to append both ‘b’ and ‘+’, you can do it
in either order: for example, "rb+" means the same thing as
"r+b" when used as a mode string.)
Use "r+" (or "rb+") to permit reading and writing anywhere in
an existing file, without discarding any data; "w+" (or "wb+")
to create a new file (or begin by discarding all data from an old one)
that permits reading and writing anywhere in it; and "a+" (or
"ab+") to permit reading anywhere in an existing file, but writing
only at the end.
Returns
fopen returns a file pointer which you can use for other file
operations, unless the file you requested could not be opened; in that
situation, the result is NULL. If the reason for failure was an
invalid string at mode, errno is set to EINVAL.
Portability
fopen is required by ANSI C.
Supporting OS subroutines required: close, fstat, isatty,
lseek, open, read, sbrk, write.
Next: fpurge—discard pending file I/O, Previous: fopen—open a file, Up: Input and Output (stdio.h) [Contents][Index]
fopencookie—open a stream with custom callbacksSynopsis
#include <stdio.h>
FILE *fopencookie(const void *cookie, const char *mode,
cookie_io_functions_t functions);
Description
fopencookie creates a FILE stream where I/O is performed using
custom callbacks. The callbacks are registered via the structure:
typedef ssize_t (*cookie_read_function_t)(void *_cookie, char *_buf, size_t _n); typedef ssize_t (*cookie_write_function_t)(void *_cookie, const char *_buf, size_t _n); typedef int (*cookie_seek_function_t)(void *_cookie, off_t *_off, int _whence); typedef int (*cookie_close_function_t)(void *_cookie);
typedef struct
{
cookie_read_function_t *read;
cookie_write_function_t *write;
cookie_seek_function_t *seek;
cookie_close_function_t *close;
} cookie_io_functions_t;
The stream is opened with mode treated as in fopen. The
callbacks functions.read and functions.write may only be NULL
when mode does not require them.
functions.read should return -1 on failure, or else the number of
bytes read (0 on EOF). It is similar to read, except that
cookie will be passed as the first argument.
functions.write should return -1 on failure, or else the number of
bytes written. It is similar to write, except that cookie
will be passed as the first argument.
functions.seek should return -1 on failure, and 0 on success, with
_off set to the current file position. It is a cross between
lseek and fseek, with the _whence argument interpreted in
the same manner. A NULL functions.seek makes the stream behave
similarly to a pipe in relation to stdio functions that require
positioning.
functions.close should return -1 on failure, or 0 on success. It
is similar to close, except that cookie will be passed as the
first argument. A NULL functions.close merely flushes all data
then lets fclose succeed. A failed close will still invalidate
the stream.
Read and write I/O functions are allowed to change the underlying
buffer on fully buffered or line buffered streams by calling
setvbuf. They are also not required to completely fill or empty
the buffer. They are not, however, allowed to change streams from
unbuffered to buffered or to change the state of the line buffering
flag. They must also be prepared to have read or write calls occur on
buffers other than the one most recently specified.
Returns
The return value is an open FILE pointer on success. On error,
NULL is returned, and errno will be set to EINVAL if a
function pointer is missing or mode is invalid, ENOMEM if the
stream cannot be created, or EMFILE if too many streams are already
open.
Portability
This function is a newlib extension, copying the prototype from Linux.
It is not portable. See also the funopen interface from BSD.
Supporting OS subroutines required: sbrk.
Next: fputc, fputc_unlocked—write a character on a stream or file, Previous: fopencookie—open a stream with custom callbacks, Up: Input and Output (stdio.h) [Contents][Index]
fpurge—discard pending file I/OSynopsis
#include <stdio.h> int fpurge(FILE *fp); int _fpurge_r(struct _reent *reent, FILE *fp); #include <stdio.h> #include <stdio_ext.h> void __fpurge(FILE *fp);
Description
Use fpurge to clear all buffers of the given stream. For output
streams, this discards data not yet written to disk. For input streams,
this discards any data from ungetc and any data retrieved from disk
but not yet read via getc. This is more severe than fflush,
and generally is only needed when manually altering the underlying file
descriptor of a stream.
__fpurge behaves exactly like fpurge but does not return a value.
The alternate function _fpurge_r is a reentrant version, where the
extra argument reent is a pointer to a reentrancy structure, and
fp must not be NULL.
Returns
fpurge returns 0 unless fp is not valid, in which case it
returns EOF and sets errno.
Portability
These functions are not portable to any standard.
No supporting OS subroutines are required.
Next: fputs, fputs_unlocked—write a character string in a file or stream, Previous: fpurge—discard pending file I/O, Up: Input and Output (stdio.h) [Contents][Index]
fputc, fputc_unlocked—write a character on a stream or fileSynopsis
#include <stdio.h> int fputc(int ch, FILE *fp); #define _BSD_SOURCE #include <stdio.h> int fputc_unlocked(int ch, FILE *fp); #include <stdio.h> int _fputc_r(struct _rent *ptr, int ch, FILE *fp); #include <stdio.h> int _fputc_unlocked_r(struct _rent *ptr, int ch, FILE *fp);
Description
fputc converts the argument ch from an int to an
unsigned char, then writes it to the file or stream identified by
fp.
If the file was opened with append mode (or if the stream cannot support positioning), then the new character goes at the end of the file or stream. Otherwise, the new character is written at the current value of the position indicator, and the position indicator oadvances by one.
For a macro version of this function, see putc.
fputc_unlocked is a non-thread-safe version of fputc.
fputc_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fputc_unlocked is equivalent to fputc.
The _fputc_r and _fputc_unlocked_r functions are simply reentrant
versions of the above that take an additional reentrant structure
argument: ptr.
Returns
If successful, fputc returns its argument ch. If an error
intervenes, the result is EOF. You can use ‘ferror(fp)’ to
query for errors.
Portability
fputc is required by ANSI C.
fputc_unlocked is a BSD extension also provided by GNU libc.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: fputwc, putwc, fputwc_unlocked, putwc_unlocked—write a wide character on a stream or file, Previous: fputc, fputc_unlocked—write a character on a stream or file, Up: Input and Output (stdio.h) [Contents][Index]
fputs, fputs_unlocked—write a character string in a file or streamSynopsis
#include <stdio.h> int fputs(const char *restrict s, FILE *restrict fp); #define _GNU_SOURCE #include <stdio.h> int fputs_unlocked(const char *restrict s, FILE *restrict fp); #include <stdio.h> int _fputs_r(struct _reent *ptr, const char *restrict s, FILE *restrict fp); #include <stdio.h> int _fputs_unlocked_r(struct _reent *ptr, const char *restrict s, FILE *restrict fp);
Description
fputs writes the string at s (but without the trailing null)
to the file or stream identified by fp.
fputs_unlocked is a non-thread-safe version of fputs.
fputs_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fputs_unlocked is equivalent to fputs.
_fputs_r and _fputs_unlocked_r are simply reentrant versions of the
above that take an additional reentrant struct pointer argument: ptr.
Returns
If successful, the result is 0; otherwise, the result is EOF.
Portability
ANSI C requires fputs, but does not specify that the result on
success must be 0; any non-negative value is permitted.
fputs_unlocked is a GNU extension.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: fputws, fputws_unlocked—write a wide character string in a file or stream, Previous: fputs, fputs_unlocked—write a character string in a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
fputwc, putwc, fputwc_unlocked, putwc_unlocked—write a wide character on a stream or fileSynopsis
#include <stdio.h> #include <wchar.h> wint_t fputwc(wchar_t wc, FILE *fp); #define _GNU_SOURCE #include <stdio.h> #include <wchar.h> wint_t fputwc_unlocked(wchar_t wc, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _fputwc_r(struct _reent *ptr, wchar_t wc, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _fputwc_unlocked_r(struct _reent *ptr, wchar_t wc, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t putwc(wchar_t wc, FILE *fp); #define _GNU_SOURCE #include <stdio.h> #include <wchar.h> wint_t putwc_unlocked(wchar_t wc, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _putwc_r(struct _reent *ptr, wchar_t wc, FILE *fp); #include <stdio.h> #include <wchar.h> wint_t _putwc_unlocked_r(struct _reent *ptr, wchar_t wc, FILE *fp);
Description
fputwc writes the wide character argument wc to the file or
stream identified by fp.
If the file was opened with append mode (or if the stream cannot support positioning), then the new wide character goes at the end of the file or stream. Otherwise, the new wide character is written at the current value of the position indicator, and the position indicator oadvances by one.
fputwc_unlocked is a non-thread-safe version of fputwc.
fputwc_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fputwc_unlocked is equivalent to fputwc.
The putwc and putwc_unlocked functions or macros function identically
to fputwc and fputwc_unlocked. They may be implemented as a macro, and
may evaluate its argument more than once. There is no reason ever to use them.
The _fputwc_r, _putwc_r, _fputwc_unlocked_r, and
_putwc_unlocked_r functions are simply reentrant versions of the above
that take an additional reentrant structure argument: ptr.
Returns
If successful, fputwc and putwc return their argument wc.
If an error intervenes, the result is EOF. You can use
‘ferror(fp)’ to query for errors.
Portability
fputwc and putwc are required by C99 and POSIX.1-2001.
fputwc_unlocked and putwc_unlocked are GNU extensions.
Next: fread, fread_unlocked—read array elements from a file, Previous: fputwc, putwc, fputwc_unlocked, putwc_unlocked—write a wide character on a stream or file, Up: Input and Output (stdio.h) [Contents][Index]
fputws, fputws_unlocked—write a wide character string in a file or streamSynopsis
#include <wchar.h>
int fputws(const wchar_t *__restrict ws, FILE *__restrict fp);
#define _GNU_SOURCE
#include <wchar.h>
int fputws_unlocked(const wchar_t *__restrict ws, FILE *__restrict fp);
#include <wchar.h>
int _fputws_r(struct _reent *ptr, const wchar_t *ws,
FILE *fp);
#include <wchar.h>
int _fputws_unlocked_r(struct _reent *ptr, const wchar_t *ws,
FILE *fp);
Description
fputws writes the wide character string at ws (but without the
trailing null) to the file or stream identified by fp.
fputws_unlocked is a non-thread-safe version of fputws.
fputws_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fputws_unlocked is equivalent to fputws.
_fputws_r and _fputws_unlocked_r are simply reentrant versions of the
above that take an additional reentrant struct pointer argument: ptr.
Returns
If successful, the result is a non-negative integer; otherwise, the result
is -1 to indicate an error.
Portability
fputws is required by C99 and POSIX.1-2001.
fputws_unlocked is a GNU extension.
Next: freopen—open a file using an existing file descriptor, Previous: fputws, fputws_unlocked—write a wide character string in a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
fread, fread_unlocked—read array elements from a fileSynopsis
#include <stdio.h>
size_t fread(void *restrict buf, size_t size, size_t count,
FILE *restrict fp);
#define _BSD_SOURCE
#include <stdio.h>
size_t fread_unlocked(void *restrict buf, size_t size, size_t count,
FILE *restrict fp);
#include <stdio.h>
size_t _fread_r(struct _reent *ptr, void *restrict buf,
size_t size, size_t count, FILE *restrict fp);
#include <stdio.h>
size_t _fread_unlocked_r(struct _reent *ptr, void *restrict buf,
size_t size, size_t count, FILE *restrict fp);
Description
fread attempts to copy, from the file or stream identified by
fp, count elements (each of size size) into memory,
starting at buf. fread may copy fewer elements than
count if an error, or end of file, intervenes.
fread also advances the file position indicator (if any) for
fp by the number of characters actually read.
fread_unlocked is a non-thread-safe version of fread.
fread_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fread_unlocked is equivalent to fread.
_fread_r and _fread_unlocked_r are simply reentrant versions of the
above that take an additional reentrant structure pointer argument: ptr.
Returns
The result of fread is the number of elements it succeeded in
reading.
Portability
ANSI C requires fread.
fread_unlocked is a BSD extension also provided by GNU libc.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: fseek, fseeko—set file position, Previous: fread, fread_unlocked—read array elements from a file, Up: Input and Output (stdio.h) [Contents][Index]
freopen—open a file using an existing file descriptorSynopsis
#include <stdio.h>
FILE *freopen(const char *restrict file, const char *restrict mode,
FILE *restrict fp);
FILE *_freopen_r(struct _reent *ptr, const char *restrict file,
const char *restrict mode, FILE *restrict fp);
Description
Use this variant of fopen if you wish to specify a particular file
descriptor fp (notably stdin, stdout, or stderr) for
the file.
If fp was associated with another file or stream, freopen
closes that other file or stream (but ignores any errors while closing
it).
file and mode are used just as in fopen.
If file is NULL, the underlying stream is modified rather than
closed. The file cannot be given a more permissive access mode (for
example, a mode of "w" will fail on a read-only file descriptor),
but can change status such as append or binary mode. If modification
is not possible, failure occurs.
Returns
If successful, the result is the same as the argument fp. If the
file cannot be opened as specified, the result is NULL.
Portability
ANSI C requires freopen.
Supporting OS subroutines required: close, fstat, isatty,
lseek, open, read, sbrk, write.
Next: __fsetlocking—set or query locking mode on FILE stream, Previous: freopen—open a file using an existing file descriptor, Up: Input and Output (stdio.h) [Contents][Index]
fseek, fseeko—set file positionSynopsis
#include <stdio.h>
int fseek(FILE *fp, long offset, int whence);
int fseeko(FILE *fp, off_t offset, int whence);
int _fseek_r(struct _reent *ptr, FILE *fp,
long offset, int whence);
int _fseeko_r(struct _reent *ptr, FILE *fp,
off_t offset, int whence);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
You can use fseek/fseeko to set the position for the file identified by
fp. The value of offset determines the new position, in one
of three ways selected by the value of whence (defined as macros
in ‘stdio.h’):
SEEK_SET—offset is the absolute file position (an offset
from the beginning of the file) desired. offset must be positive.
SEEK_CUR—offset is relative to the current file position.
offset can meaningfully be either positive or negative.
SEEK_END—offset is relative to the current end of file.
offset can meaningfully be either positive (to increase the size
of the file) or negative.
See ftell/ftello to determine the current file position.
Returns
fseek/fseeko return 0 when successful. On failure, the
result is EOF. The reason for failure is indicated in errno:
either ESPIPE (the stream identified by fp doesn’t support
repositioning) or EINVAL (invalid file position).
Portability
ANSI C requires fseek.
fseeko is defined by the Single Unix specification.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: fsetpos—restore position of a stream or file, Previous: fseek, fseeko—set file position, Up: Input and Output (stdio.h) [Contents][Index]
__fsetlocking—set or query locking mode on FILE streamSynopsis
#include <stdio.h> #include <stdio_ext.h> int __fsetlocking(FILE *fp, int type);
Description
This function sets how the stdio functions handle locking of FILE fp.
The following values describe type:
FSETLOCKING_INTERNAL is the default state, where stdio functions
automatically lock and unlock the stream.
FSETLOCKING_BYCALLER means that automatic locking in stdio functions
is disabled. Applications which set this take all responsibility for file
locking themselves.
FSETLOCKING_QUERY returns the current locking mode without changing it.
Returns
__fsetlocking returns the current locking mode of fp.
Portability
This function originates from Solaris and is also provided by GNU libc.
No supporting OS subroutines are required.
Next: ftell, ftello—return position in a stream or file, Previous: __fsetlocking—set or query locking mode on FILE stream, Up: Input and Output (stdio.h) [Contents][Index]
fsetpos—restore position of a stream or fileSynopsis
#include <stdio.h>
int fsetpos(FILE *fp, const fpos_t *pos);
int _fsetpos_r(struct _reent *ptr, FILE *fp,
const fpos_t *pos);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
You can use fsetpos to return the file identified by fp to a previous
position *pos (after first recording it with fgetpos).
See fseek for a similar facility.
Returns
fgetpos returns 0 when successful. If fgetpos fails, the
result is 1. The reason for failure is indicated in errno:
either ESPIPE (the stream identified by fp doesn’t support
repositioning) or EINVAL (invalid file position).
Portability
ANSI C requires fsetpos, but does not specify the nature of
*pos beyond identifying it as written by fgetpos.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: funopen, fropen, fwopen—open a stream with custom callbacks, Previous: fsetpos—restore position of a stream or file, Up: Input and Output (stdio.h) [Contents][Index]
ftell, ftello—return position in a stream or fileSynopsis
#include <stdio.h> long ftell(FILE *fp); off_t ftello(FILE *fp); long _ftell_r(struct _reent *ptr, FILE *fp); off_t _ftello_r(struct _reent *ptr, FILE *fp);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
The result of ftell/ftello is the current position for a file
identified by fp. If you record this result, you can later
use it with fseek/fseeko to return the file to this
position. The difference between ftell and ftello is that
ftell returns long and ftello returns off_t.
In the current implementation, ftell/ftello simply uses a character
count to represent the file position; this is the same number that
would be recorded by fgetpos.
Returns
ftell/ftello return the file position, if possible. If they cannot do
this, they return -1L. Failure occurs on streams that do not support
positioning; the global errno indicates this condition with the
value ESPIPE.
Portability
ftell is required by the ANSI C standard, but the meaning of its
result (when successful) is not specified beyond requiring that it be
acceptable as an argument to fseek. In particular, other
conforming C implementations may return a different result from
ftell than what fgetpos records.
ftello is defined by the Single Unix specification.
No supporting OS subroutines are required.
Next: fwide—set and determine the orientation of a FILE stream, Previous: ftell, ftello—return position in a stream or file, Up: Input and Output (stdio.h) [Contents][Index]
funopen, fropen, fwopen—open a stream with custom callbacksSynopsis
#include <stdio.h>
FILE *funopen(const void *cookie,
int (*readfn) (void *cookie, char *buf, int n),
int (*writefn) (void *cookie, const char *buf, int n),
fpos_t (*seekfn) (void *cookie, fpos_t off, int whence),
int (*closefn) (void *cookie));
FILE *fropen(const void *cookie,
int (*readfn) (void *cookie, char *buf, int n));
FILE *fwopen(const void *cookie,
int (*writefn) (void *cookie, const char *buf, int n));
Description
funopen creates a FILE stream where I/O is performed using
custom callbacks. At least one of readfn and writefn must be
provided, which determines whether the stream behaves with mode <"r">,
<"w">, or <"r+">.
readfn should return -1 on failure, or else the number of bytes
read (0 on EOF). It is similar to read, except that <int> rather
than <size_t> bounds a transaction size, and cookie will be passed
as the first argument. A NULL readfn makes attempts to read the
stream fail.
writefn should return -1 on failure, or else the number of bytes
written. It is similar to write, except that <int> rather than
<size_t> bounds a transaction size, and cookie will be passed as
the first argument. A NULL writefn makes attempts to write the
stream fail.
seekfn should return (fpos_t)-1 on failure, or else the current
file position. It is similar to lseek, except that cookie
will be passed as the first argument. A NULL seekfn makes the
stream behave similarly to a pipe in relation to stdio functions that
require positioning. This implementation assumes fpos_t and off_t are
the same type.
closefn should return -1 on failure, or 0 on success. It is
similar to close, except that cookie will be passed as the
first argument. A NULL closefn merely flushes all data then lets
fclose succeed. A failed close will still invalidate the stream.
Read and write I/O functions are allowed to change the underlying
buffer on fully buffered or line buffered streams by calling
setvbuf. They are also not required to completely fill or empty
the buffer. They are not, however, allowed to change streams from
unbuffered to buffered or to change the state of the line buffering
flag. They must also be prepared to have read or write calls occur on
buffers other than the one most recently specified.
The functions fropen and fwopen are convenience macros around
funopen that only use the specified callback.
Returns
The return value is an open FILE pointer on success. On error,
NULL is returned, and errno will be set to EINVAL if a
function pointer is missing, ENOMEM if the stream cannot be created,
or EMFILE if too many streams are already open.
Portability
This function is a newlib extension, copying the prototype from BSD.
It is not portable. See also the fopencookie interface from Linux.
Supporting OS subroutines required: sbrk.
Next: fwrite, fwrite_unlocked—write array elements, Previous: funopen, fropen, fwopen—open a stream with custom callbacks, Up: Input and Output (stdio.h) [Contents][Index]
fwide—set and determine the orientation of a FILE streamSynopsis
#include <wchar.h> int fwide(FILE *fp, int mode); int _fwide_r(struct _reent *ptr, FILE *fp, int mode);
Description
When mode is zero, the fwide function determines the current
orientation of fp. It returns a value > 0 if fp is
wide-character oriented, i.e. if wide character I/O is permitted but
char I/O is disallowed. It returns a value < 0 if fp is byte
oriented, i.e. if char I/O is permitted but wide character I/O is
disallowed. It returns zero if fp has no orientation yet; in
this case the next I/O operation might change the orientation (to byte
oriented if it is a char I/O operation, or to wide-character oriented
if it is a wide character I/O operation).
Once a stream has an orientation, it cannot be changed and persists until the stream is closed, unless the stream is re-opened with freopen, which removes the orientation of the stream.
When mode is non-zero, the fwide function first attempts to set
fp’s orientation (to wide-character oriented if mode > 0, or to
byte oriented if mode < 0). It then returns a value denoting the
current orientation, as above.
Returns
The fwide function returns fp’s orientation, after possibly
changing it. A return value > 0 means wide-character oriented. A return
value < 0 means byte oriented. A return value of zero means undecided.
Portability
C99, POSIX.1-2001.
Next: getc—read a character (macro), Previous: fwide—set and determine the orientation of a FILE stream, Up: Input and Output (stdio.h) [Contents][Index]
fwrite, fwrite_unlocked—write array elementsSynopsis
#include <stdio.h>
size_t fwrite(const void *restrict buf, size_t size,
size_t count, FILE *restrict fp);
#define _BSD_SOURCE
#include <stdio.h>
size_t fwrite_unlocked(const void *restrict buf, size_t size,
size_t count, FILE *restrict fp);
#include <stdio.h>
size_t _fwrite_r(struct _reent *ptr, const void *restrict buf, size_t size,
size_t count, FILE *restrict fp);
#include <stdio.h>
size_t _fwrite_unlocked_r(struct _reent *ptr, const void *restrict buf, size_t size,
size_t count, FILE *restrict fp);
Description
fwrite attempts to copy, starting from the memory location
buf, count elements (each of size size) into the file or
stream identified by fp. fwrite may copy fewer elements than
count if an error intervenes.
fwrite also advances the file position indicator (if any) for
fp by the number of characters actually written.
fwrite_unlocked is a non-thread-safe version of fwrite.
fwrite_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fwrite_unlocked is equivalent to fwrite.
_fwrite_r and _fwrite_unlocked_r are simply reentrant versions of the
above that take an additional reentrant structure argument: ptr.
Returns
If fwrite succeeds in writing all the elements you specify, the
result is the same as the argument count. In any event, the
result is the number of complete elements that fwrite copied to
the file.
Portability
ANSI C requires fwrite.
fwrite_unlocked is a BSD extension also provided by GNU libc.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: getc_unlocked—non-thread-safe version of getc (macro), Previous: fwrite, fwrite_unlocked—write array elements, Up: Input and Output (stdio.h) [Contents][Index]
getc—read a character (macro)Synopsis
#include <stdio.h> int getc(FILE *fp); #include <stdio.h> int _getc_r(struct _reent *ptr, FILE *fp);
Description
getc is a macro, defined in stdio.h. You can use getc
to get the next single character from the file or stream
identified by fp. As a side effect, getc advances the file’s
current position indicator.
For a subroutine version of this macro, see fgetc.
The _getc_r function is simply the reentrant version of getc
which passes an additional reentrancy structure pointer argument: ptr.
Returns
The next character (read as an unsigned char, and cast to
int), unless there is no more data, or the host system reports a
read error; in either of these situations, getc returns EOF.
You can distinguish the two situations that cause an EOF result by
using the ferror and feof functions.
Portability
ANSI C requires getc; it suggests, but does not require, that
getc be implemented as a macro. The standard explicitly permits
macro implementations of getc to use the argument more than once;
therefore, in a portable program, you should not use an expression
with side effects as the getc argument.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: getchar—read a character (macro), Previous: getc—read a character (macro), Up: Input and Output (stdio.h) [Contents][Index]
getc_unlocked—non-thread-safe version of getc (macro)Synopsis
#include <stdio.h> int getc_unlocked(FILE *fp); #include <stdio.h> int _getc_unlocked_r(FILE *fp);
Description
getc_unlocked is a non-thread-safe version of getc declared in
stdio.h. getc_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). These
functions may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the ( FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
getc_unlocked is equivalent to getc.
The _getc_unlocked_r function is simply the reentrant version of
get_unlocked which passes an additional reentrancy structure pointer
argument: ptr.
Returns
See getc.
Portability
POSIX 1003.1 requires getc_unlocked. getc_unlocked may be
implemented as a macro, so arguments should not have side-effects.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: getchar_unlocked—non-thread-safe version of getchar (macro), Previous: getc_unlocked—non-thread-safe version of getc (macro), Up: Input and Output (stdio.h) [Contents][Index]
getchar—read a character (macro)Synopsis
#include <stdio.h> int getchar(void); int _getchar_r(struct _reent *reent);
Description
getchar is a macro, defined in stdio.h. You can use getchar
to get the next single character from the standard input stream.
As a side effect, getchar advances the standard input’s
current position indicator.
The alternate function _getchar_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
The next character (read as an unsigned char, and cast to
int), unless there is no more data, or the host system reports a
read error; in either of these situations, getchar returns EOF.
You can distinguish the two situations that cause an EOF result by
using ‘ferror(stdin)’ and ‘feof(stdin)’.
Portability
ANSI C requires getchar; it suggests, but does not require, that
getchar be implemented as a macro.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: getdelim—read a line up to a specified line delimiter, Previous: getchar—read a character (macro), Up: Input and Output (stdio.h) [Contents][Index]
getchar_unlocked—non-thread-safe version of getchar (macro)Synopsis
#include <stdio.h> int getchar_unlocked(void); #include <stdio.h> int _getchar_unlocked_r(struct _reent *ptr);
Description
getchar_unlocked is a non-thread-safe version of getchar
declared in stdio.h. getchar_unlocked may only safely be used
within a scope protected by flockfile() (or ftrylockfile()) and
funlockfile(). These functions may safely be used in a multi-threaded
program if and only if they are called while the invoking thread owns
the ( FILE *) object, as is the case after a successful call to the
flockfile() or ftrylockfile() functions. If threads are disabled,
then getchar_unlocked is equivalent to getchar.
The _getchar_unlocked_r function is simply the reentrant version of
getchar_unlocked which passes an addtional reentrancy structure pointer
argument: ptr.
Returns
See getchar.
Portability
POSIX 1003.1 requires getchar_unlocked. getchar_unlocked may
be implemented as a macro.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: getline—read a line from a file, Previous: getchar_unlocked—non-thread-safe version of getchar (macro), Up: Input and Output (stdio.h) [Contents][Index]
getdelim—read a line up to a specified line delimiterSynopsis
#include <stdio.h>
int getdelim(char **bufptr, size_t *n,
int delim, FILE *fp);
Description
getdelim reads a file fp up to and possibly including a specified
delimiter delim. The line is read into a buffer pointed to
by bufptr and designated with size *n. If the buffer is
not large enough, it will be dynamically grown by getdelim.
As the buffer is grown, the pointer to the size n will be
updated.
Returns
getdelim returns -1 if no characters were successfully read;
otherwise, it returns the number of bytes successfully read.
At end of file, the result is nonzero.
Portability
getdelim is a glibc extension.
No supporting OS subroutines are directly required.
Next: gets—get character string (obsolete, use fgets instead), Previous: getdelim—read a line up to a specified line delimiter, Up: Input and Output (stdio.h) [Contents][Index]
getline—read a line from a fileSynopsis
#include <stdio.h> ssize_t getline(char **bufptr, size_t *n, FILE *fp);
Description
getline reads a file fp up to and possibly including the
newline character. The line is read into a buffer pointed to
by bufptr and designated with size *n. If the buffer is
not large enough, it will be dynamically grown by getdelim.
As the buffer is grown, the pointer to the size n will be
updated.
getline is equivalent to getdelim(bufptr, n, ’\n’, fp);
Returns
getline returns -1 if no characters were successfully read,
otherwise, it returns the number of bytes successfully read.
at end of file, the result is nonzero.
Portability
getline is a glibc extension.
No supporting OS subroutines are directly required.
Next: getw—read a word (int), Previous: getline—read a line from a file, Up: Input and Output (stdio.h) [Contents][Index]
gets—get character string (obsolete, use fgets instead)Synopsis
#include <stdio.h> char *gets(char *buf); char *_gets_r(struct _reent *reent, char *buf);
Description
Reads characters from standard input until a newline is found.
The characters up to the newline are stored in buf. The
newline is discarded, and the buffer is terminated with a 0.
This is a dangerous function, as it has no way of checking the amount of space available in buf. One of the attacks used by the Internet Worm of 1988 used this to overrun a buffer allocated on the stack of the finger daemon and overwrite the return address, causing the daemon to execute code downloaded into it over the connection.
The alternate function _gets_r is a reentrant version. The extra
argument reent is a pointer to a reentrancy structure.
Returns
gets returns the buffer passed to it, with the data filled
in. If end of file occurs with some data already accumulated,
the data is returned with no other indication. If end of file
occurs with no data in the buffer, NULL is returned.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: getwchar, getwchar_unlocked—read a wide character from standard input, Previous: gets—get character string (obsolete, use fgets instead), Up: Input and Output (stdio.h) [Contents][Index]
getw—read a word (int)Synopsis
#include <stdio.h> int getw(FILE *fp);
Description
getw is a function, defined in stdio.h. You can use getw
to get the next word from the file or stream identified by fp. As
a side effect, getw advances the file’s current position
indicator.
Returns
The next word (read as an int), unless there is no more
data or the host system reports a read error; in either of these
situations, getw returns EOF. Since EOF is a valid
int, you must use ferror or feof to distinguish these
situations.
Portability
getw is a remnant of K&R C; it is not part of any ISO C Standard.
fread should be used instead. In fact, this implementation of
getw is based upon fread.
Supporting OS subroutines required: fread.
Next: mktemp, mkstemp, mkostemp, mkstemps,, Previous: getw—read a word (int), Up: Input and Output (stdio.h) [Contents][Index]
getwchar, getwchar_unlocked—read a wide character from standard inputSynopsis
#include <wchar.h> wint_t getwchar(void); #define _GNU_SOURCE #include <wchar.h> wint_t getwchar_unlocked(void); #include <wchar.h> wint_t _getwchar_r(struct _reent *reent); #include <wchar.h> wint_t _getwchar_unlocked_r(struct _reent *reent);
Description
getwchar function or macro is the wide character equivalent of
the getchar function. You can use getwchar to get the next
wide character from the standard input stream. As a side effect,
getwchar advances the standard input’s current position indicator.
getwchar_unlocked is a non-thread-safe version of getwchar.
getwchar_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
getwchar_unlocked is equivalent to getwchar.
The alternate functions _getwchar_r and _getwchar_unlocked_r are
reentrant versions of the above. The extra argument reent is a pointer to
a reentrancy structure.
Returns
The next wide character cast to wint_t, unless there is no more
data, or the host system reports a read error; in either of these
situations, getwchar returns WEOF.
You can distinguish the two situations that cause an WEOF result by
using ‘ferror(stdin)’ and ‘feof(stdin)’.
Portability
getwchar is required by C99.
getwchar_unlocked is a GNU extension.
Next: open_memstream, open_wmemstream—open a write stream around an arbitrary-length string, Previous: getwchar, getwchar_unlocked—read a wide character from standard input, Up: Input and Output (stdio.h) [Contents][Index]
mktemp, mkstemp, mkostemp, mkstemps,Synopsis
#include <stdlib.h>
char *mktemp(char *path);
char *mkdtemp(char *path);
int mkstemp(char *path);
int mkstemps(char *path, int suffixlen);
int mkostemp(char *path, int flags);
int mkostemps(char *path, int suffixlen, int flags);
char *_mktemp_r(struct _reent *reent, char *path);
char *_mkdtemp_r(struct _reent *reent, char *path);
int *_mkstemp_r(struct _reent *reent, char *path);
int *_mkstemps_r(struct _reent *reent, char *path, int len);
int *_mkostemp_r(struct _reent *reent, char *path,
int flags);
int *_mkostemps_r(struct _reent *reent, char *path, int len,
int flags);
Description
mktemp, mkstemp, and mkstemps attempt to generate a file name
that is not yet in use for any existing file. mkstemp and mkstemps
create the file and open it for reading and writing; mktemp simply
generates the file name (making mktemp a security risk). mkostemp
and mkostemps allow the addition of other open flags, such
as O_CLOEXEC, O_APPEND, or O_SYNC. On platforms with a
separate text mode, mkstemp forces O_BINARY, while mkostemp
allows the choice between O_BINARY, O_TEXT, or 0 for default.
mkdtemp attempts to create a directory instead of a file, with a
permissions mask of 0700.
You supply a simple pattern for the generated file name, as the string
at path. The pattern should be a valid filename (including path
information if you wish) ending with at least six ‘X’
characters. The generated filename will match the leading part of the
name you supply, with the trailing ‘X’ characters replaced by some
combination of digits and letters. With mkstemps, the ‘X’
characters end suffixlen bytes before the end of the string.
The alternate functions _mktemp_r, _mkdtemp_r, _mkstemp_r,
_mkostemp_r, _mkostemps_r, and _mkstemps_r are reentrant
versions. The extra argument reent is a pointer to a reentrancy
structure.
Returns
mktemp returns the pointer path to the modified string
representing an unused filename, unless it could not generate one, or
the pattern you provided is not suitable for a filename; in that case,
it returns NULL. Be aware that there is an inherent race between
generating the name and attempting to create a file by that name;
you are advised to use O_EXCL|O_CREAT.
mkdtemp returns the pointer path to the modified string if the
directory was created, otherwise it returns NULL.
mkstemp, mkstemps, mkostemp, and mkostemps return a file
descriptor to the newly created file, unless it could not generate an
unused filename, or the pattern you provided is not suitable for a
filename; in that case, it returns -1.
Notes
Never use mktemp. The generated filenames are easy to guess and
there’s a race between the test if the file exists and the creation
of the file. In combination this makes mktemp prone to attacks
and using it is a security risk. Whenever possible use mkstemp
instead. It doesn’t suffer the race condition.
Portability
ANSI C does not require either mktemp or mkstemp; the System
V Interface Definition requires mktemp as of Issue 2. POSIX 2001
requires mkstemp, and POSIX 2008 requires mkdtemp while
deprecating mktemp. mkstemps, mkostemp, and mkostemps
are not standardized.
Supporting OS subroutines required: getpid, mkdir, open, stat.
Next: perror—print an error message on standard error, Previous: mktemp, mkstemp, mkostemp, mkstemps,, Up: Input and Output (stdio.h) [Contents][Index]
open_memstream, open_wmemstream—open a write stream around an arbitrary-length stringSynopsis
#include <stdio.h>
FILE *open_memstream(char **restrict buf,
size_t *restrict size);
#include <wchar.h>
FILE *open_wmemstream(wchar_t **restrict buf,
size_t *restrict size);
Description
open_memstream creates a seekable, byte-oriented FILE stream that
wraps an arbitrary-length buffer, created as if by malloc. The current
contents of *buf are ignored; this implementation uses *size
as a hint of the maximum size expected, but does not fail if the hint
was wrong. The parameters buf and size are later stored
through following any call to fflush or fclose, set to the
current address and usable size of the allocated string; although
after fflush, the pointer is only valid until another stream operation
that results in a write. Behavior is undefined if the user alters
either *buf or *size prior to fclose.
open_wmemstream is like open_memstream just with the associated
stream being wide-oriented. The size set in size in subsequent
operations is the number of wide characters.
The stream is write-only, since the user can directly read *buf
after a flush; see fmemopen for a way to wrap a string with a
readable stream. The user is responsible for calling free on
the final *buf after fclose.
Any time the stream is flushed, a NUL byte is written at the current
position (but is not counted in the buffer length), so that the string
is always NUL-terminated after at most *size bytes (or wide characters
in case of open_wmemstream). However, data previously written beyond
the current stream offset is not lost, and the NUL value written during a
flush is restored to its previous value when seeking elsewhere in the string.
Returns
The return value is an open FILE pointer on success. On error,
NULL is returned, and errno will be set to EINVAL if buf
or size is NULL, ENOMEM if memory could not be allocated, or
EMFILE if too many streams are already open.
Portability
POSIX.1-2008
Supporting OS subroutines required: sbrk.
Next: putc—write a character (macro), Previous: open_memstream, open_wmemstream—open a write stream around an arbitrary-length string, Up: Input and Output (stdio.h) [Contents][Index]
perror—print an error message on standard errorSynopsis
#include <stdio.h> void perror(char *prefix); void _perror_r(struct _reent *reent, char *prefix);
Description
Use perror to print (on standard error) an error message
corresponding to the current value of the global variable errno.
Unless you use NULL as the value of the argument prefix, the
error message will begin with the string at prefix, followed by a
colon and a space (: ). The remainder of the error message is one
of the strings described for strerror.
The alternate function _perror_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
perror returns no result.
Portability
ANSI C requires perror, but the strings issued vary from one
implementation to another.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
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putc—write a character (macro)Synopsis
#include <stdio.h> int putc(int ch, FILE *fp); #include <stdio.h> int _putc_r(struct _reent *ptr, int ch, FILE *fp);
Description
putc is a macro, defined in stdio.h. putc
writes the argument ch to the file or stream identified by
fp, after converting it from an int to an unsigned char.
If the file was opened with append mode (or if the stream cannot support positioning), then the new character goes at the end of the file or stream. Otherwise, the new character is written at the current value of the position indicator, and the position indicator advances by one.
For a subroutine version of this macro, see fputc.
The _putc_r function is simply the reentrant version of
putc that takes an additional reentrant structure argument: ptr.
Returns
If successful, putc returns its argument ch. If an error
intervenes, the result is EOF. You can use ‘ferror(fp)’ to
query for errors.
Portability
ANSI C requires putc; it suggests, but does not require, that
putc be implemented as a macro. The standard explicitly permits
macro implementations of putc to use the fp argument more than once;
therefore, in a portable program, you should not use an expression
with side effects as this argument.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: putchar—write a character (macro), Previous: putc—write a character (macro), Up: Input and Output (stdio.h) [Contents][Index]
putc_unlocked—non-thread-safe version of putc (macro)Synopsis
#include <stdio.h> int putc_unlocked(int ch, FILE *fp); #include <stdio.h> int _putc_unlocked_r(struct _reent *ptr, int ch, FILE *fp);
Description
putc_unlocked is a non-thread-safe version of putc declared in
stdio.h. putc_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). These
functions may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the ( FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
putc_unlocked is equivalent to putc.
The function _putc_unlocked_r is simply the reentrant version of
putc_unlocked that takes an additional reentrant structure pointer
argument: ptr.
Returns
See putc.
Portability
POSIX 1003.1 requires putc_unlocked. putc_unlocked may be
implemented as a macro, so arguments should not have side-effects.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: putchar_unlocked—non-thread-safe version of putchar (macro), Previous: putc_unlocked—non-thread-safe version of putc (macro), Up: Input and Output (stdio.h) [Contents][Index]
putchar—write a character (macro)Synopsis
#include <stdio.h> int putchar(int ch); int _putchar_r(struct _reent *reent, int ch);
Description
putchar is a macro, defined in stdio.h. putchar
writes its argument to the standard output stream,
after converting it from an int to an unsigned char.
The alternate function _putchar_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
If successful, putchar returns its argument ch. If an error
intervenes, the result is EOF. You can use ‘ferror(stdin)’ to
query for errors.
Portability
ANSI C requires putchar; it suggests, but does not require, that
putchar be implemented as a macro.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: puts—write a character string, Previous: putchar—write a character (macro), Up: Input and Output (stdio.h) [Contents][Index]
putchar_unlocked—non-thread-safe version of putchar (macro)Synopsis
#include <stdio.h> int putchar_unlocked(int ch);
Description
putchar_unlocked is a non-thread-safe version of putchar
declared in stdio.h. putchar_unlocked may only safely be used
within a scope protected by flockfile() (or ftrylockfile()) and
funlockfile(). These functions may safely be used in a multi-threaded
program if and only if they are called while the invoking thread owns
the ( FILE *) object, as is the case after a successful call to the
flockfile() or ftrylockfile() functions. If threads are disabled,
then putchar_unlocked is equivalent to putchar.
Returns
See putchar.
Portability
POSIX 1003.1 requires putchar_unlocked. putchar_unlocked may
be implemented as a macro.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: putw—write a word (int), Previous: putchar_unlocked—non-thread-safe version of putchar (macro), Up: Input and Output (stdio.h) [Contents][Index]
puts—write a character stringSynopsis
#include <stdio.h> int puts(const char *s); int _puts_r(struct _reent *reent, const char *s);
Description
puts writes the string at s (followed by a newline, instead of
the trailing null) to the standard output stream.
The alternate function _puts_r is a reentrant version. The extra
argument reent is a pointer to a reentrancy structure.
Returns
If successful, the result is a nonnegative integer; otherwise, the
result is EOF.
Portability
ANSI C requires puts, but does not specify that the result on
success must be 0; any non-negative value is permitted.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: putwchar, putwchar_unlocked—write a wide character to standard output, Previous: puts—write a character string, Up: Input and Output (stdio.h) [Contents][Index]
putw—write a word (int)Synopsis
#include <stdio.h> int putw(int w, FILE *fp);
Description
putw is a function, defined in stdio.h. You can use putw
to write a word to the file or stream identified by fp. As a side
effect, putw advances the file’s current position indicator.
Returns
Zero on success, EOF on failure.
Portability
putw is a remnant of K&R C; it is not part of any ISO C Standard.
fwrite should be used instead. In fact, this implementation of
putw is based upon fwrite.
Supporting OS subroutines required: fwrite.
Next: remove—delete a file’s name, Previous: putw—write a word (int), Up: Input and Output (stdio.h) [Contents][Index]
putwchar, putwchar_unlocked—write a wide character to standard outputSynopsis
#include <wchar.h> wint_t putwchar(wchar_t wc); #include <wchar.h> wint_t putwchar_unlocked(wchar_t wc); #include <wchar.h> wint_t _putwchar_r(struct _reent *reent, wchar_t wc); #include <wchar.h> wint_t _putwchar_unlocked_r(struct _reent *reent, wchar_t wc);
Description
The putwchar function or macro is the wide-character equivalent of
the putchar function. It writes the wide character wc to stdout.
putwchar_unlocked is a non-thread-safe version of putwchar.
putwchar_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
putwchar_unlocked is equivalent to putwchar.
The alternate functions _putwchar_r and _putwchar_unlocked_r are
reentrant versions of the above. The extra argument reent is a pointer
to a reentrancy structure.
Returns
If successful, putwchar returns its argument wc. If an error
intervenes, the result is EOF. You can use ‘ferror(stdin)’ to
query for errors.
Portability
putwchar is required by C99.
putwchar_unlocked is a GNU extension.
Next: rename—rename a file, Previous: putwchar, putwchar_unlocked—write a wide character to standard output, Up: Input and Output (stdio.h) [Contents][Index]
remove—delete a file’s nameSynopsis
#include <stdio.h> int remove(char *filename); int _remove_r(struct _reent *reent, char *filename);
Description
Use remove to dissolve the association between a particular
filename (the string at filename) and the file it represents.
After calling remove with a particular filename, you will no
longer be able to open the file by that name.
In this implementation, you may use remove on an open file without
error; existing file descriptors for the file will continue to access
the file’s data until the program using them closes the file.
The alternate function _remove_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
remove returns 0 if it succeeds, -1 if it fails.
Portability
ANSI C requires remove, but only specifies that the result on
failure be nonzero. The behavior of remove when you call it on an
open file may vary among implementations.
Supporting OS subroutine required: unlink.
Next: rewind—reinitialize a file or stream, Previous: remove—delete a file’s name, Up: Input and Output (stdio.h) [Contents][Index]
rename—rename a fileSynopsis
#include <stdio.h> int rename(const char *old, const char *new);
Description
Use rename to establish a new name (the string at new) for a
file now known by the string at old. After a successful
rename, the file is no longer accessible by the string at old.
If rename fails, the file named *old is unaffected. The
conditions for failure depend on the host operating system.
Returns
The result is either 0 (when successful) or -1 (when the file
could not be renamed).
Portability
ANSI C requires rename, but only specifies that the result on
failure be nonzero. The effects of using the name of an existing file
as *new may vary from one implementation to another.
Supporting OS subroutines required: link, unlink, or rename.
Next: setbuf—specify full buffering for a file or stream, Previous: rename—rename a file, Up: Input and Output (stdio.h) [Contents][Index]
rewind—reinitialize a file or streamSynopsis
#include <stdio.h> void rewind(FILE *fp); void _rewind_r(struct _reent *ptr, FILE *fp);
Description
rewind returns the file position indicator (if any) for the file
or stream identified by fp to the beginning of the file. It also
clears any error indicator and flushes any pending output.
Returns
rewind does not return a result.
Portability
ANSI C requires rewind.
No supporting OS subroutines are required.
Next: setbuffer—specify full buffering for a file or stream with size, Previous: rewind—reinitialize a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
setbuf—specify full buffering for a file or streamSynopsis
#include <stdio.h> void setbuf(FILE *fp, char *buf);
Description
setbuf specifies that output to the file or stream identified by fp
should be fully buffered. All output for this file will go to a
buffer (of size BUFSIZ, specified in ‘stdio.h’). Output will
be passed on to the host system only when the buffer is full, or when
an input operation intervenes.
You may, if you wish, supply your own buffer by passing a pointer to
it as the argument buf. It must have size BUFSIZ. You can
also use NULL as the value of buf, to signal that the
setbuf function is to allocate the buffer.
Warnings
You may only use setbuf before performing any file operation other
than opening the file.
If you supply a non-null buf, you must ensure that the associated storage continues to be available until you close the stream identified by fp.
Returns
setbuf does not return a result.
Portability
Both ANSI C and the System V Interface Definition (Issue 2) require
setbuf. However, they differ on the meaning of a NULL buffer
pointer: the SVID issue 2 specification says that a NULL buffer
pointer requests unbuffered output. For maximum portability, avoid
NULL buffer pointers.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: setlinebuf—specify line buffering for a file or stream, Previous: setbuf—specify full buffering for a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
setbuffer—specify full buffering for a file or stream with sizeSynopsis
#include <stdio.h> void setbuffer(FILE *fp, char *buf, int size);
Description
setbuffer specifies that output to the file or stream identified by
fp should be fully buffered. All output for this file will go to a
buffer (of size size). Output will be passed on to the host system
only when the buffer is full, or when an input operation intervenes.
You may, if you wish, supply your own buffer by passing a pointer to
it as the argument buf. It must have size size. You can
also use NULL as the value of buf, to signal that the
setbuffer function is to allocate the buffer.
Warnings
You may only use setbuffer before performing any file operation
other than opening the file.
If you supply a non-null buf, you must ensure that the associated storage continues to be available until you close the stream identified by fp.
Returns
setbuffer does not return a result.
Portability
This function comes from BSD not ANSI or POSIX.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: setvbuf—specify file or stream buffering, Previous: setbuffer—specify full buffering for a file or stream with size, Up: Input and Output (stdio.h) [Contents][Index]
setlinebuf—specify line buffering for a file or streamSynopsis
#include <stdio.h> void setlinebuf(FILE *fp);
Description
setlinebuf specifies that output to the file or stream identified by
fp should be line buffered. This causes the file or stream to pass
on output to the host system at every newline, as well as when the
buffer is full, or when an input operation intervenes.
Warnings
You may only use setlinebuf before performing any file operation
other than opening the file.
Returns
setlinebuf returns as per setvbuf.
Portability
This function comes from BSD not ANSI or POSIX.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: siprintf, fiprintf, iprintf, sniprintf, asiprintf, asniprintf—format output (integer only), Previous: setlinebuf—specify line buffering for a file or stream, Up: Input and Output (stdio.h) [Contents][Index]
setvbuf—specify file or stream bufferingSynopsis
#include <stdio.h>
int setvbuf(FILE *fp, char *buf,
int mode, size_t size);
Description
Use setvbuf to specify what kind of buffering you want for the
file or stream identified by fp, by using one of the following
values (from stdio.h) as the mode argument:
_IONBFDo not use a buffer: send output directly to the host system for the file or stream identified by fp.
_IOFBFUse full output buffering: output will be passed on to the host system only when the buffer is full, or when an input operation intervenes.
_IOLBFUse line buffering: pass on output to the host system at every newline, as well as when the buffer is full, or when an input operation intervenes.
Use the size argument to specify how large a buffer you wish. You
can supply the buffer itself, if you wish, by passing a pointer to a
suitable area of memory as buf. Otherwise, you may pass NULL
as the buf argument, and setvbuf will allocate the buffer.
Warnings
You may only use setvbuf before performing any file operation other
than opening the file.
If you supply a non-null buf, you must ensure that the associated storage continues to be available until you close the stream identified by fp.
Returns
A 0 result indicates success, EOF failure (invalid mode or
size can cause failure).
Portability
Both ANSI C and the System V Interface Definition (Issue 2) require
setvbuf. However, they differ on the meaning of a NULL buffer
pointer: the SVID issue 2 specification says that a NULL buffer
pointer requests unbuffered output. For maximum portability, avoid
NULL buffer pointers.
Both specifications describe the result on failure only as a nonzero value.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: siscanf, fiscanf, iscanf—scan and format non-floating input, Previous: setvbuf—specify file or stream buffering, Up: Input and Output (stdio.h) [Contents][Index]
siprintf, fiprintf, iprintf, sniprintf, asiprintf, asniprintf—format output (integer only)Synopsis
#include <stdio.h>
int iprintf(const char *format, ...);
int fiprintf(FILE *fd, const char *format , ...);
int siprintf(char *str, const char *format, ...);
int sniprintf(char *str, size_t size, const char *format,
...);
int asiprintf(char **strp, const char *format, ...);
char *asniprintf(char *str, size_t *size,
const char *format, ...);
int _iprintf_r(struct _reent *ptr, const char *format, ...);
int _fiprintf_r(struct _reent *ptr, FILE *fd,
const char *format, ...);
int _siprintf_r(struct _reent *ptr, char *str,
const char *format, ...);
int _sniprintf_r(struct _reent *ptr, char *str, size_t size,
const char *format, ...);
int _asiprintf_r(struct _reent *ptr, char **strp,
const char *format, ...);
char *_asniprintf_r(struct _reent *ptr, char *str,
size_t *size, const char *format, ...);
Description
iprintf, fiprintf, siprintf, sniprintf,
asiprintf, and asniprintf are the same as printf,
fprintf, sprintf, snprintf, asprintf, and
asnprintf, respectively, except that they restrict usage
to non-floating-point format specifiers.
_iprintf_r, _fiprintf_r, _asiprintf_r,
_siprintf_r, _sniprintf_r, _asniprintf_r are
simply reentrant versions of the functions above.
Returns
Similar to printf, fprintf, sprintf, snprintf, asprintf,
and asnprintf.
Portability
iprintf, fiprintf, siprintf, sniprintf, asiprintf,
and asniprintf are newlib extensions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: sprintf, fprintf, printf, snprintf, asprintf, asnprintf—format output, Previous: siprintf, fiprintf, iprintf, sniprintf, asiprintf, asniprintf—format output (integer only), Up: Input and Output (stdio.h) [Contents][Index]
siscanf, fiscanf, iscanf—scan and format non-floating inputSynopsis
#include <stdio.h>
int iscanf(const char *format, ...);
int fiscanf(FILE *fd, const char *format, ...);
int siscanf(const char *str, const char *format, ...);
int _iscanf_r(struct _reent *ptr, const char *format, ...);
int _fiscanf_r(struct _reent *ptr, FILE *fd,
const char *format, ...);
int _siscanf_r(struct _reent *ptr, const char *str,
const char *format, ...);
Description
iscanf, fiscanf, and siscanf are the same as
scanf, fscanf, and sscanf respectively, only that
they restrict the available formats to non-floating-point
format specifiers.
The routines _iscanf_r, _fiscanf_r, and _siscanf_r are reentrant
versions of iscanf, fiscanf, and siscanf that take an additional
first argument pointing to a reentrancy structure.
Returns
iscanf returns the number of input fields successfully
scanned, converted and stored; the return value does
not include scanned fields which were not stored.
If iscanf attempts to read at end-of-file, the return
value is EOF.
If no fields were stored, the return value is 0.
Portability
iscanf, fiscanf, and siscanf are newlib extensions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: sscanf, fscanf, scanf—scan and format input, Previous: siscanf, fiscanf, iscanf—scan and format non-floating input, Up: Input and Output (stdio.h) [Contents][Index]
sprintf, fprintf, printf, snprintf, asprintf, asnprintf—format outputSynopsis
#include <stdio.h>
int printf(const char *restrict format, ...);
int fprintf(FILE *restrict fd, const char *restrict format, ...);
int sprintf(char *restrict str, const char *restrict format, ...);
int snprintf(char *restrict str, size_t size, const char *restrict format,
...);
int asprintf(char **restrict strp, const char *restrict format, ...);
char *asnprintf(char *restrict str, size_t *restrict size, const char *restrict format,
...);
int _printf_r(struct _reent *ptr, const char *restrict format, ...);
int _fprintf_r(struct _reent *ptr, FILE *restrict fd,
const char *restrict format, ...);
int _sprintf_r(struct _reent *ptr, char *restrict str,
const char *restrict format, ...);
int _snprintf_r(struct _reent *ptr, char *restrict str, size_t size,
const char *restrict format, ...);
int _asprintf_r(struct _reent *ptr, char **restrict strp,
const char *restrict format, ...);
char *_asnprintf_r(struct _reent *ptr, char *restrict str,
size_t *restrict size, const char *restrict format, ...);
Description
printf accepts a series of arguments, applies to each a
format specifier from *format, and writes the
formatted data to stdout, without a terminating NUL
character. The behavior of printf is undefined if there
are not enough arguments for the format. printf returns
when it reaches the end of the format string. If there are
more arguments than the format requires, excess arguments are
ignored.
fprintf is like printf, except that output is directed
to the stream fd rather than stdout.
sprintf is like printf, except that output is directed
to the buffer str, and a terminating NUL is output.
Behavior is undefined if more output is generated than the
buffer can hold.
snprintf is like sprintf, except that output is
limited to at most size bytes, including the terminating
NUL. As a special case, if size is 0, str can be
NULL, and snprintf merely calculates how many bytes would
be printed.
asprintf is like sprintf, except that the output is
stored in a dynamically allocated buffer, pstr, which
should be freed later with free.
asnprintf is like sprintf, except that the return type
is either the original str if it was large enough, or a
dynamically allocated string if the output exceeds *size;
the length of the result is returned in *size. When
dynamic allocation occurs, the contents of the original
str may have been modified.
For sprintf, snprintf, and asnprintf, the behavior
is undefined if the output *str overlaps with one of
the arguments. Behavior is also undefined if the argument for
%n within *format overlaps another argument.
format is a pointer to a character string containing two
types of objects: ordinary characters (other than %),
which are copied unchanged to the output, and conversion
specifications, each of which is introduced by %. (To
include % in the output, use %% in the format string.)
A conversion specification has the following form:
%[pos][flags][width][.prec][size]type
The fields of the conversion specification have the following meanings:
Conversions normally consume arguments in the order that they
are presented. However, it is possible to consume arguments
out of order, and reuse an argument for more than one
conversion specification (although the behavior is undefined
if the same argument is requested with different types), by
specifying pos, which is a decimal integer followed by
’$’. The integer must be between 1 and <NL_ARGMAX> from
limits.h, and if argument %n$ is requested, all earlier
arguments must be requested somewhere within format. If
positional parameters are used, then all conversion
specifications except for %% must specify a position.
This positional parameters method is a POSIX extension to the C
standard definition for the functions.
flags is an optional sequence of characters which control
output justification, numeric signs, decimal points, trailing
zeros, and octal and hex prefixes. The flag characters are
minus (-), plus (+), space ( ), zero (0), sharp
(#), and quote ('). They can appear in any
combination, although not all flags can be used for all
conversion specification types.
'A POSIX extension to the C standard. However, this
implementation presently treats it as a no-op, which
is the default behavior for the C locale, anyway. (If
it did what it is supposed to, when type were i,
d, u, f, F, g, or G, the
integer portion of the conversion would be formatted
with thousands’ grouping wide characters.)
-The result of the conversion is left justified, and the right is padded with blanks. If you do not use this flag, the result is right justified, and padded on the left.
+The result of a signed conversion (as
determined by type of d, i, a,
A, e, E, f, F, g, or
G) will always begin with a plus or minus
sign. (If you do not use this flag, positive
values do not begin with a plus sign.)
" " (space)If the first character of a signed conversion
specification is not a sign, or if a signed
conversion results in no characters, the
result will begin with a space. If the space
( ) flag and the plus (+) flag both
appear, the space flag is ignored.
0If the type character is d, i,
o, u, x, X, a, A,
e, E, f, F, g, or G: leading
zeros are used to pad the field width
(following any indication of sign or base); no
spaces are used for padding. If the zero
(0) and minus (-) flags both appear,
the zero (0) flag will be ignored. For
d, i, o, u, x, and X
conversions, if a precision prec is
specified, the zero (0) flag is ignored.
Note that 0 is interpreted as a flag, not
as the beginning of a field width.
#The result is to be converted to an alternative form, according to the type character.
The alternative form output with the # flag depends on the type character:
oIncreases precision to force the first digit of the result to be a zero.
xA non-zero result will have a 0x
prefix.
XA non-zero result will have a 0X
prefix.
a, A, e, E, f, or FThe result will always contain a decimal point even if no digits follow the point. (Normally, a decimal point appears only if a digit follows it.) Trailing zeros are removed.
g or GThe result will always contain a decimal point even if no digits follow the point. Trailing zeros are not removed.
all othersUndefined.
width is an optional minimum field width. You can
either specify it directly as a decimal integer, or
indirectly by using instead an asterisk (*), in
which case an int argument is used as the field
width. If positional arguments are used, then the
width must also be specified positionally as *m$,
with m as a decimal integer. Negative field widths
are treated as specifying the minus (-) flag for
left justfication, along with a positive field width.
The resulting format may be wider than the specified
width.
prec is an optional field; if present, it is
introduced with ‘.’ (a period). You can specify
the precision either directly as a decimal integer or
indirectly by using an asterisk (*), in which case
an int argument is used as the precision. If
positional arguments are used, then the precision must
also be specified positionally as *m$, with m as a
decimal integer. Supplying a negative precision is
equivalent to omitting the precision. If only a
period is specified the precision is zero. The effect
depends on the conversion type.
d, i, o, u, x, or XMinimum number of digits to appear. If no precision is given, defaults to 1.
a or ANumber of digits to appear after the decimal point. If no precision is given, the precision defaults to the minimum needed for an exact representation.
e, E, f or FNumber of digits to appear after the decimal point. If no precision is given, the precision defaults to 6.
g or GMaximum number of significant digits. A precision of 0 is treated the same as a precision of 1. If no precision is given, the precision defaults to 6.
s or SMaximum number of characters to print from the string. If no precision is given, the entire string is printed.
all othersundefined.
size is an optional modifier that changes the data type that the corresponding argument has. Behavior is unspecified if a size is given that does not match the type.
hhWith d, i, o, u, x, or
X, specifies that the argument should be
converted to a signed char or unsigned
char before printing.
With n, specifies that the argument is a
pointer to a signed char.
hWith d, i, o, u, x, or
X, specifies that the argument should be
converted to a short or unsigned short
before printing.
With n, specifies that the argument is a
pointer to a short.
lWith d, i, o, u, x, or
X, specifies that the argument is a
long or unsigned long.
With c, specifies that the argument has
type wint_t.
With s, specifies that the argument is a
pointer to wchar_t.
With n, specifies that the argument is a
pointer to a long.
With a, A, e, E, f, F,
g, or G, has no effect (because of
vararg promotion rules, there is no need to
distinguish between float and double).
llWith d, i, o, u, x, or
X, specifies that the argument is a
long long or unsigned long long.
With n, specifies that the argument is a
pointer to a long long.
jWith d, i, o, u, x, or
X, specifies that the argument is an
intmax_t or uintmax_t.
With n, specifies that the argument is a
pointer to an intmax_t.
zWith d, i, o, u, x, or
X, specifies that the argument is a size_t.
With n, specifies that the argument is a
pointer to a size_t.
tWith d, i, o, u, x, or
X, specifies that the argument is a
ptrdiff_t.
With n, specifies that the argument is a
pointer to a ptrdiff_t.
LWith a, A, e, E, f, F,
g, or G, specifies that the argument
is a long double.
type specifies what kind of conversion printf
performs. Here is a table of these:
%Prints the percent character (%).
cPrints arg as single character. If the
l size specifier is in effect, a multibyte
character is printed.
CShort for %lc. A POSIX extension to the C standard.
sPrints the elements of a pointer to char
until the precision or a null character is
reached. If the l size specifier is in
effect, the pointer is to an array of
wchar_t, and the string is converted to
multibyte characters before printing.
SShort for %ls. A POSIX extension to the C standard.
d or iPrints a signed decimal integer; takes an
int. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
DNewlib extension, short for %ld.
oPrints an unsigned octal integer; takes an
unsigned. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
ONewlib extension, short for %lo.
uPrints an unsigned decimal integer; takes an
unsigned. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
UNewlib extension, short for %lu.
xPrints an unsigned hexadecimal integer (using
abcdef as digits beyond 9); takes an
unsigned. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
XLike x, but uses ABCDEF as digits
beyond 9.
fPrints a signed value of the form
[-]9999.9999, with the precision
determining how many digits follow the decimal
point; takes a double (remember that
float promotes to double as a vararg).
The low order digit is rounded to even. If
the precision results in at most DECIMAL_DIG
digits, the result is rounded correctly; if
more than DECIMAL_DIG digits are printed, the
result is only guaranteed to round back to the
original value.
If the value is infinite, the result is
inf, and no zero padding is performed. If
the value is not a number, the result is
nan, and no zero padding is performed.
FLike f, but uses INF and NAN for
non-finite numbers.
ePrints a signed value of the form
[-]9.9999e[+|-]999; takes a double.
The digit before the decimal point is non-zero
if the value is non-zero. The precision
determines how many digits appear between
. and e, and the exponent always
contains at least two digits. The value zero
has an exponent of zero. If the value is not
finite, it is printed like f.
ELike e, but using E to introduce the
exponent, and like F for non-finite
values.
gPrints a signed value in either f or e
form, based on the given value and
precision—an exponent less than -4 or
greater than the precision selects the e
form. Trailing zeros and the decimal point
are printed only if necessary; takes a
double.
GLike g, except use F or E form.
aPrints a signed value of the form
[-]0x1.ffffp[+|-]9; takes a double.
The letters abcdef are used for digits
beyond 9. The precision determines how
many digits appear after the decimal point.
The exponent contains at least one digit, and
is a decimal value representing the power of
2; a value of 0 has an exponent of 0.
Non-finite values are printed like f.
ALike a, except uses X, P, and
ABCDEF instead of lower case.
nTakes a pointer to int, and stores a count
of the number of bytes written so far. No
output is created.
pTakes a pointer to void, and prints it in
an implementation-defined format. This
implementation is similar to %#tx), except
that 0x appears even for the NULL pointer.
mPrints the output of strerror(errno); no
argument is required. A GNU extension.
_printf_r, _fprintf_r, _asprintf_r,
_sprintf_r, _snprintf_r, _asnprintf_r are simply
reentrant versions of the functions above.
Returns
On success, sprintf and asprintf return the number of bytes in
the output string, except the concluding NUL is not counted.
snprintf returns the number of bytes that would be in the output
string, except the concluding NUL is not counted. printf and
fprintf return the number of characters transmitted.
asnprintf returns the original str if there was enough room,
otherwise it returns an allocated string.
If an error occurs, the result of printf, fprintf,
snprintf, and asprintf is a negative value, and the result of
asnprintf is NULL. No error returns occur for sprintf. For
printf and fprintf, errno may be set according to
fputc. For asprintf and asnprintf, errno may be set
to ENOMEM if allocation fails, and for snprintf, errno may be
set to EOVERFLOW if size or the output length exceeds INT_MAX.
Bugs
The “”’ (quote) flag does not work when locale’s thousands_sep is not empty.
Portability
ANSI C requires printf, fprintf, sprintf, and
snprintf. asprintf and asnprintf are newlib extensions.
The ANSI C standard specifies that implementations must support at least formatted output of up to 509 characters. This implementation has no inherent limit.
Depending on how newlib was configured, not all format specifiers are supported.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: stdio_ext,__fbufsize,__fpending,__flbf,__freadable,__fwritable,__freading,__fwriting—access internals of FILE structure, Previous: sprintf, fprintf, printf, snprintf, asprintf, asnprintf—format output, Up: Input and Output (stdio.h) [Contents][Index]
sscanf, fscanf, scanf—scan and format inputSynopsis
#include <stdio.h>
int scanf(const char *restrict format, ...);
int fscanf(FILE *restrict fd, const char *restrict format, ...);
int sscanf(const char *restrict str, const char *restrict format, ...);
int _scanf_r(struct _reent *ptr, const char *restrict format, ...);
int _fscanf_r(struct _reent *ptr, FILE *restrict fd,
const char *restrict format, ...);
int _sscanf_r(struct _reent *ptr, const char *restrict str,
const char *restrict format, ...);
Description
scanf scans a series of input fields from standard input,
one character at a time. Each field is interpreted according to
a format specifier passed to scanf in the format string at
*format. scanf stores the interpreted input from
each field at the address passed to it as the corresponding argument
following format. You must supply the same number of
format specifiers and address arguments as there are input fields.
There must be sufficient address arguments for the given format specifiers; if not the results are unpredictable and likely disasterous. Excess address arguments are merely ignored.
scanf often produces unexpected results if the input diverges from
an expected pattern. Since the combination of gets or fgets
followed by sscanf is safe and easy, that is the preferred way
to be certain that a program is synchronized with input at the end
of a line.
fscanf and sscanf are identical to scanf, other than the
source of input: fscanf reads from a file, and sscanf
from a string.
The routines _scanf_r, _fscanf_r, and _sscanf_r are reentrant
versions of scanf, fscanf, and sscanf that take an additional
first argument pointing to a reentrancy structure.
The string at *format is a character sequence composed
of zero or more directives. Directives are composed of
one or more whitespace characters, non-whitespace characters,
and format specifications.
Whitespace characters are blank ( ), tab (\t), or
newline (\n).
When scanf encounters a whitespace character in the format string
it will read (but not store) all consecutive whitespace characters
up to the next non-whitespace character in the input.
Non-whitespace characters are all other ASCII characters except the
percent sign (%). When scanf encounters a non-whitespace
character in the format string it will read, but not store
a matching non-whitespace character.
Format specifications tell scanf to read and convert characters
from the input field into specific types of values, and store then
in the locations specified by the address arguments.
Trailing whitespace is left unread unless explicitly matched in the format string.
The format specifiers must begin with a percent sign (%)
and have the following form:
%[*][width][size]type
Each format specification begins with the percent character (%).
The other fields are:
an optional marker; if present, it suppresses interpretation and assignment of this input field.
an optional maximum field width: a decimal integer,
which controls the maximum number of characters that
will be read before converting the current input field. If the
input field has fewer than width characters, scanf
reads all the characters in the field, and then
proceeds with the next field and its format specification.
If a whitespace or a non-convertable character occurs
before width character are read, the characters up
to that character are read, converted, and stored.
Then scanf proceeds to the next format specification.
h, j, l, L, t, and z are optional size
characters which override the default way that scanf
interprets the data type of the corresponding argument.
| Modifier | Type(s) | |
|---|---|---|
| hh | d, i, o, u, x, n | convert input to char, store in char object |
| h | d, i, o, u, x, n | convert input to short, store in short object |
| h | D, I, O, U, X, e, f, c, s, p | no effect |
| j | d, i, o, u, x, n | convert input to intmax_t, store in intmax_t object |
| j | all others | no effect |
| l | d, i, o, u, x, n | convert input to long, store in long object |
| l | e, f, g | convert input to double, store in a double object |
| l | D, I, O, U, X, c, s, p | no effect |
| ll | d, i, o, u, x, n | convert to long long, store in long long object |
| L | d, i, o, u, x, n | convert to long long, store in long long object |
| L | e, f, g, E, G | convert to long double, store in long double object |
| L | all others | no effect |
| t | d, i, o, u, x, n | convert input to ptrdiff_t, store in ptrdiff_t object |
| t | all others | no effect |
| z | d, i, o, u, x, n | convert input to size_t, store in size_t object |
| z | all others | no effect |
A character to specify what kind of conversion
scanf performs. Here is a table of the conversion
characters:
%No conversion is done; the percent character (%) is stored.
cScans one character. Corresponding arg: (char *arg).
sReads a character string into the array supplied.
Corresponding arg: (char arg[]).
[pattern]Reads a non-empty character string into memory
starting at arg. This area must be large
enough to accept the sequence and a
terminating null character which will be added
automatically. (pattern is discussed in the paragraph following
this table). Corresponding arg: (char *arg).
dReads a decimal integer into the corresponding arg: (int *arg).
DReads a decimal integer into the corresponding
arg: (long *arg).
oReads an octal integer into the corresponding arg: (int *arg).
OReads an octal integer into the corresponding arg: (long *arg).
uReads an unsigned decimal integer into the corresponding
arg: (unsigned int *arg).
UReads an unsigned decimal integer into the corresponding arg:
(unsigned long *arg).
x,XRead a hexadecimal integer into the corresponding arg:
(int *arg).
e, f, gRead a floating-point number into the corresponding arg:
(float *arg).
E, F, GRead a floating-point number into the corresponding arg:
(double *arg).
iReads a decimal, octal or hexadecimal integer into the
corresponding arg: (int *arg).
IReads a decimal, octal or hexadecimal integer into the
corresponding arg: (long *arg).
nStores the number of characters read in the corresponding
arg: (int *arg).
pStores a scanned pointer. ANSI C leaves the details
to each implementation; this implementation treats
%p exactly the same as %U. Corresponding
arg: (void **arg).
A pattern of characters surrounded by square brackets can be used
instead of the s type character. pattern is a set of
characters which define a search set of possible characters making up
the scanf input field. If the first character in the brackets is a
caret (^), the search set is inverted to include all ASCII characters
except those between the brackets. There is also a range facility
which you can use as a shortcut. %[0-9] matches all decimal digits.
The hyphen must not be the first or last character in the set.
The character prior to the hyphen must be lexically less than the
character after it.
Here are some pattern examples:
%[abcd]matches strings containing only a, b, c, and d.
%[^abcd]matches strings containing any characters except a, b,
c, or d
%[A-DW-Z]matches strings containing A, B, C, D, W,
X, Y, Z
%[z-a]matches the characters z, -, and a
Floating point numbers (for field types e, f, g, E,
F, G) must correspond to the following general form:
[+/-] ddddd[.]ddd [E|e[+|-]ddd]
where objects inclosed in square brackets are optional, and ddd
represents decimal, octal, or hexadecimal digits.
Returns
scanf returns the number of input fields successfully
scanned, converted and stored; the return value does
not include scanned fields which were not stored.
If scanf attempts to read at end-of-file, the return
value is EOF.
If no fields were stored, the return value is 0.
scanf might stop scanning a particular field before
reaching the normal field end character, or may
terminate entirely.
scanf stops scanning and storing the current field
and moves to the next input field (if any)
in any of the following situations:
*) appears
after the % in the format specification; the current
input field is scanned but not stored.
Z is read when the format is decimal).
When scanf stops scanning the current input field for one of
these reasons, the next character is considered unread and
used as the first character of the following input field, or the
first character in a subsequent read operation on the input.
scanf will terminate under the following circumstances:
EOF.
When the format string contains a character sequence that is
not part of a format specification, the same character
sequence must appear in the input; scanf will
scan but not store the matched characters. If a
conflict occurs, the first conflicting character remains in the input
as if it had never been read.
Portability
scanf is ANSI C.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: swprintf, fwprintf, wprintf—wide character format output, Previous: sscanf, fscanf, scanf—scan and format input, Up: Input and Output (stdio.h) [Contents][Index]
stdio_ext,__fbufsize,__fpending,__flbf,__freadable,__fwritable,__freading,__fwriting—access internals of FILE structureSynopsis
#include <stdio.h> #include <stdio_ext.h> size_t __fbufsize(FILE *fp); size_t __fpending(FILE *fp); int __flbf(FILE *fp); int __freadable(FILE *fp); int __fwritable(FILE *fp); int __freading(FILE *fp); int __fwriting(FILE *fp);
Description
These functions provides access to the internals of the FILE structure fp.
Returns
__fbufsize returns the number of bytes in the buffer of stream fp.
__fpending returns the number of bytes in the output buffer of stream fp.
__flbf returns nonzero if stream fp is line-buffered, and 0 if not.
__freadable returns nonzero if stream fp may be read, and 0 if not.
__fwritable returns nonzero if stream fp may be written, and 0 if not.
__freading returns nonzero if stream fp if the last operation on
it was a read, or if it read-only, and 0 if not.
__fwriting returns nonzero if stream fp if the last operation on
it was a write, or if it write-only, and 0 if not.
Portability
These functions originate from Solaris and are also provided by GNU libc.
No supporting OS subroutines are required.
Next: swscanf, fwscanf, wscanf—scan and format wide character input, Previous: stdio_ext,__fbufsize,__fpending,__flbf,__freadable,__fwritable,__freading,__fwriting—access internals of FILE structure, Up: Input and Output (stdio.h) [Contents][Index]
swprintf, fwprintf, wprintf—wide character format outputSynopsis
#include <wchar.h>
int wprintf(const wchar_t *format, ...);
int fwprintf(FILE *__restrict fd,
const wchar_t *__restrict format, ...);
int swprintf(wchar_t *__restrict str, size_t size,
const wchar_t *__restrict format, ...);
int _wprintf_r(struct _reent *ptr, const wchar_t *format, ...);
int _fwprintf_r(struct _reent *ptr, FILE *fd,
const wchar_t *format, ...);
int _swprintf_r(struct _reent *ptr, wchar_t *str,
size_t size, const wchar_t *format, ...);
Description
wprintf accepts a series of arguments, applies to each a
format specifier from *format, and writes the
formatted data to stdout, without a terminating NUL
wide character. The behavior of wprintf is undefined if there
are not enough arguments for the format or if any argument is not the
right type for the corresponding conversion specifier. wprintf
returns when it reaches the end of the format string. If there are
more arguments than the format requires, excess arguments are
ignored.
fwprintf is like wprintf, except that output is directed
to the stream fd rather than stdout.
swprintf is like wprintf, except that output is directed
to the buffer str with a terminating wide NUL, and the
resulting string length is limited to at most size wide characters,
including the terminating NUL. It is considered an error if the
output (including the terminating wide-NULL) does not fit into
size wide characters. (This error behavior is not the same as for
snprintf, which swprintf is otherwise completely analogous to.
While snprintf allows the needed size to be known simply by giving
size=0, swprintf does not, giving an error instead.)
For swprintf the behavior is undefined if the output
*str overlaps with one of the arguments. Behavior is also
undefined if the argument for %n within *format
overlaps another argument.
format is a pointer to a wide character string containing two
types of objects: ordinary characters (other than %),
which are copied unchanged to the output, and conversion
specifications, each of which is introduced by %. (To
include % in the output, use %% in the format string.)
A conversion specification has the following form:
%[pos][flags][width][.prec][size]type
The fields of the conversion specification have the following meanings:
Conversions normally consume arguments in the order that they
are presented. However, it is possible to consume arguments
out of order, and reuse an argument for more than one
conversion specification (although the behavior is undefined
if the same argument is requested with different types), by
specifying pos, which is a decimal integer followed by
’$’. The integer must be between 1 and <NL_ARGMAX> from
limits.h, and if argument %n$ is requested, all earlier
arguments must be requested somewhere within format. If
positional parameters are used, then all conversion
specifications except for %% must specify a position.
This positional parameters method is a POSIX extension to the C
standard definition for the functions.
flags is an optional sequence of characters which control
output justification, numeric signs, decimal points, trailing
zeros, and octal and hex prefixes. The flag characters are
minus (-), plus (+), space ( ), zero (0), sharp
(#), and quote ('). They can appear in any
combination, although not all flags can be used for all
conversion specification types.
'A POSIX extension to the C standard. However, this
implementation presently treats it as a no-op, which
is the default behavior for the C locale, anyway. (If
it did what it is supposed to, when type were i,
d, u, f, F, g, or G, the
integer portion of the conversion would be formatted
with thousands’ grouping wide characters.)
-The result of the conversion is left justified, and the right is padded with blanks. If you do not use this flag, the result is right justified, and padded on the left.
+The result of a signed conversion (as
determined by type of d, i, a,
A, e, E, f, F, g, or
G) will always begin with a plus or minus
sign. (If you do not use this flag, positive
values do not begin with a plus sign.)
" " (space)If the first character of a signed conversion
specification is not a sign, or if a signed
conversion results in no characters, the
result will begin with a space. If the space
( ) flag and the plus (+) flag both
appear, the space flag is ignored.
0If the type character is d, i,
o, u, x, X, a, A,
e, E, f, F, g, or G: leading
zeros are used to pad the field width
(following any indication of sign or base); no
spaces are used for padding. If the zero
(0) and minus (-) flags both appear,
the zero (0) flag will be ignored. For
d, i, o, u, x, and X
conversions, if a precision prec is
specified, the zero (0) flag is ignored.
Note that 0 is interpreted as a flag, not
as the beginning of a field width.
#The result is to be converted to an alternative form, according to the type character.
The alternative form output with the # flag depends on the type character:
oIncreases precision to force the first digit of the result to be a zero.
xA non-zero result will have a 0x
prefix.
XA non-zero result will have a 0X
prefix.
a, A, e, E, f, or FThe result will always contain a decimal point even if no digits follow the point. (Normally, a decimal point appears only if a digit follows it.) Trailing zeros are removed.
g or GThe result will always contain a decimal point even if no digits follow the point. Trailing zeros are not removed.
all othersUndefined.
width is an optional minimum field width. You can
either specify it directly as a decimal integer, or
indirectly by using instead an asterisk (*), in
which case an int argument is used as the field
width. If positional arguments are used, then the
width must also be specified positionally as *m$,
with m as a decimal integer. Negative field widths
are treated as specifying the minus (-) flag for
left justfication, along with a positive field width.
The resulting format may be wider than the specified
width.
prec is an optional field; if present, it is
introduced with ‘.’ (a period). You can specify
the precision either directly as a decimal integer or
indirectly by using an asterisk (*), in which case
an int argument is used as the precision. If
positional arguments are used, then the precision must
also be specified positionally as *m$, with m as a
decimal integer. Supplying a negative precision is
equivalent to omitting the precision. If only a
period is specified the precision is zero. The effect
depends on the conversion type.
d, i, o, u, x, or XMinimum number of digits to appear. If no precision is given, defaults to 1.
a or ANumber of digits to appear after the decimal point. If no precision is given, the precision defaults to the minimum needed for an exact representation.
e, E, f or FNumber of digits to appear after the decimal point. If no precision is given, the precision defaults to 6.
g or GMaximum number of significant digits. A precision of 0 is treated the same as a precision of 1. If no precision is given, the precision defaults to 6.
s or SMaximum number of characters to print from the string. If no precision is given, the entire string is printed.
all othersundefined.
size is an optional modifier that changes the data type that the corresponding argument has. Behavior is unspecified if a size is given that does not match the type.
hhWith d, i, o, u, x, or
X, specifies that the argument should be
converted to a signed char or unsigned
char before printing.
With n, specifies that the argument is a
pointer to a signed char.
hWith d, i, o, u, x, or
X, specifies that the argument should be
converted to a short or unsigned short
before printing.
With n, specifies that the argument is a
pointer to a short.
lWith d, i, o, u, x, or
X, specifies that the argument is a
long or unsigned long.
With c, specifies that the argument has
type wint_t.
With s, specifies that the argument is a
pointer to wchar_t.
With n, specifies that the argument is a
pointer to a long.
With a, A, e, E, f, F,
g, or G, has no effect (because of
vararg promotion rules, there is no need to
distinguish between float and double).
llWith d, i, o, u, x, or
X, specifies that the argument is a
long long or unsigned long long.
With n, specifies that the argument is a
pointer to a long long.
jWith d, i, o, u, x, or
X, specifies that the argument is an
intmax_t or uintmax_t.
With n, specifies that the argument is a
pointer to an intmax_t.
zWith d, i, o, u, x, or
X, specifies that the argument is a size_t.
With n, specifies that the argument is a
pointer to a size_t.
tWith d, i, o, u, x, or
X, specifies that the argument is a
ptrdiff_t.
With n, specifies that the argument is a
pointer to a ptrdiff_t.
LWith a, A, e, E, f, F,
g, or G, specifies that the argument
is a long double.
type specifies what kind of conversion wprintf
performs. Here is a table of these:
%Prints the percent character (%).
cIf no l qualifier is present, the int argument shall
be converted to a wide character as if by calling
the btowc() function and the resulting wide character
shall be written. Otherwise, the wint_t argument
shall be converted to wchar_t, and written.
CShort for %lc. A POSIX extension to the C standard.
sIf no l qualifier is present, the application
shall ensure that the argument is a pointer to a
character array containing a character sequence
beginning in the initial shift state. Characters
from the array shall be converted as if by repeated
calls to the mbrtowc() function, with the conversion
state described by an mbstate_t object initialized to
zero before the first character is converted, and
written up to (but not including) the terminating
null wide character. If the precision is specified,
no more than that many wide characters shall be
written. If the precision is not specified, or is
greater than the size of the array, the application
shall ensure that the array contains a null wide
character.
If an l qualifier is present, the application
shall ensure that the argument is a pointer to an
array of type wchar_t. Wide characters from the array
shall be written up to (but not including) a
terminating null wide character. If no precision is
specified, or is greater than the size of the array,
the application shall ensure that the array contains
a null wide character. If a precision is specified,
no more than that many wide characters shall be
written.
SShort for %ls. A POSIX extension to the C standard.
d or iPrints a signed decimal integer; takes an
int. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
oPrints an unsigned octal integer; takes an
unsigned. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
uPrints an unsigned decimal integer; takes an
unsigned. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
xPrints an unsigned hexadecimal integer (using
abcdef as digits beyond 9); takes an
unsigned. Leading zeros are inserted as
necessary to reach the precision. A value of 0 with
a precision of 0 produces an empty string.
XLike x, but uses ABCDEF as digits
beyond 9.
fPrints a signed value of the form
[-]9999.9999, with the precision
determining how many digits follow the decimal
point; takes a double (remember that
float promotes to double as a vararg).
The low order digit is rounded to even. If
the precision results in at most DECIMAL_DIG
digits, the result is rounded correctly; if
more than DECIMAL_DIG digits are printed, the
result is only guaranteed to round back to the
original value.
If the value is infinite, the result is
inf, and no zero padding is performed. If
the value is not a number, the result is
nan, and no zero padding is performed.
FLike f, but uses INF and NAN for
non-finite numbers.
ePrints a signed value of the form
[-]9.9999e[+|-]999; takes a double.
The digit before the decimal point is non-zero
if the value is non-zero. The precision
determines how many digits appear between
. and e, and the exponent always
contains at least two digits. The value zero
has an exponent of zero. If the value is not
finite, it is printed like f.
ELike e, but using E to introduce the
exponent, and like F for non-finite
values.
gPrints a signed value in either f or e
form, based on the given value and
precision—an exponent less than -4 or
greater than the precision selects the e
form. Trailing zeros and the decimal point
are printed only if necessary; takes a
double.
GLike g, except use F or E form.
aPrints a signed value of the form
[-]0x1.ffffp[+|-]9; takes a double.
The letters abcdef are used for digits
beyond 9. The precision determines how
many digits appear after the decimal point.
The exponent contains at least one digit, and
is a decimal value representing the power of
2; a value of 0 has an exponent of 0.
Non-finite values are printed like f.
ALike a, except uses X, P, and
ABCDEF instead of lower case.
nTakes a pointer to int, and stores a count
of the number of bytes written so far. No
output is created.
pTakes a pointer to void, and prints it in
an implementation-defined format. This
implementation is similar to %#tx), except
that 0x appears even for the NULL pointer.
mPrints the output of strerror(errno); no
argument is required. A GNU extension.
_wprintf_r, _fwprintf_r, _swprintf_r, are simply
reentrant versions of the functions above.
Returns
On success, swprintf return the number of wide characters in
the output string, except the concluding NUL is not counted.
wprintf and fwprintf return the number of characters transmitted.
If an error occurs, the result of wprintf, fwprintf, and
swprintf is a negative value. For wprintf and fwprintf,
errno may be set according to fputwc. For swprintf, errno
may be set to EOVERFLOW if size is greater than INT_MAX / sizeof (wchar_t),
or when the output does not fit into size wide characters (including the
terminating wide NULL).
Bugs
The “”’ (quote) flag does not work when locale’s thousands_sep is not empty.
Portability
POSIX-1.2008 with extensions; C99 (compliant except for POSIX extensions).
Depending on how newlib was configured, not all format specifiers are supported.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: tmpfile—create a temporary file, Previous: swprintf, fwprintf, wprintf—wide character format output, Up: Input and Output (stdio.h) [Contents][Index]
swscanf, fwscanf, wscanf—scan and format wide character inputSynopsis
#include <stdio.h>
int wscanf(const wchar_t *__restrict format, ...);
int fwscanf(FILE *__restrict fd,
const wchar_t *__restrict format, ...);
int swscanf(const wchar_t *__restrict str,
const wchar_t *__restrict format, ...);
int _wscanf_r(struct _reent *ptr, const wchar_t *format, ...);
int _fwscanf_r(struct _reent *ptr, FILE *fd,
const wchar_t *format, ...);
int _swscanf_r(struct _reent *ptr, const wchar_t *str,
const wchar_t *format, ...);
Description
wscanf scans a series of input fields from standard input,
one wide character at a time. Each field is interpreted according to
a format specifier passed to wscanf in the format string at
*format. wscanf stores the interpreted input from
each field at the address passed to it as the corresponding argument
following format. You must supply the same number of
format specifiers and address arguments as there are input fields.
There must be sufficient address arguments for the given format specifiers; if not the results are unpredictable and likely disasterous. Excess address arguments are merely ignored.
wscanf often produces unexpected results if the input diverges from
an expected pattern. Since the combination of gets or fgets
followed by swscanf is safe and easy, that is the preferred way
to be certain that a program is synchronized with input at the end
of a line.
fwscanf and swscanf are identical to wscanf, other than the
source of input: fwscanf reads from a file, and swscanf
from a string.
The routines _wscanf_r, _fwscanf_r, and _swscanf_r are reentrant
versions of wscanf, fwscanf, and swscanf that take an additional
first argument pointing to a reentrancy structure.
The string at *format is a wide character sequence composed
of zero or more directives. Directives are composed of
one or more whitespace characters, non-whitespace characters,
and format specifications.
Whitespace characters are blank ( ), tab (\t), or
newline (\n).
When wscanf encounters a whitespace character in the format string
it will read (but not store) all consecutive whitespace characters
up to the next non-whitespace character in the input.
Non-whitespace characters are all other ASCII characters except the
percent sign (%). When wscanf encounters a non-whitespace
character in the format string it will read, but not store
a matching non-whitespace character.
Format specifications tell wscanf to read and convert characters
from the input field into specific types of values, and store then
in the locations specified by the address arguments.
Trailing whitespace is left unread unless explicitly matched in the format string.
The format specifiers must begin with a percent sign (%)
and have the following form:
%[*][width][size]type
Each format specification begins with the percent character (%).
The other fields are:
an optional marker; if present, it suppresses interpretation and assignment of this input field.
an optional maximum field width: a decimal integer,
which controls the maximum number of characters that
will be read before converting the current input field. If the
input field has fewer than width characters, wscanf
reads all the characters in the field, and then
proceeds with the next field and its format specification.
If a whitespace or a non-convertable wide character occurs
before width character are read, the characters up
to that character are read, converted, and stored.
Then wscanf proceeds to the next format specification.
h, j, l, L, t, and z are optional size
characters which override the default way that wscanf
interprets the data type of the corresponding argument.
| Modifier | Type(s) | |
|---|---|---|
| hh | d, i, o, u, x, n | convert input to char, store in char object |
| h | d, i, o, u, x, n | convert input to short, store in short object |
| h | e, f, c, s, p | no effect |
| j | d, i, o, u, x, n | convert input to intmax_t, store in intmax_t object |
| j | all others | no effect |
| l | d, i, o, u, x, n | convert input to long, store in long object |
| l | e, f, g | convert input to double, store in a double object |
| l | c, s, [ | the input is stored in a wchar_t object |
| l | p | no effect |
| ll | d, i, o, u, x, n | convert to long long, store in long long object |
| L | d, i, o, u, x, n | convert to long long, store in long long object |
| L | e, f, g, E, G | convert to long double, store in long double object |
| L | all others | no effect |
| t | d, i, o, u, x, n | convert input to ptrdiff_t, store in ptrdiff_t object |
| t | all others | no effect |
| z | d, i, o, u, x, n | convert input to size_t, store in size_t object |
| z | all others | no effect |
A character to specify what kind of conversion
wscanf performs. Here is a table of the conversion
characters:
%No conversion is done; the percent character (%) is stored.
cScans one wide character. Corresponding arg: (char *arg).
Otherwise, if an l specifier is present, the corresponding
arg is a (wchar_t *arg).
sReads a character string into the array supplied.
Corresponding arg: (char arg[]).
If an l specifier is present, the corresponding arg is a (wchar_t *arg).
[pattern]Reads a non-empty character string into memory
starting at arg. This area must be large
enough to accept the sequence and a
terminating null character which will be added
automatically. (pattern is discussed in the paragraph following
this table). Corresponding arg: (char *arg).
If an l specifier is present, the corresponding arg is
a (wchar_t *arg).
dReads a decimal integer into the corresponding arg: (int *arg).
oReads an octal integer into the corresponding arg: (int *arg).
uReads an unsigned decimal integer into the corresponding
arg: (unsigned int *arg).
x,XRead a hexadecimal integer into the corresponding arg:
(int *arg).
e, f, gRead a floating-point number into the corresponding arg:
(float *arg).
E, F, GRead a floating-point number into the corresponding arg:
(double *arg).
iReads a decimal, octal or hexadecimal integer into the
corresponding arg: (int *arg).
nStores the number of characters read in the corresponding
arg: (int *arg).
pStores a scanned pointer. ANSI C leaves the details
to each implementation; this implementation treats
%p exactly the same as %U. Corresponding
arg: (void **arg).
A pattern of characters surrounded by square brackets can be used
instead of the s type character. pattern is a set of
characters which define a search set of possible characters making up
the wscanf input field. If the first character in the brackets is a
caret (^), the search set is inverted to include all ASCII characters
except those between the brackets. There is no range facility as is
defined in the corresponding non-wide character scanf functions.
Ranges are not part of the POSIX standard.
Here are some pattern examples:
%[abcd]matches wide character strings containing only
a, b, c, and d.
%[^abcd]matches wide character strings containing any characters except
a, b, c, or d.
%[A-DW-Z]Note: No wide character ranges, so this expression matches wide
character strings containing A, -, D, W, Z.
Floating point numbers (for field types e, f, g, E,
F, G) must correspond to the following general form:
[+/-] ddddd[.]ddd [E|e[+|-]ddd]
where objects inclosed in square brackets are optional, and ddd
represents decimal, octal, or hexadecimal digits.
Returns
wscanf returns the number of input fields successfully
scanned, converted and stored; the return value does
not include scanned fields which were not stored.
If wscanf attempts to read at end-of-file, the return
value is EOF.
If no fields were stored, the return value is 0.
wscanf might stop scanning a particular field before
reaching the normal field end character, or may
terminate entirely.
wscanf stops scanning and storing the current field
and moves to the next input field (if any)
in any of the following situations:
*) appears
after the % in the format specification; the current
input field is scanned but not stored.
Z is read when the format is decimal).
When wscanf stops scanning the current input field for one of
these reasons, the next character is considered unread and
used as the first character of the following input field, or the
first character in a subsequent read operation on the input.
wscanf will terminate under the following circumstances:
WEOF.
When the format string contains a wide character sequence that is
not part of a format specification, the same wide character
sequence must appear in the input; wscanf will
scan but not store the matched characters. If a
conflict occurs, the first conflicting wide character remains in the
input as if it had never been read.
Portability
wscanf is C99, POSIX-1.2008.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: tmpnam, tempnam—name for a temporary file, Previous: swscanf, fwscanf, wscanf—scan and format wide character input, Up: Input and Output (stdio.h) [Contents][Index]
tmpfile—create a temporary fileSynopsis
#include <stdio.h> FILE *tmpfile(void); FILE *_tmpfile_r(struct _reent *reent);
Description
Create a temporary file (a file which will be deleted automatically),
using a name generated by tmpnam. The temporary file is opened with
the mode "wb+", permitting you to read and write anywhere in it
as a binary file (without any data transformations the host system may
perform for text files).
The alternate function _tmpfile_r is a reentrant version. The
argument reent is a pointer to a reentrancy structure.
Returns
tmpfile normally returns a pointer to the temporary file. If no
temporary file could be created, the result is NULL, and errno
records the reason for failure.
Portability
Both ANSI C and the System V Interface Definition (Issue 2) require
tmpfile.
Supporting OS subroutines required: close, fstat, getpid,
isatty, lseek, open, read, sbrk, write.
tmpfile also requires the global pointer environ.
Next: ungetc—push data back into a stream, Previous: tmpfile—create a temporary file, Up: Input and Output (stdio.h) [Contents][Index]
tmpnam, tempnam—name for a temporary fileSynopsis
#include <stdio.h> char *tmpnam(char *s); char *tempnam(char *dir, char *pfx); char *_tmpnam_r(struct _reent *reent, char *s); char *_tempnam_r(struct _reent *reent, char *dir, char *pfx);
Description
Use either of these functions to generate a name for a temporary file.
The generated name is guaranteed to avoid collision with other files
(for up to TMP_MAX calls of either function).
tmpnam generates file names with the value of P_tmpdir
(defined in ‘stdio.h’) as the leading directory component of the path.
You can use the tmpnam argument s to specify a suitable area
of memory for the generated filename; otherwise, you can call
tmpnam(NULL) to use an internal static buffer.
tempnam allows you more control over the generated filename: you
can use the argument dir to specify the path to a directory for
temporary files, and you can use the argument pfx to specify a
prefix for the base filename.
If dir is NULL, tempnam will attempt to use the value of
environment variable TMPDIR instead; if there is no such value,
tempnam uses the value of P_tmpdir (defined in ‘stdio.h’).
If you don’t need any particular prefix to the basename of temporary
files, you can pass NULL as the pfx argument to tempnam.
_tmpnam_r and _tempnam_r are reentrant versions of tmpnam
and tempnam respectively. The extra argument reent is a
pointer to a reentrancy structure.
Warnings
The generated filenames are suitable for temporary files, but do not
in themselves make files temporary. Files with these names must still
be explicitly removed when you no longer want them.
If you supply your own data area s for tmpnam, you must ensure
that it has room for at least L_tmpnam elements of type char.
Returns
Both tmpnam and tempnam return a pointer to the newly
generated filename.
Portability
ANSI C requires tmpnam, but does not specify the use of
P_tmpdir. The System V Interface Definition (Issue 2) requires
both tmpnam and tempnam.
Supporting OS subroutines required: close, fstat, getpid,
isatty, lseek, open, read, sbrk, write.
The global pointer environ is also required.
Next: ungetwc—push wide character data back into a stream, Previous: tmpnam, tempnam—name for a temporary file, Up: Input and Output (stdio.h) [Contents][Index]
ungetc—push data back into a streamSynopsis
#include <stdio.h> int ungetc(int c, FILE *stream); int _ungetc_r(struct _reent *reent, int c, FILE *stream);
Description
ungetc is used to return bytes back to stream to be read again.
If c is EOF, the stream is unchanged. Otherwise, the unsigned
char c is put back on the stream, and subsequent reads will see
the bytes pushed back in reverse order. Pushed byes are lost if the
stream is repositioned, such as by fseek, fsetpos, or
rewind.
The underlying file is not changed, but it is possible to push back something different than what was originally read. Ungetting a character will clear the end-of-stream marker, and decrement the file position indicator. Pushing back beyond the beginning of a file gives unspecified behavior.
The alternate function _ungetc_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
The character pushed back, or EOF on error.
Portability
ANSI C requires ungetc, but only requires a pushback buffer of one
byte; although this implementation can handle multiple bytes, not all
can. Pushing back a signed char is a common application bug.
Supporting OS subroutines required: sbrk.
Next: vfprintf, vprintf, vsprintf, vsnprintf, vasprintf, vasnprintf—format argument list, Previous: ungetc—push data back into a stream, Up: Input and Output (stdio.h) [Contents][Index]
ungetwc—push wide character data back into a streamSynopsis
#include <stdio.h> #include <wchar.h> wint_t ungetwc(wint_t wc, FILE *stream); wint_t _ungetwc_r(struct _reent *reent, wint_t wc, FILE *stream);
Description
ungetwc is used to return wide characters back to stream to be
read again. If wc is WEOF, the stream is unchanged. Otherwise, the
wide character wc is put back on the stream, and subsequent reads will see
the wide chars pushed back in reverse order. Pushed wide chars are lost if the
stream is repositioned, such as by fseek, fsetpos, or
rewind.
The underlying file is not changed, but it is possible to push back something different than what was originally read. Ungetting a character will clear the end-of-stream marker, and decrement the file position indicator. Pushing back beyond the beginning of a file gives unspecified behavior.
The alternate function _ungetwc_r is a reentrant version. The
extra argument reent is a pointer to a reentrancy structure.
Returns
The wide character pushed back, or WEOF on error.
Portability
C99
Next: vfscanf, vscanf, vsscanf—format argument list, Previous: ungetwc—push wide character data back into a stream, Up: Input and Output (stdio.h) [Contents][Index]
vfprintf, vprintf, vsprintf, vsnprintf, vasprintf, vasnprintf—format argument listSynopsis
#include <stdio.h>
#include <stdarg.h>
int vprintf(const char *fmt, va_list list);
int vfprintf(FILE *fp, const char *fmt, va_list list);
int vsprintf(char *str, const char *fmt, va_list list);
int vsnprintf(char *str, size_t size, const char *fmt,
va_list list);
int vasprintf(char **strp, const char *fmt, va_list list);
char *vasnprintf(char *str, size_t *size, const char *fmt,
va_list list);
int _vprintf_r(struct _reent *reent, const char *fmt,
va_list list);
int _vfprintf_r(struct _reent *reent, FILE *fp,
const char *fmt, va_list list);
int _vsprintf_r(struct _reent *reent, char *str,
const char *fmt, va_list list);
int _vasprintf_r(struct _reent *reent, char **str,
const char *fmt, va_list list);
int _vsnprintf_r(struct _reent *reent, char *str,
size_t size, const char *fmt, va_list list);
char *_vasnprintf_r(struct _reent *reent, char *str,
size_t *size, const char *fmt, va_list list);
Description
vprintf, vfprintf, vasprintf, vsprintf, vsnprintf,
and vasnprintf are (respectively) variants of printf,
fprintf, asprintf, sprintf, snprintf, and
asnprintf. They differ only in allowing their caller to pass the
variable argument list as a va_list object (initialized by
va_start) rather than directly accepting a variable number of
arguments. The caller is responsible for calling va_end.
_vprintf_r, _vfprintf_r, _vasprintf_r, _vsprintf_r,
_vsnprintf_r, and _vasnprintf_r are reentrant versions of the
above.
Returns
The return values are consistent with the corresponding functions.
Portability
ANSI C requires vprintf, vfprintf, vsprintf, and
vsnprintf. The remaining functions are newlib extensions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: vfwprintf, vwprintf, vswprintf—wide character format argument list, Previous: vfprintf, vprintf, vsprintf, vsnprintf, vasprintf, vasnprintf—format argument list, Up: Input and Output (stdio.h) [Contents][Index]
vfscanf, vscanf, vsscanf—format argument listSynopsis
#include <stdio.h>
#include <stdarg.h>
int vscanf(const char *fmt, va_list list);
int vfscanf(FILE *fp, const char *fmt, va_list list);
int vsscanf(const char *str, const char *fmt, va_list list);
int _vscanf_r(struct _reent *reent, const char *fmt,
va_list list);
int _vfscanf_r(struct _reent *reent, FILE *fp, const char *fmt,
va_list list);
int _vsscanf_r(struct _reent *reent, const char *str,
const char *fmt, va_list list);
Description
vscanf, vfscanf, and vsscanf are (respectively) variants
of scanf, fscanf, and sscanf. They differ only in
allowing their caller to pass the variable argument list as a
va_list object (initialized by va_start) rather than
directly accepting a variable number of arguments.
Returns
The return values are consistent with the corresponding functions:
vscanf returns the number of input fields successfully scanned,
converted, and stored; the return value does not include scanned
fields which were not stored.
If vscanf attempts to read at end-of-file, the return value
is EOF.
If no fields were stored, the return value is 0.
The routines _vscanf_r, _vfscanf_f, and _vsscanf_r are
reentrant versions which take an additional first parameter which points to the
reentrancy structure.
Portability
These are GNU extensions.
Supporting OS subroutines required:
Next: vfwscanf, vwscanf, vswscanf—scan and format argument list from wide character input, Previous: vfscanf, vscanf, vsscanf—format argument list, Up: Input and Output (stdio.h) [Contents][Index]
vfwprintf, vwprintf, vswprintf—wide character format argument listSynopsis
#include <stdio.h>
#include <stdarg.h>
#include <wchar.h>
int vwprintf(const wchar_t *__restrict fmt, va_list list);
int vfwprintf(FILE *__restrict fp,
const wchar_t *__restrict fmt, va_list list);
int vswprintf(wchar_t * __restrict str, size_t size,
const wchar_t *__ restrict fmt, va_list list);
int _vwprintf_r(struct _reent *reent, const wchar_t *fmt,
va_list list);
int _vfwprintf_r(struct _reent *reent, FILE *fp,
const wchar_t *fmt, va_list list);
int _vswprintf_r(struct _reent *reent, wchar_t *str,
size_t size, const wchar_t *fmt, va_list list);
Description
vwprintf, vfwprintf and vswprintf are (respectively) variants
of wprintf, fwprintf and swprintf. They differ only in allowing
their caller to pass the variable argument list as a va_list object
(initialized by va_start) rather than directly accepting a variable
number of arguments. The caller is responsible for calling va_end.
_vwprintf_r, _vfwprintf_r and _vswprintf_r are reentrant
versions of the above.
Returns
The return values are consistent with the corresponding functions.
Portability
POSIX-1.2008 with extensions; C99 (compliant except for POSIX extensions).
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
See Also
wprintf, fwprintf and swprintf.
Next: viprintf, vfiprintf, vsiprintf, vsniprintf, vasiprintf, vasniprintf—format argument list (integer only), Previous: vfwprintf, vwprintf, vswprintf—wide character format argument list, Up: Input and Output (stdio.h) [Contents][Index]
vfwscanf, vwscanf, vswscanf—scan and format argument list from wide character inputSynopsis
#include <stdio.h>
#include <stdarg.h>
int vwscanf(const wchar_t *__restrict fmt, va_list list);
int vfwscanf(FILE *__restrict fp,
const wchar_t *__restrict fmt, va_list list);
int vswscanf(const wchar_t *__restrict str,
const wchar_t *__restrict fmt, va_list list);
int _vwscanf(struct _reent *reent, const wchar_t *fmt,
va_list list);
int _vfwscanf(struct _reent *reent, FILE *fp,
const wchar_t *fmt, va_list list);
int _vswscanf(struct _reent *reent, const wchar_t *str,
const wchar_t *fmt, va_list list);
Description
vwscanf, vfwscanf, and vswscanf are (respectively) variants
of wscanf, fwscanf, and swscanf. They differ only in
allowing their caller to pass the variable argument list as a
va_list object (initialized by va_start) rather than
directly accepting a variable number of arguments.
Returns
The return values are consistent with the corresponding functions:
vwscanf returns the number of input fields successfully scanned,
converted, and stored; the return value does not include scanned
fields which were not stored.
If vwscanf attempts to read at end-of-file, the return value
is EOF.
If no fields were stored, the return value is 0.
The routines _vwscanf, _vfwscanf, and _vswscanf are
reentrant versions which take an additional first parameter which points
to the reentrancy structure.
Portability
C99, POSIX-1.2008
Next: viscanf, vfiscanf, vsiscanf—format argument list, Previous: vfwscanf, vwscanf, vswscanf—scan and format argument list from wide character input, Up: Input and Output (stdio.h) [Contents][Index]
viprintf, vfiprintf, vsiprintf, vsniprintf, vasiprintf, vasniprintf—format argument list (integer only)Synopsis
#include <stdio.h>
#include <stdarg.h>
int viprintf(const char *fmt, va_list list);
int vfiprintf(FILE *fp, const char *fmt, va_list list);
int vsiprintf(char *str, const char *fmt, va_list list);
int vsniprintf(char *str, size_t size, const char *fmt,
va_list list);
int vasiprintf(char **strp, const char *fmt, va_list list);
char *vasniprintf(char *str, size_t *size, const char *fmt,
va_list list);
int _viprintf_r(struct _reent *reent, const char *fmt,
va_list list);
int _vfiprintf_r(struct _reent *reent, FILE *fp,
const char *fmt, va_list list);
int _vsiprintf_r(struct _reent *reent, char *str,
const char *fmt, va_list list);
int _vsniprintf_r(struct _reent *reent, char *str,
size_t size, const char *fmt, va_list list);
int _vasiprintf_r(struct _reent *reent, char **str,
const char *fmt, va_list list);
char *_vasniprintf_r(struct _reent *reent, char *str,
size_t *size, const char *fmt, va_list list);
Description
viprintf, vfiprintf, vasiprintf, vsiprintf,
vsniprintf, and vasniprintf are (respectively) variants of
iprintf, fiprintf, asiprintf, siprintf, sniprintf,
and asniprintf. They differ only in allowing their caller to pass
the variable argument list as a va_list object (initialized by
va_start) rather than directly accepting a variable number of
arguments. The caller is responsible for calling va_end.
_viprintf_r, _vfiprintf_r, _vasiprintf_r,
_vsiprintf_r, _vsniprintf_r, and _vasniprintf_r are
reentrant versions of the above.
Returns
The return values are consistent with the corresponding functions:
Portability
All of these functions are newlib extensions.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
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viscanf, vfiscanf, vsiscanf—format argument listSynopsis
#include <stdio.h>
#include <stdarg.h>
int viscanf(const char *fmt, va_list list);
int vfiscanf(FILE *fp, const char *fmt, va_list list);
int vsiscanf(const char *str, const char *fmt, va_list list);
int _viscanf_r(struct _reent *reent, const char *fmt,
va_list list);
int _vfiscanf_r(struct _reent *reent, FILE *fp, const char *fmt,
va_list list);
int _vsiscanf_r(struct _reent *reent, const char *str,
const char *fmt, va_list list);
Description
viscanf, vfiscanf, and vsiscanf are (respectively) variants
of iscanf, fiscanf, and siscanf. They differ only in
allowing their caller to pass the variable argument list as a
va_list object (initialized by va_start) rather than
directly accepting a variable number of arguments.
Returns
The return values are consistent with the corresponding functions:
viscanf returns the number of input fields successfully scanned,
converted, and stored; the return value does not include scanned
fields which were not stored.
If viscanf attempts to read at end-of-file, the return value
is EOF.
If no fields were stored, the return value is 0.
The routines _viscanf_r, _vfiscanf_f, and _vsiscanf_r are
reentrant versions which take an additional first parameter which points to the
reentrancy structure.
Portability
These are newlib extensions.
Supporting OS subroutines required:
Next: Strings and Memory (string.h), Previous: Input and Output (stdio.h), Up: The Red Hat newlib C Library [Contents][Index]
This chapter comprises additional functions to manage large files which are potentially larger than 2GB.
The underlying facilities for input and output depend on the host system, but these functions provide a uniform interface.
The corresponding declarations are in stdio.h.
fdopen64—turn open large file into a streamfopen64—open a large filefreopen64—open a large file using an existing file descriptorftello64—return position in a stream or filefseeko64—set file position for large filefgetpos64—record position in a large stream or filefsetpos64—restore position of a large stream or filetmpfile64—create a large temporary filefdopen64—turn open large file into a streamSynopsis
#include <stdio.h>
FILE *fdopen64(int fd, const char *mode);
FILE *_fdopen64_r(void *reent,
int fd, const char *mode);
Description
fdopen64 produces a file descriptor of type FILE *, from a
descriptor for an already-open file (returned, for example, by the
system subroutine open rather than by fopen).
The mode argument has the same meanings as in fopen.
Returns
File pointer or NULL, as for fopen.
Next: freopen64—open a large file using an existing file descriptor, Previous: fdopen64—turn open large file into a stream, Up: Large File Input and Output (stdio.h) [Contents][Index]
fopen64—open a large fileSynopsis
#include <stdio.h>
FILE *fopen64(const char *file, const char *mode);
FILE *_fopen64_r(void *reent,
const char *file, const char *mode);
Description
fopen64 is identical to fopen except it opens a large file that
is potentially >2GB in size. See fopen for further details.
Returns
fopen64 return a file pointer which you can use for other file
operations, unless the file you requested could not be opened; in that
situation, the result is NULL. If the reason for failure was an
invalid string at mode, errno is set to EINVAL.
Portability
fopen64 is a glibc extension.
Supporting OS subroutines required: close, fstat64, isatty,
lseek64, open64, read, sbrk, write.
Next: ftello64—return position in a stream or file, Previous: fopen64—open a large file, Up: Large File Input and Output (stdio.h) [Contents][Index]
freopen64—open a large file using an existing file descriptorSynopsis
#include <stdio.h>
FILE *freopen64(const char *file, const char *mode,
FILE *fp);
FILE *_freopen64_r(struct _reent *ptr, const char *file,
const char *mode, FILE *fp);
Description
Use this variant of fopen64 if you wish to specify a particular file
descriptor fp (notably stdin, stdout, or stderr) for
the file.
If fp was associated with another file or stream, freopen64
closes that other file or stream (but ignores any errors while closing
it).
file and mode are used just as in fopen.
If file is NULL, the underlying stream is modified rather than
closed. The file cannot be given a more permissive access mode (for
example, a mode of "w" will fail on a read-only file descriptor),
but can change status such as append or binary mode. If modification
is not possible, failure occurs.
Returns
If successful, the result is the same as the argument fp. If the
file cannot be opened as specified, the result is NULL.
Portability
freopen is a glibc extension.
Supporting OS subroutines required: close, fstat, isatty,
lseek64, open64, read, sbrk, write.
Next: fseeko64—set file position for large file, Previous: freopen64—open a large file using an existing file descriptor, Up: Large File Input and Output (stdio.h) [Contents][Index]
ftello64—return position in a stream or fileSynopsis
#include <stdio.h> _off64_t ftello64(FILE *fp); _off64_t _ftello64_r(struct _reent *ptr, FILE *fp);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
The result of ftello64 is the current position for a large file
identified by fp. If you record this result, you can later
use it with fseeko64 to return the file to this
position. The difference between ftello and ftello64 is that
ftello returns off_t and ftello64 is designed to work
for large files (>2GB) and returns _off64_t.
In the current implementation, ftello64 simply uses a character
count to represent the file position; this is the same number that
would be recorded by fgetpos64.
The function exists only if the __LARGE64_FILES flag is defined.
An error occurs if the fp was not opened via fopen64.
Returns
ftello64 returns the file position, if possible. If it cannot do
this, it returns -1. Failure occurs on streams that do not support
positioning or not opened via fopen64; the global errno indicates
this condition with the value ESPIPE.
Portability
ftello64 is a glibc extension.
No supporting OS subroutines are required.
Next: fgetpos64—record position in a large stream or file, Previous: ftello64—return position in a stream or file, Up: Large File Input and Output (stdio.h) [Contents][Index]
fseeko64—set file position for large fileSynopsis
#include <stdio.h>
int fseeko64(FILE *fp, _off64_t offset, int whence);
int _fseeko64_r (struct _reent *ptr, FILE *fp,
_off64_t offset, int whence);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
You can use fseeko64 to set the position for the file identified by
fp that was opened via fopen64. The value of offset determines
the new position, in one of three ways selected by the value of whence
(defined as macros in ‘stdio.h’):
SEEK_SET—offset is the absolute file position (an offset
from the beginning of the file) desired. offset must be positive.
SEEK_CUR—offset is relative to the current file position.
offset can meaningfully be either positive or negative.
SEEK_END—offset is relative to the current end of file.
offset can meaningfully be either positive (to increase the size
of the file) or negative.
See ftello64 to determine the current file position.
Returns
fseeko64 returns 0 when successful. On failure, the
result is EOF. The reason for failure is indicated in errno:
either ESPIPE (the stream identified by fp doesn’t support
repositioning or wasn’t opened via fopen64) or EINVAL
(invalid file position).
Portability
fseeko64 is a glibc extension.
Supporting OS subroutines required: close, fstat64, isatty,
lseek64, read, sbrk, write.
Next: fsetpos64—restore position of a large stream or file, Previous: fseeko64—set file position for large file, Up: Large File Input and Output (stdio.h) [Contents][Index]
fgetpos64—record position in a large stream or fileSynopsis
#include <stdio.h>
int fgetpos64(FILE *fp, _fpos64_t *pos);
int _fgetpos64_r(struct _reent *ptr, FILE *fp,
_fpos64_t *pos);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
You can use fgetpos64 to report on the current position for a file
identified by fp that was opened by fopen64; fgetpos will write
a value representing that position at *pos. Later, you can
use this value with fsetpos64 to return the file to this
position.
In the current implementation, fgetpos64 simply uses a character
count to represent the file position; this is the same number that
would be returned by ftello64.
Returns
fgetpos64 returns 0 when successful. If fgetpos64 fails, the
result is 1. Failure occurs on streams that do not support
positioning or streams not opened via fopen64; the global errno
indicates these conditions with the value ESPIPE.
Portability
fgetpos64 is a glibc extension.
No supporting OS subroutines are required.
Next: tmpfile64—create a large temporary file, Previous: fgetpos64—record position in a large stream or file, Up: Large File Input and Output (stdio.h) [Contents][Index]
fsetpos64—restore position of a large stream or fileSynopsis
#include <stdio.h>
int fsetpos64(FILE *fp, const _fpos64_t *pos);
int _fsetpos64_r(struct _reent *ptr, FILE *fp,
const _fpos64_t *pos);
Description
Objects of type FILE can have a “position” that records how much
of the file your program has already read. Many of the stdio functions
depend on this position, and many change it as a side effect.
You can use fsetpos64 to return the large file identified by fp to a
previous position *pos (after first recording it with fgetpos64).
See fseeko64 for a similar facility.
Returns
fgetpos64 returns 0 when successful. If fgetpos64 fails, the
result is 1. The reason for failure is indicated in errno:
either ESPIPE (the stream identified by fp doesn’t support
64-bit repositioning) or EINVAL (invalid file position).
Portability
fsetpos64 is a glibc extension.
Supporting OS subroutines required: close, fstat, isatty,
lseek64, read, sbrk, write.
Previous: fsetpos64—restore position of a large stream or file, Up: Large File Input and Output (stdio.h) [Contents][Index]
tmpfile64—create a large temporary fileSynopsis
#include <stdio.h> FILE *tmpfile64(void); FILE *_tmpfile64_r(void *reent);
Description
Create a large temporary file (a file which will be deleted automatically),
using a name generated by tmpnam. The temporary file is opened with
the mode "wb+", permitting you to read and write anywhere in it
as a binary file (without any data transformations the host system may
perform for text files). The file may be larger than 2GB.
The alternate function _tmpfile64_r is a reentrant version. The
argument reent is a pointer to a reentrancy structure.
Both tmpfile64 and _tmpfile64_r are only defined if __LARGE64_FILES
is defined.
Returns
tmpfile64 normally returns a pointer to the temporary file. If no
temporary file could be created, the result is NULL, and errno
records the reason for failure.
Portability
tmpfile64 is a glibc extension.
Supporting OS subroutines required: close, fstat, getpid,
isatty, lseek64, open64, read, sbrk, write.
tmpfile64 also requires the global pointer environ.
Next: Wide Character Strings (wchar.h), Previous: Large File Input and Output (stdio.h), Up: The Red Hat newlib C Library [Contents][Index]
This chapter describes string-handling functions and functions for managing areas of memory. The corresponding declarations are in string.h.
bcmp—compare two memory areasbcopy—copy memory regionsbzero—initialize memory to zeroindex—search for character in stringmemccpy—copy memory regions with end-token checkmemchr—find character in memorymemcmp—compare two memory areasmemcpy—copy memory regionsmemmem—find memory segmentmemmove—move possibly overlapping memorymempcpy—copy memory regions and return end pointermemrchr—reverse search for character in memorymemset—set an area of memoryrawmemchr—find character in memoryrindex—reverse search for character in stringstpcpy—copy string returning a pointer to its endstpncpy—counted copy string returning a pointer to its endstrcasecmp—case-insensitive character string comparestrcasestr—case-insensitive character string searchstrcat—concatenate stringsstrchr—search for character in stringstrchrnul—search for character in stringstrcmp—character string comparestrcoll—locale-specific character string comparestrcpy—copy stringstrcspn—count characters not in stringstrerror, strerror_l—convert error number to stringstrerror_r—convert error number to string and copy to bufferstrlen—character string lengthstrlwr—force string to lowercasestrncasecmp—case-insensitive character string comparestrncat—concatenate stringsstrncmp—character string comparestrncpy—counted copy stringstrnstr—find string segmentstrnlen—character string lengthstrpbrk—find characters in stringstrrchr—reverse search for character in stringstrsignal—convert signal number to stringstrspn—find initial matchstrstr—find string segmentstrtok, strtok_r, strsep—get next token from a stringstrupr—force string to uppercasestrverscmp—version string comparestrxfrm—transform stringswab—swap adjacent byteswcscasecmp—case-insensitive wide character string comparewcsdup—wide character string duplicatewcsncasecmp—case-insensitive wide character string compare
Next: bcopy—copy memory regions, Up: Strings and Memory (string.h) [Contents][Index]
bcmp—compare two memory areasSynopsis
#include <strings.h> int bcmp(const void *s1, const void *s2, size_t n);
Description
This function compares not more than n bytes of the
object pointed to by s1 with the object pointed to by s2.
This function is identical to memcmp.
Returns
The function returns an integer greater than, equal to or
less than zero according to whether the object pointed to by
s1 is greater than, equal to or less than the object
pointed to by s2.
Portability
bcmp requires no supporting OS subroutines.
Next: bzero—initialize memory to zero, Previous: bcmp—compare two memory areas, Up: Strings and Memory (string.h) [Contents][Index]
bcopy—copy memory regionsSynopsis
#include <strings.h> void bcopy(const void *in, void *out, size_t n);
Description
This function copies n bytes from the memory region
pointed to by in to the memory region pointed to by
out.
This function is implemented in term of memmove.
Portability
bcopy requires no supporting OS subroutines.
Next: index—search for character in string, Previous: bcopy—copy memory regions, Up: Strings and Memory (string.h) [Contents][Index]
bzero—initialize memory to zeroSynopsis
#include <strings.h> void bzero(void *b, size_t length);
Description
bzero initializes length bytes of memory, starting at address
b, to zero.
Returns
bzero does not return a result.
Portability
bzero is in the Berkeley Software Distribution.
Neither ANSI C nor the System V Interface Definition (Issue 2) require
bzero.
bzero requires no supporting OS subroutines.
Next: memccpy—copy memory regions with end-token check, Previous: bzero—initialize memory to zero, Up: Strings and Memory (string.h) [Contents][Index]
index—search for character in stringSynopsis
#include <strings.h> char * index(const char *string, int c);
Description
This function finds the first occurence of c (converted to
a char) in the string pointed to by string (including the
terminating null character).
This function is identical to strchr.
Returns
Returns a pointer to the located character, or a null pointer
if c does not occur in string.
Portability
index requires no supporting OS subroutines.
Next: memchr—find character in memory, Previous: index—search for character in string, Up: Strings and Memory (string.h) [Contents][Index]
memccpy—copy memory regions with end-token checkSynopsis
#include <string.h>
void* memccpy(void *restrict out, const void *restrict in,
int endchar, size_t n);
Description
This function copies up to n bytes from the memory region
pointed to by in to the memory region pointed to by
out. If a byte matching the endchar is encountered,
the byte is copied and copying stops.
If the regions overlap, the behavior is undefined.
Returns
memccpy returns a pointer to the first byte following the
endchar in the out region. If no byte matching
endchar was copied, then NULL is returned.
Portability
memccpy is a GNU extension.
memccpy requires no supporting OS subroutines.
Next: memcmp—compare two memory areas, Previous: memccpy—copy memory regions with end-token check, Up: Strings and Memory (string.h) [Contents][Index]
memchr—find character in memorySynopsis
#include <string.h> void *memchr(const void *src, int c, size_t length);
Description
This function searches memory starting at *src for the
character c. The search only ends with the first
occurrence of c, or after length characters; in
particular, NUL does not terminate the search.
Returns
If the character c is found within length characters
of *src, a pointer to the character is returned. If
c is not found, then NULL is returned.
Portability
memchr is ANSI C.
memchr requires no supporting OS subroutines.
Next: memcpy—copy memory regions, Previous: memchr—find character in memory, Up: Strings and Memory (string.h) [Contents][Index]
memcmp—compare two memory areasSynopsis
#include <string.h> int memcmp(const void *s1, const void *s2, size_t n);
Description
This function compares not more than n characters of the
object pointed to by s1 with the object pointed to by s2.
Returns
The function returns an integer greater than, equal to or
less than zero according to whether the object pointed to by
s1 is greater than, equal to or less than the object
pointed to by s2.
Portability
memcmp is ANSI C.
memcmp requires no supporting OS subroutines.
Next: memmem—find memory segment, Previous: memcmp—compare two memory areas, Up: Strings and Memory (string.h) [Contents][Index]
memcpy—copy memory regionsSynopsis
#include <string.h>
void* memcpy(void *restrict out, const void *restrict in,
size_t n);
Description
This function copies n bytes from the memory region
pointed to by in to the memory region pointed to by
out.
If the regions overlap, the behavior is undefined.
Returns
memcpy returns a pointer to the first byte of the out
region.
Portability
memcpy is ANSI C.
memcpy requires no supporting OS subroutines.
Next: memmove—move possibly overlapping memory, Previous: memcpy—copy memory regions, Up: Strings and Memory (string.h) [Contents][Index]
memmem—find memory segmentSynopsis
#include <string.h>
void *memmem(const void *s1, size_t l1, const void *s2,
size_t l2);
Description
Locates the first occurrence in the memory region pointed to
by s1 with length l1 of the sequence of bytes pointed
to by s2 of length l2. If you already know the
lengths of your haystack and needle, memmem is much faster
than strstr.
Returns
Returns a pointer to the located segment, or a null pointer if
s2 is not found. If l2 is 0, s1 is returned.
Portability
memmem is a newlib extension.
memmem requires no supporting OS subroutines.
Next: mempcpy—copy memory regions and return end pointer, Previous: memmem—find memory segment, Up: Strings and Memory (string.h) [Contents][Index]
memmove—move possibly overlapping memorySynopsis
#include <string.h> void *memmove(void *dst, const void *src, size_t length);
Description
This function moves length characters from the block of
memory starting at *src to the memory starting at
*dst. memmove reproduces the characters correctly
at *dst even if the two areas overlap.
Returns
The function returns dst as passed.
Portability
memmove is ANSI C.
memmove requires no supporting OS subroutines.
Next: memrchr—reverse search for character in memory, Previous: memmove—move possibly overlapping memory, Up: Strings and Memory (string.h) [Contents][Index]
mempcpy—copy memory regions and return end pointerSynopsis
#include <string.h> void* mempcpy(void *out, const void *in, size_t n);
Description
This function copies n bytes from the memory region
pointed to by in to the memory region pointed to by
out.
If the regions overlap, the behavior is undefined.
Returns
mempcpy returns a pointer to the byte following the
last byte copied to the out region.
Portability
mempcpy is a GNU extension.
mempcpy requires no supporting OS subroutines.
Next: memset—set an area of memory, Previous: mempcpy—copy memory regions and return end pointer, Up: Strings and Memory (string.h) [Contents][Index]
memrchr—reverse search for character in memorySynopsis
#include <string.h> void *memrchr(const void *src, int c, size_t length);
Description
This function searches memory starting at length bytes
beyond *src backwards for the character c.
The search only ends with the first occurrence of c; in
particular, NUL does not terminate the search.
Returns
If the character c is found within length characters
of *src, a pointer to the character is returned. If
c is not found, then NULL is returned.
Portability
memrchr is a GNU extension.
memrchr requires no supporting OS subroutines.
Next: rawmemchr—find character in memory, Previous: memrchr—reverse search for character in memory, Up: Strings and Memory (string.h) [Contents][Index]
memset—set an area of memorySynopsis
#include <string.h> void *memset(void *dst, int c, size_t length);
Description
This function converts the argument c into an unsigned
char and fills the first length characters of the array
pointed to by dst to the value.
Returns
memset returns the value of dst.
Portability
memset is ANSI C.
memset requires no supporting OS subroutines.
Next: rindex—reverse search for character in string, Previous: memset—set an area of memory, Up: Strings and Memory (string.h) [Contents][Index]
rawmemchr—find character in memorySynopsis
#include <string.h> void *rawmemchr(const void *src, int c);
Description
This function searches memory starting at *src for the
character c. The search only ends with the first occurrence
of c; in particular, NUL does not terminate the search.
No bounds checking is performed, so this function should only
be used when it is certain that the character c will be found.
Returns
A pointer to the first occurance of character c.
Portability
rawmemchr is a GNU extension.
rawmemchr requires no supporting OS subroutines.
Next: stpcpy—copy string returning a pointer to its end, Previous: rawmemchr—find character in memory, Up: Strings and Memory (string.h) [Contents][Index]
rindex—reverse search for character in stringSynopsis
#include <string.h> char * rindex(const char *string, int c);
Description
This function finds the last occurence of c (converted to
a char) in the string pointed to by string (including the
terminating null character).
This function is identical to strrchr.
Returns
Returns a pointer to the located character, or a null pointer
if c does not occur in string.
Portability
rindex requires no supporting OS subroutines.
Next: stpncpy—counted copy string returning a pointer to its end, Previous: rindex—reverse search for character in string, Up: Strings and Memory (string.h) [Contents][Index]
stpcpy—copy string returning a pointer to its endSynopsis
#include <string.h> char *stpcpy(char *restrict dst, const char *restrict src);
Description
stpcpy copies the string pointed to by src
(including the terminating null character) to the array
pointed to by dst.
Returns
This function returns a pointer to the end of the destination string,
thus pointing to the trailing ’\0’.
Portability
stpcpy is a GNU extension, candidate for inclusion into POSIX/SUSv4.
stpcpy requires no supporting OS subroutines.
Next: strcasecmp—case-insensitive character string compare, Previous: stpcpy—copy string returning a pointer to its end, Up: Strings and Memory (string.h) [Contents][Index]
stpncpy—counted copy string returning a pointer to its endSynopsis
#include <string.h>
char *stpncpy(char *restrict dst, const char *restrict src,
size_t length);
Description
stpncpy copies not more than length characters from the
the string pointed to by src (including the terminating
null character) to the array pointed to by dst. If the
string pointed to by src is shorter than length
characters, null characters are appended to the destination
array until a total of length characters have been
written.
Returns
This function returns a pointer to the end of the destination string,
thus pointing to the trailing ’\0’, or, if the destination string is
not null-terminated, pointing to dst + n.
Portability
stpncpy is a GNU extension, candidate for inclusion into POSIX/SUSv4.
stpncpy requires no supporting OS subroutines.
Next: strcasestr—case-insensitive character string search, Previous: stpncpy—counted copy string returning a pointer to its end, Up: Strings and Memory (string.h) [Contents][Index]
strcasecmp—case-insensitive character string compareSynopsis
#include <strings.h> int strcasecmp(const char *a, const char *b);
Description
strcasecmp compares the string at a to
the string at b in a case-insensitive manner.
Returns
If *a sorts lexicographically after *b (after
both are converted to lowercase), strcasecmp returns a
number greater than zero. If the two strings match,
strcasecmp returns zero. If *a sorts
lexicographically before *b, strcasecmp returns a
number less than zero.
Portability
strcasecmp is in the Berkeley Software Distribution.
strcasecmp requires no supporting OS subroutines. It uses
tolower() from elsewhere in this library.
Next: strcat—concatenate strings, Previous: strcasecmp—case-insensitive character string compare, Up: Strings and Memory (string.h) [Contents][Index]
strcasestr—case-insensitive character string searchSynopsis
#include <string.h> char *strcasestr(const char *s, const char *find);
Description
strcasestr searchs the string s for
the first occurrence of the sequence find. strcasestr
is identical to strstr except the search is
case-insensitive.
Returns
A pointer to the first case-insensitive occurrence of the sequence
find or NULL if no match was found.
Portability
strcasestr is in the Berkeley Software Distribution.
strcasestr requires no supporting OS subroutines. It uses
tolower() from elsewhere in this library.
Next: strchr—search for character in string, Previous: strcasestr—case-insensitive character string search, Up: Strings and Memory (string.h) [Contents][Index]
strcat—concatenate stringsSynopsis
#include <string.h> char *strcat(char *restrict dst, const char *restrict src);
Description
strcat appends a copy of the string pointed to by src
(including the terminating null character) to the end of the
string pointed to by dst. The initial character of
src overwrites the null character at the end of dst.
Returns
This function returns the initial value of dst
Portability
strcat is ANSI C.
strcat requires no supporting OS subroutines.
Next: strchrnul—search for character in string, Previous: strcat—concatenate strings, Up: Strings and Memory (string.h) [Contents][Index]
strchr—search for character in stringSynopsis
#include <string.h> char * strchr(const char *string, int c);
Description
This function finds the first occurence of c (converted to
a char) in the string pointed to by string (including the
terminating null character).
Returns
Returns a pointer to the located character, or a null pointer
if c does not occur in string.
Portability
strchr is ANSI C.
strchr requires no supporting OS subroutines.
Next: strcmp—character string compare, Previous: strchr—search for character in string, Up: Strings and Memory (string.h) [Contents][Index]
strchrnul—search for character in stringSynopsis
#include <string.h> char * strchrnul(const char *string, int c);
Description
This function finds the first occurence of c (converted to
a char) in the string pointed to by string (including the
terminating null character).
Returns
Returns a pointer to the located character, or a pointer
to the concluding null byte if c does not occur in string.
Portability
strchrnul is a GNU extension.
strchrnul requires no supporting OS subroutines. It uses
strchr() and strlen() from elsewhere in this library.
Next: strcoll—locale-specific character string compare, Previous: strchrnul—search for character in string, Up: Strings and Memory (string.h) [Contents][Index]
strcmp—character string compareSynopsis
#include <string.h> int strcmp(const char *a, const char *b);
Description
strcmp compares the string at a to
the string at b.
Returns
If *a sorts lexicographically after *b,
strcmp returns a number greater than zero. If the two
strings match, strcmp returns zero. If *a
sorts lexicographically before *b, strcmp returns a
number less than zero.
Portability
strcmp is ANSI C.
strcmp requires no supporting OS subroutines.
Next: strcpy—copy string, Previous: strcmp—character string compare, Up: Strings and Memory (string.h) [Contents][Index]
strcoll—locale-specific character string compareSynopsis
#include <string.h> int strcoll(const char *stra, const char * strb);
Description
strcoll compares the string pointed to by stra to
the string pointed to by strb, using an interpretation
appropriate to the current LC_COLLATE state.
(NOT Cygwin:) The current implementation of strcoll simply
uses strcmp and does not support any language-specific sorting.
Returns
If the first string is greater than the second string,
strcoll returns a number greater than zero. If the two
strings are equivalent, strcoll returns zero. If the first
string is less than the second string, strcoll returns a
number less than zero.
Portability
strcoll is ANSI C.
strcoll requires no supporting OS subroutines.
Next: strcspn—count characters not in string, Previous: strcoll—locale-specific character string compare, Up: Strings and Memory (string.h) [Contents][Index]
strcpy—copy stringSynopsis
#include <string.h> char *strcpy(char *dst, const char *src);
Description
strcpy copies the string pointed to by src
(including the terminating null character) to the array
pointed to by dst.
Returns
This function returns the initial value of dst.
Portability
strcpy is ANSI C.
strcpy requires no supporting OS subroutines.
Next: strerror, strerror_l—convert error number to string, Previous: strcpy—copy string, Up: Strings and Memory (string.h) [Contents][Index]
strcspn—count characters not in stringSynopsis
size_t strcspn(const char *s1, const char *s2);
Description
This function computes the length of the initial part of
the string pointed to by s1 which consists entirely of
characters NOT from the string pointed to by s2
(excluding the terminating null character).
Returns
strcspn returns the length of the substring found.
Portability
strcspn is ANSI C.
strcspn requires no supporting OS subroutines.
Next: strerror_r—convert error number to string and copy to buffer, Previous: strcspn—count characters not in string, Up: Strings and Memory (string.h) [Contents][Index]
strerror, strerror_l—convert error number to stringSynopsis
#include <string.h>
char *strerror(int errnum);
char *strerror_l(int errnum, locale_t locale);
char *_strerror_r(struct _reent ptr, int errnum,
int internal, int *error);
Description
strerror converts the error number errnum into a
string. The value of errnum is usually a copy of errno.
If errnum is not a known error number, the result points to an
empty string.
strerror_l is like strerror but creates a string in a format
as expected in locale locale. If locale is LC_GLOBAL_LOCALE or
not a valid locale object, the behaviour is undefined.
This implementation of strerror prints out the following strings
for each of the values defined in ‘errno.h’:
0Success
E2BIGArg list too long
EACCESPermission denied
EADDRINUSEAddress already in use
EADDRNOTAVAILAddress not available
EADVAdvertise error
EAFNOSUPPORTAddress family not supported by protocol family
EAGAINNo more processes
EALREADYSocket already connected
EBADFBad file number
EBADMSGBad message
EBUSYDevice or resource busy
ECANCELEDOperation canceled
ECHILDNo children
ECOMMCommunication error
ECONNABORTEDSoftware caused connection abort
ECONNREFUSEDConnection refused
ECONNRESETConnection reset by peer
EDEADLKDeadlock
EDESTADDRREQDestination address required
EEXISTFile exists
EDOMMathematics argument out of domain of function
EFAULTBad address
EFBIGFile too large
EHOSTDOWNHost is down
EHOSTUNREACHHost is unreachable
EIDRMIdentifier removed
EILSEQIllegal byte sequence
EINPROGRESSConnection already in progress
EINTRInterrupted system call
EINVALInvalid argument
EIOI/O error
EISCONNSocket is already connected
EISDIRIs a directory
ELIBACCCannot access a needed shared library
ELIBBADAccessing a corrupted shared library
ELIBEXECCannot exec a shared library directly
ELIBMAXAttempting to link in more shared libraries than system limit
ELIBSCN.lib section in a.out corrupted
EMFILEFile descriptor value too large
EMLINKToo many links
EMSGSIZEMessage too long
EMULTIHOPMultihop attempted
ENAMETOOLONGFile or path name too long
ENETDOWNNetwork interface is not configured
ENETRESETConnection aborted by network
ENETUNREACHNetwork is unreachable
ENFILEToo many open files in system
ENOBUFSNo buffer space available
ENODATANo data
ENODEVNo such device
ENOENTNo such file or directory
ENOEXECExec format error
ENOLCKNo lock
ENOLINKVirtual circuit is gone
ENOMEMNot enough space
ENOMSGNo message of desired type
ENONETMachine is not on the network
ENOPKGNo package
ENOPROTOOPTProtocol not available
ENOSPCNo space left on device
ENOSRNo stream resources
ENOSTRNot a stream
ENOSYSFunction not implemented
ENOTBLKBlock device required
ENOTCONNSocket is not connected
ENOTDIRNot a directory
ENOTEMPTYDirectory not empty
ENOTRECOVERABLEState not recoverable
ENOTSOCKSocket operation on non-socket
ENOTSUPNot supported
ENOTTYNot a character device
ENXIONo such device or address
EOPNOTSUPPOperation not supported on socket
EOVERFLOWValue too large for defined data type
EOWNERDEADPrevious owner died
EPERMNot owner
EPIPEBroken pipe
EPROTOProtocol error
EPROTOTYPEProtocol wrong type for socket
EPROTONOSUPPORTUnknown protocol
ERANGEResult too large
EREMOTEResource is remote
EROFSRead-only file system
ESHUTDOWNCan’t send after socket shutdown
ESOCKTNOSUPPORTSocket type not supported
ESPIPEIllegal seek
ESRCHNo such process
ESRMNTSrmount error
ESTRPIPEStrings pipe error
ETIMEStream ioctl timeout
ETIMEDOUTConnection timed out
ETXTBSYText file busy
EWOULDBLOCKOperation would block (usually same as EAGAIN)
EXDEVCross-device link
_strerror_r is a reentrant version of the above.
Returns
This function returns a pointer to a string. Your application must
not modify that string.
Portability
ANSI C requires strerror, but does not specify the strings used
for each error number.
strerror_l is POSIX-1.2008.
Although this implementation of strerror is reentrant (depending
on _user_strerror), ANSI C declares that subsequent calls to
strerror may overwrite the result string; therefore portable
code cannot depend on the reentrancy of this subroutine.
Although this implementation of strerror guarantees a non-null
result with a NUL-terminator, some implementations return NULL
on failure. Although POSIX allows strerror to set errno
to EINVAL on failure, this implementation does not do so (unless
you provide _user_strerror).
POSIX recommends that unknown errnum result in a message
including that value, however it is not a requirement and this
implementation does not provide that information (unless you
provide _user_strerror).
This implementation of strerror provides for user-defined
extensibility. errno.h defines __ELASTERROR, which can be
used as a base for user-defined error values. If the user supplies a
routine named _user_strerror, and errnum passed to
strerror does not match any of the supported values,
_user_strerror is called with three arguments. The first is of
type int, and is the errnum value unknown to strerror.
The second is of type int, and matches the internal argument
of _strerror_r; this should be zero if called from strerror
and non-zero if called from any other function; _user_strerror can
use this information to satisfy the POSIX rule that no other
standardized function can overwrite a static buffer reused by
strerror. The third is of type int *, and matches the
error argument of _strerror_r; if a non-zero value is stored
into that location (usually EINVAL), then strerror will set
errno to that value, and the XPG variant of strerror_r will
return that value instead of zero or ERANGE. _user_strerror
returns a char * value; returning NULL implies that the user
function did not choose to handle errnum. The default
_user_strerror returns NULL for all input values. Note that
_user_sterror must be thread-safe, and only denote errors via the
third argument rather than modifying errno, if strerror and
strerror_r are are to comply with POSIX.
strerror requires no supporting OS subroutines.
Next: strlen—character string length, Previous: strerror, strerror_l—convert error number to string, Up: Strings and Memory (string.h) [Contents][Index]
strerror_r—convert error number to string and copy to bufferSynopsis
#include <string.h> #ifdef _GNU_SOURCE char *strerror_r(int errnum, char *buffer, size_t n); #else int strerror_r(int errnum, char *buffer, size_t n); #endif
Description
strerror_r converts the error number errnum into a
string and copies the result into the supplied buffer for
a length up to n, including the NUL terminator. The value of
errnum is usually a copy of errno. If errnum is not a known
error number, the result is the empty string.
See strerror for how strings are mapped to errnum.
Returns
There are two variants: the GNU version always returns a NUL-terminated
string, which is buffer if all went well, but which is another
pointer if n was too small (leaving buffer untouched). If the
return is not buffer, your application must not modify that string.
The POSIX version returns 0 on success, EINVAL if errnum was not
recognized, and ERANGE if n was too small. The variant chosen
depends on macros that you define before inclusion of string.h.
Portability
strerror_r with a char * result is a GNU extension.
strerror_r with an int result is required by POSIX 2001.
This function is compliant only if _user_strerror is not provided,
or if it is thread-safe and uses separate storage according to whether
the second argument of that function is non-zero. For more details
on _user_strerror, see the strerror documentation.
POSIX states that the contents of buf are unspecified on error, although this implementation guarantees a NUL-terminated string for all except n of 0.
POSIX recommends that unknown errnum result in a message including
that value, however it is not a requirement and this implementation
provides only an empty string (unless you provide _user_strerror).
POSIX also recommends that unknown errnum fail with EINVAL even
when providing such a message, however it is not a requirement and
this implementation will return success if _user_strerror provided
a non-empty alternate string without assigning into its third argument.
strerror_r requires no supporting OS subroutines.
Next: strlwr—force string to lowercase, Previous: strerror_r—convert error number to string and copy to buffer, Up: Strings and Memory (string.h) [Contents][Index]
strlen—character string lengthSynopsis
#include <string.h> size_t strlen(const char *str);
Description
The strlen function works out the length of the string
starting at *str by counting chararacters until it
reaches a NULL character.
Returns
strlen returns the character count.
Portability
strlen is ANSI C.
strlen requires no supporting OS subroutines.
Next: strncasecmp—case-insensitive character string compare, Previous: strlen—character string length, Up: Strings and Memory (string.h) [Contents][Index]
strlwr—force string to lowercaseSynopsis
#include <string.h> char *strlwr(char *a);
Description
strlwr converts each character in the string at a to
lowercase.
Returns
strlwr returns its argument, a.
Portability
strlwr is not widely portable.
strlwr requires no supporting OS subroutines.
Next: strncat—concatenate strings, Previous: strlwr—force string to lowercase, Up: Strings and Memory (string.h) [Contents][Index]
strncasecmp—case-insensitive character string compareSynopsis
#include <strings.h> int strncasecmp(const char *a, const char * b, size_t length);
Description
strncasecmp compares up to length characters
from the string at a to the string at b in a
case-insensitive manner.
Returns
If *a sorts lexicographically after *b (after
both are converted to lowercase), strncasecmp returns a
number greater than zero. If the two strings are equivalent,
strncasecmp returns zero. If *a sorts
lexicographically before *b, strncasecmp returns a
number less than zero.
Portability
strncasecmp is in the Berkeley Software Distribution.
strncasecmp requires no supporting OS subroutines. It uses
tolower() from elsewhere in this library.
Next: strncmp—character string compare, Previous: strncasecmp—case-insensitive character string compare, Up: Strings and Memory (string.h) [Contents][Index]
strncat—concatenate stringsSynopsis
#include <string.h>
char *strncat(char *restrict dst, const char *restrict src,
size_t length);
Description
strncat appends not more than length characters from
the string pointed to by src (including the terminating
null character) to the end of the string pointed to by
dst. The initial character of src overwrites the null
character at the end of dst. A terminating null character
is always appended to the result
Warnings
Note that a null is always appended, so that if the copy is
limited by the length argument, the number of characters
appended to dst is n + 1.
Returns
This function returns the initial value of dst
Portability
strncat is ANSI C.
strncat requires no supporting OS subroutines.
Next: strncpy—counted copy string, Previous: strncat—concatenate strings, Up: Strings and Memory (string.h) [Contents][Index]
strncmp—character string compareSynopsis
#include <string.h> int strncmp(const char *a, const char * b, size_t length);
Description
strncmp compares up to length characters
from the string at a to the string at b.
Returns
If *a sorts lexicographically after *b,
strncmp returns a number greater than zero. If the two
strings are equivalent, strncmp returns zero. If *a
sorts lexicographically before *b, strncmp returns a
number less than zero.
Portability
strncmp is ANSI C.
strncmp requires no supporting OS subroutines.
Next: strnstr—find string segment, Previous: strncmp—character string compare, Up: Strings and Memory (string.h) [Contents][Index]
strncpy—counted copy stringSynopsis
#include <string.h>
char *strncpy(char *restrict dst, const char *restrict src,
size_t length);
Description
strncpy copies not more than length characters from the
the string pointed to by src (including the terminating
null character) to the array pointed to by dst. If the
string pointed to by src is shorter than length
characters, null characters are appended to the destination
array until a total of length characters have been
written.
Returns
This function returns the initial value of dst.
Portability
strncpy is ANSI C.
strncpy requires no supporting OS subroutines.
Next: strnlen—character string length, Previous: strncpy—counted copy string, Up: Strings and Memory (string.h) [Contents][Index]
strnstr—find string segmentSynopsis
#include <string.h> size_t strnstr(const char *s1, const char *s2, size_t n);
Description
Locates the first occurrence in the string pointed to by s1 of
the sequence of limited to the n characters in the string
pointed to by s2
Returns
Returns a pointer to the located string segment, or a null
pointer if the string s2 is not found. If s2 points to
a string with zero length, s1 is returned.
Portability
strnstr is a BSD extension.
strnstr requires no supporting OS subroutines.
Next: strpbrk—find characters in string, Previous: strnstr—find string segment, Up: Strings and Memory (string.h) [Contents][Index]
strnlen—character string lengthSynopsis
#include <string.h> size_t strnlen(const char *str, size_t n);
Description
The strnlen function works out the length of the string
starting at *str by counting chararacters until it
reaches a NUL character or the maximum: n number of
characters have been inspected.
Returns
strnlen returns the character count or n.
Portability
strnlen is a GNU extension.
strnlen requires no supporting OS subroutines.
Next: strrchr—reverse search for character in string, Previous: strnlen—character string length, Up: Strings and Memory (string.h) [Contents][Index]
strpbrk—find characters in stringSynopsis
#include <string.h> char *strpbrk(const char *s1, const char *s2);
Description
This function locates the first occurence in the string
pointed to by s1 of any character in string pointed to by
s2 (excluding the terminating null character).
Returns
strpbrk returns a pointer to the character found in s1, or a
null pointer if no character from s2 occurs in s1.
Portability
strpbrk requires no supporting OS subroutines.
Next: strsignal—convert signal number to string, Previous: strpbrk—find characters in string, Up: Strings and Memory (string.h) [Contents][Index]
strrchr—reverse search for character in stringSynopsis
#include <string.h> char * strrchr(const char *string, int c);
Description
This function finds the last occurence of c (converted to
a char) in the string pointed to by string (including the
terminating null character).
Returns
Returns a pointer to the located character, or a null pointer
if c does not occur in string.
Portability
strrchr is ANSI C.
strrchr requires no supporting OS subroutines.
Next: strspn—find initial match, Previous: strrchr—reverse search for character in string, Up: Strings and Memory (string.h) [Contents][Index]
strsignal—convert signal number to stringSynopsis
#include <string.h> char *strsignal(int signal);
Description
strsignal converts the signal number signal into a
string. If signal is not a known signal number, the result
will be of the form "Unknown signal NN" where NN is the signal
is a decimal number.
Returns
This function returns a pointer to a string. Your application must
not modify that string.
Portability
POSIX.1-2008 C requires strsignal, but does not specify the strings used
for each signal number.
strsignal requires no supporting OS subroutines.
Next: strstr—find string segment, Previous: strsignal—convert signal number to string, Up: Strings and Memory (string.h) [Contents][Index]
strspn—find initial matchSynopsis
#include <string.h> size_t strspn(const char *s1, const char *s2);
Description
This function computes the length of the initial segment of
the string pointed to by s1 which consists entirely of
characters from the string pointed to by s2 (excluding the
terminating null character).
Returns
strspn returns the length of the segment found.
Portability
strspn is ANSI C.
strspn requires no supporting OS subroutines.
Next: strtok, strtok_r, strsep—get next token from a string, Previous: strspn—find initial match, Up: Strings and Memory (string.h) [Contents][Index]
strstr—find string segmentSynopsis
#include <string.h> char *strstr(const char *s1, const char *s2);
Description
Locates the first occurrence in the string pointed to by s1 of
the sequence of characters in the string pointed to by s2
(excluding the terminating null character).
Returns
Returns a pointer to the located string segment, or a null
pointer if the string s2 is not found. If s2 points to
a string with zero length, s1 is returned.
Portability
strstr is ANSI C.
strstr requires no supporting OS subroutines.
Next: strupr—force string to uppercase, Previous: strstr—find string segment, Up: Strings and Memory (string.h) [Contents][Index]
strtok, strtok_r, strsep—get next token from a stringSynopsis
#include <string.h>
char *strtok(char *restrict source,
const char *restrict delimiters);
char *strtok_r(char *restrict source,
const char *restrict delimiters,
char **lasts);
char *strsep(char **source_ptr, const char *delimiters);
Description
The strtok function is used to isolate sequential tokens in a
null-terminated string, *source. These tokens are delimited
in the string by at least one of the characters in *delimiters.
The first time that strtok is called, *source should be
specified; subsequent calls, wishing to obtain further tokens from
the same string, should pass a null pointer instead. The separator
string, *delimiters, must be supplied each time and may
change between calls.
The strtok function returns a pointer to the beginning of each
subsequent token in the string, after replacing the separator
character itself with a null character. When no more tokens remain,
a null pointer is returned.
The strtok_r function has the same behavior as strtok, except
a pointer to placeholder *lasts must be supplied by the caller.
The strsep function is similar in behavior to strtok, except
a pointer to the string pointer must be supplied source_ptr and
the function does not skip leading delimiters. When the string starts
with a delimiter, the delimiter is changed to the null character and
the empty string is returned. Like strtok_r and strtok, the
*source_ptr is updated to the next character following the
last delimiter found or NULL if the end of string is reached with
no more delimiters.
Returns
strtok, strtok_r, and strsep all return a pointer to the
next token, or NULL if no more tokens can be found. For
strsep, a token may be the empty string.
Notes
strtok is unsafe for multi-threaded applications. strtok_r
and strsep are thread-safe and should be used instead.
Portability
strtok is ANSI C.
strtok_r is POSIX.
strsep is a BSD extension.
strtok, strtok_r, and strsep require no supporting OS subroutines.
Next: strverscmp—version string compare, Previous: strtok, strtok_r, strsep—get next token from a string, Up: Strings and Memory (string.h) [Contents][Index]
strupr—force string to uppercaseSynopsis
#include <string.h> char *strupr(char *a);
Description
strupr converts each character in the string at a to
uppercase.
Returns
strupr returns its argument, a.
Portability
strupr is not widely portable.
strupr requires no supporting OS subroutines.
Next: strxfrm—transform string, Previous: strupr—force string to uppercase, Up: Strings and Memory (string.h) [Contents][Index]
strverscmp—version string compareSynopsis
#define _GNU_SOURCE #include <string.h> int strverscmp(const char *a, const char *b);
Description
strverscmp compares the string at a to
the string at b in a version-logical order.
Returns
If *a version-sorts after *b, strverscmp returns
a number greater than zero. If the two strings match, strverscmp
returns zero. If *a version-sorts before *b,
strverscmp returns a number less than zero.
Portability
strverscmp is a GNU extension.
strverscmp requires no supporting OS subroutines. It uses
isdigit() from elsewhere in this library.
Next: swab—swap adjacent bytes, Previous: strverscmp—version string compare, Up: Strings and Memory (string.h) [Contents][Index]
strxfrm—transform stringSynopsis
#include <string.h>
size_t strxfrm(char *restrict s1, const char *restrict s2,
size_t n);
Description
This function transforms the string pointed to by s2 and
places the resulting string into the array pointed to by
s1. The transformation is such that if the strcmp
function is applied to the two transformed strings, it returns
a value greater than, equal to, or less than zero,
correspoinding to the result of a strcoll function applied
to the same two original strings.
No more than n characters are placed into the resulting array pointed to by s1, including the terminating null character. If n is zero, s1 may be a null pointer. If copying takes place between objects that overlap, the behavior is undefined.
(NOT Cygwin:) The current implementation of strxfrm simply copies
the input and does not support any language-specific transformations.
Returns
The strxfrm function returns the length of the transformed string
(not including the terminating null character). If the value returned
is n or more, the contents of the array pointed to by
s1 are indeterminate.
Portability
strxfrm is ANSI C.
strxfrm requires no supporting OS subroutines.
Next: wcscasecmp—case-insensitive wide character string compare, Previous: strxfrm—transform string, Up: Strings and Memory (string.h) [Contents][Index]
swab—swap adjacent bytesSynopsis
#include <unistd.h> void swab(const void *in, void *out, ssize_t n);
Description
This function copies n bytes from the memory region
pointed to by in to the memory region pointed to by
out, exchanging adjacent even and odd bytes.
Portability
swab requires no supporting OS subroutines.
Next: wcsdup—wide character string duplicate, Previous: swab—swap adjacent bytes, Up: Strings and Memory (string.h) [Contents][Index]
wcscasecmp—case-insensitive wide character string compareSynopsis
#include <wchar.h> int wcscasecmp(const wchar_t *a, const wchar_t *b);
Description
wcscasecmp compares the wide character string at a to
the wide character string at b in a case-insensitive manner.
Returns
If *a sorts lexicographically after *b (after
both are converted to uppercase), wcscasecmp returns a
number greater than zero. If the two strings match,
wcscasecmp returns zero. If *a sorts
lexicographically before *b, wcscasecmp returns a
number less than zero.
Portability
POSIX-1.2008
wcscasecmp requires no supporting OS subroutines. It uses
tolower() from elsewhere in this library.
Next: wcsncasecmp—case-insensitive wide character string compare, Previous: wcscasecmp—case-insensitive wide character string compare, Up: Strings and Memory (string.h) [Contents][Index]
wcsdup—wide character string duplicateSynopsis
#include <wchar.h> wchar_t *wcsdup(const wchar_t *str); #include <wchar.h> wchar_t *_wcsdup_r(struct _reent *ptr, const wchar_t *str);
Description
wcsdup allocates a new wide character string using malloc,
and copies the content of the argument str into the newly
allocated string, thus making a copy of str.
Returns
wcsdup returns a pointer to the copy of str if enough
memory for the copy was available. Otherwise it returns NULL
and errno is set to ENOMEM.
Portability
POSIX-1.2008
Previous: wcsdup—wide character string duplicate, Up: Strings and Memory (string.h) [Contents][Index]
wcsncasecmp—case-insensitive wide character string compareSynopsis
#include <wchar.h> int wcsncasecmp(const wchar_t *a, const wchar_t * b, size_t length);
Description
wcsncasecmp compares up to length wide characters
from the string at a to the string at b in a
case-insensitive manner.
Returns
If *a sorts lexicographically after *b (after
both are converted to uppercase), wcsncasecmp returns a
number greater than zero. If the two strings are equivalent,
wcsncasecmp returns zero. If *a sorts
lexicographically before *b, wcsncasecmp returns a
number less than zero.
Portability
POSIX-1.2008
wcsncasecmp requires no supporting OS subroutines. It uses
tolower() from elsewhere in this library.
Next: Signal Handling (signal.h), Previous: Strings and Memory (string.h), Up: The Red Hat newlib C Library [Contents][Index]
This chapter describes wide-character string-handling functions and managing areas of memory containing wide characters. The corresponding declarations are in wchar.h.
wmemchr—find a wide character in memorywmemcmp—compare wide characters in memorywmemcpy—copy wide characters in memorywmemmove—copy wide characters in memory with overlapping areaswmempcpy—copy wide characters in memory and return end pointerwmemset—set wide characters in memorywcscat—concatenate two wide-character stringswcschr—wide-character string scanning operationwcscmp—compare two wide-character stringswcscoll—locale-specific wide-character string comparewcscpy—copy a wide-character stringwcpcpy—copy a wide-character string returning a pointer to its endwcscspn—get length of a complementary wide substringwcsftime—convert date and time to a formatted wide-character stringwcslcat—concatenate wide-character strings to specified lengthwcslcpy—copy a wide-character string to specified lengthwcslen—get wide-character string lengthwcsncat—concatenate part of two wide-character stringswcsncmp—compare part of two wide-character stringswcsncpy—copy part of a wide-character stringwcpncpy—copy part of a wide-character string returning a pointer to its endwcsnlen—get fixed-size wide-character string lengthwcspbrk—-scan wide-character string for a wide-character codewcsrchr—wide-character string scanning operationwcsspn—get length of a wide substringwcsstr—find a wide-character substringwcstok—get next token from a stringwcswidth—number of column positions of a wide-character stringwcsxfrm—locale-specific wide-character string transformationwcwidth—number of column positions of a wide-character code
Next: wmemcmp—compare wide characters in memory, Up: Wide Character Strings (wchar.h) [Contents][Index]
wmemchr—find a wide character in memorySynopsis
#include <wchar.h> wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);
Description
The wmemchr function locates the first occurrence of c in the
initial n wide characters of the object pointed to be s. This
function is not affected by locale and all wchar_t values are treated
identically. The null wide character and wchar_t values not
corresponding to valid characters are not treated specially.
If n is zero, s must be a valid pointer and the function behaves as if no valid occurrence of c is found.
Returns
The wmemchr function returns a pointer to the located
wide character, or a null pointer if the wide character does not occur
in the object.
Portability
wmemchr is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wmemcpy—copy wide characters in memory, Previous: wmemchr—find a wide character in memory, Up: Wide Character Strings (wchar.h) [Contents][Index]
wmemcmp—compare wide characters in memorySynopsis
#include <wchar.h> int wmemcmp(const wchar_t *s1, const wchar_t *s2, size_t n);
Description
The wmemcmp function compares the first n wide characters of the
object pointed to by s1 to the first n wide characters of the
object pointed to by s2. This function is not affected by locale
and all wchar_t values are treated identically. The null wide character
and wchar_t values not corresponding to valid characters are not treated
specially.
If n is zero, s1 and s2 must be a valid pointers and the function behaves as if the two objects compare equal.
Returns
The wmemcmp function returns an integer greater than, equal to,
or less than zero, accordingly as the object pointed to by s1 is
greater than, equal to, or less than the object pointed to by s2.
Portability
wmemcmp is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wmemmove—copy wide characters in memory with overlapping areas, Previous: wmemcmp—compare wide characters in memory, Up: Wide Character Strings (wchar.h) [Contents][Index]
wmemcpy—copy wide characters in memorySynopsis
#include <wchar.h>
wchar_t *wmemcpy(wchar_t *__restrict d,
const wchar_t *__restrict s, size_t n);
Description
The wmemcpy function copies n wide characters from the object
pointed to by s to the object pointed to be d. This function
is not affected by locale and all wchar_t values are treated
identically. The null wide character and wchar_t values not
corresponding to valid characters are not treated specially.
If n is zero, d and s must be a valid pointers, and the function copies zero wide characters.
Returns
The wmemcpy function returns the value of d.
Portability
wmemcpy is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wmempcpy—copy wide characters in memory and return end pointer, Previous: wmemcpy—copy wide characters in memory, Up: Wide Character Strings (wchar.h) [Contents][Index]
wmemmove—copy wide characters in memory with overlapping areasSynopsis
#include <wchar.h> wchar_t *wmemmove(wchar_t *d, const wchar_t *s, size_t n);
Description
The wmemmove function copies n wide characters from the object
pointed to by s to the object pointed to by d. Copying takes
place as if the n wide characters from the object pointed to by
s are first copied into a temporary array of n wide characters
that does not overlap the objects pointed to by d or s, and then
the n wide characters from the temporary array are copied into the
object pointed to by d.
This function is not affected by locale and all wchar_t values are treated identically. The null wide character and wchar_t values not corresponding to valid characters are not treated specially.
If n is zero, d and s must be a valid pointers, and the function copies zero wide characters.
Returns
The wmemmove function returns the value of d.
Portability
wmemmove is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wmemset—set wide characters in memory, Previous: wmemmove—copy wide characters in memory with overlapping areas, Up: Wide Character Strings (wchar.h) [Contents][Index]
wmempcpy—copy wide characters in memory and return end pointerSynopsis
#define _GNU_SOURCE
#include <wchar.h>
wchar_t *wmempcpy(wchar_t *d,
const wchar_t *s, size_t n);
Description
The wmemcpy function copies n wide characters from the object
pointed to by s to the object pointed to be d. This function
is not affected by locale and all wchar_t values are treated
identically. The null wide character and wchar_t values not
corresponding to valid characters are not treated specially.
If n is zero, d and s must be a valid pointers, and the function copies zero wide characters.
Returns
wmempcpy returns a pointer to the wide character following the
last wide character copied to the out region.
Portability
wmempcpy is a GNU extension.
No supporting OS subroutines are required.
Next: wcscat—concatenate two wide-character strings, Previous: wmempcpy—copy wide characters in memory and return end pointer, Up: Wide Character Strings (wchar.h) [Contents][Index]
wmemset—set wide characters in memorySynopsis
#include <wchar.h> wchar_t *wmemset(wchar_t *s, wchar_t c, size_t n);
Description
The wmemset function copies the value of c into each of the
first n wide characters of the object pointed to by s. This
function is not affected by locale and all wchar_t values are treated
identically. The null wide character and wchar_t values not
corresponding to valid characters are not treated specially.
If n is zero, s must be a valid pointer and the function copies zero wide characters.
Returns
The wmemset function returns the value of s.
Portability
wmemset is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcschr—wide-character string scanning operation, Previous: wmemset—set wide characters in memory, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcscat—concatenate two wide-character stringsSynopsis
#include <wchar.h>
wchar_t *wcscat(wchar_t *__restrict s1,
const wchar_t *__restrict s2);
Description
The wcscat function appends a copy of the wide-character string
pointed to by s2 (including the terminating null wide-character
code) to the end of the wide-character string pointed to by s1.
The initial wide-character code of s2 overwrites the null
wide-character code at the end of s1. If copying takes place between
objects that overlap, the behaviour is undefined.
Returns
The wcscat function returns s1;
no return value is reserved to indicate an error.
Portability
wcscat is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcscmp—compare two wide-character strings, Previous: wcscat—concatenate two wide-character strings, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcschr—wide-character string scanning operationSynopsis
#include <wchar.h> wchar_t *wcschr(const wchar_t *s, wchar_t c);
Description
The wcschr function locates the first occurrence of c in the
wide-character string pointed to by s. The value of c must be a
character representable as a type wchar_t and must be a wide-character
code corresponding to a valid character in the current locale.
The terminating null wide-character string.
Returns
Upon completion, wcschr returns a pointer to the wide-character
code, or a null pointer if the wide-character code is not found.
Portability
wcschr is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcscoll—locale-specific wide-character string compare, Previous: wcschr—wide-character string scanning operation, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcscmp—compare two wide-character stringsSynopsis
#include <wchar.h> int wcscmp(const wchar_t *s1, *s2);
Description
The wcscmp function compares the wide-character string pointed to
by s1 to the wide-character string pointed to by s2.
The sign of a non-zero return value is determined by the sign of the difference between the values of the first pair of wide-character codes that differ in the objects being compared.
Returns
Upon completion, wcscmp returns an integer greater than, equal to
or less than 0, if the wide-character string pointed to by s1 is
greater than, equal to or less than the wide-character string pointed
to by s2 respectively.
Portability
wcscmp is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcscpy—copy a wide-character string, Previous: wcscmp—compare two wide-character strings, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcscoll—locale-specific wide-character string compareSynopsis
#include <wchar.h> int wcscoll(const wchar_t *stra, const wchar_t * strb);
Description
wcscoll compares the wide-character string pointed to by
stra to the wide-character string pointed to by strb,
using an interpretation appropriate to the current LC_COLLATE
state.
(NOT Cygwin:) The current implementation of wcscoll simply
uses wcscmp and does not support any language-specific sorting.
Returns
If the first string is greater than the second string,
wcscoll returns a number greater than zero. If the two
strings are equivalent, wcscoll returns zero. If the first
string is less than the second string, wcscoll returns a
number less than zero.
Portability
wcscoll is ISO/IEC 9899/AMD1:1995 (ISO C).
Next: wcpcpy—copy a wide-character string returning a pointer to its end, Previous: wcscoll—locale-specific wide-character string compare, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcscpy—copy a wide-character stringSynopsis
#include <wchar.h>
wchar_t *wcscpy(wchar_t *__restrict s1,
const wchar_t *__restrict s2);
Description
The wcscpy function copies the wide-character string pointed to by
s2 (including the terminating null wide-character code) into the
array pointed to by s1. If copying takes place between objects that
overlap, the behaviour is undefined.
Returns
The wcscpy function returns s1; no return value is reserved to
indicate an error.
Portability
wcscpy is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcscspn—get length of a complementary wide substring, Previous: wcscpy—copy a wide-character string, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcpcpy—copy a wide-character string returning a pointer to its endSynopsis
#include <wchar.h> wchar_t *wcpcpy(wchar_t *s1, const wchar_t *s2);
Description
The wcpcpy function copies the wide-character string pointed to by
s2 (including the terminating null wide-character code) into the
array pointed to by s1. If copying takes place between objects that
overlap, the behaviour is undefined.
Returns
This function returns a pointer to the end of the destination string,
thus pointing to the trailing ’\0’.
Portability
wcpcpy is a GNU extension.
No supporting OS subroutines are required.
Next: wcsftime—convert date and time to a formatted wide-character string, Previous: wcpcpy—copy a wide-character string returning a pointer to its end, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcscspn—get length of a complementary wide substringSynopsis
#include <wchar.h> size_t wcscspn(const wchar_t *s, wchar_t *set);
Description
The wcscspn function computes the length of the maximum initial
segment of the wide-character string pointed to by s which consists
entirely of wide-character codes not from the wide-character string
pointed to by set.
Returns
The wcscspn function returns the length of the initial substring of
s1; no return value is reserved to indicate an error.
Portability
wcscspn is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcslcat—concatenate wide-character strings to specified length, Previous: wcscspn—get length of a complementary wide substring, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsftime—convert date and time to a formatted wide-character stringSynopsis
#include <time.h>
#include <wchar.h>
size_t wcsftime(wchar_t *s, size_t maxsize,
const wchar_t *format, const struct tm *timp);
Description
wcsftime is equivalent to strftime, except that:
(The difference in all of the above being wide characters versus regular
characters.)
See strftime for the details of the format specifiers.
Returns
When the formatted time takes up no more than maxsize wide characters,
the result is the length of the formatted wide string. Otherwise, if the
formatting operation was abandoned due to lack of room, the result is
0, and the wide-character string starting at s corresponds to just those
parts of *format that could be completely filled in within the
maxsize limit.
Portability
C99 and POSIX require wcsftime, but do not specify the contents of
*s when the formatted string would require more than
maxsize characters. Unrecognized specifiers and fields of
timp that are out of range cause undefined results. Since some
formats expand to 0 bytes, it is wise to set *s to a nonzero
value beforehand to distinguish between failure and an empty string.
This implementation does not support s being NULL, nor overlapping
s and format.
wcsftime requires no supporting OS subroutines.
See Also
strftime
Next: wcslcpy—copy a wide-character string to specified length, Previous: wcsftime—convert date and time to a formatted wide-character string, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcslcat—concatenate wide-character strings to specified lengthSynopsis
#include <wchar.h> size_t wcslcat(wchar_t *dst, const wchar_t *src, size_t siz);
Description
The wcslcat function appends wide characters from src to
end of the dst wide-character string so that the resultant
wide-character string is not more than siz wide characters
including the terminating null wide-character code. A terminating
null wide character is always added unless siz is 0. Thus,
the maximum number of wide characters that can be appended from
src is siz - 1. If copying takes place between objects
that overlap, the behaviour is undefined.
Returns
Wide-character string length of initial dst plus the
wide-character string length of src (does not include
terminating null wide-characters). If the return value is
greater than or equal to siz, then truncation occurred and
not all wide characters from src were appended.
Portability
No supporting OS subroutines are required.
Next: wcslen—get wide-character string length, Previous: wcslcat—concatenate wide-character strings to specified length, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcslcpy—copy a wide-character string to specified lengthSynopsis
#include <wchar.h> size_t wcslcpy(wchar_t *dst, const wchar_t *src, size_t siz);
Description
wcslcpy copies wide characters from src to dst
such that up to siz - 1 characters are copied. A
terminating null is appended to the result, unless siz
is zero.
Returns
wcslcpy returns the number of wide characters in src,
not including the terminating null wide character. If the
return value is greater than or equal to siz, then
not all wide characters were copied from src and truncation
occurred.
Portability
No supporting OS subroutines are required.
Next: wcsncat—concatenate part of two wide-character strings, Previous: wcslcpy—copy a wide-character string to specified length, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcslen—get wide-character string lengthSynopsis
#include <wchar.h> size_t wcslen(const wchar_t *s);
Description
The wcslen function computes the number of wide-character codes
in the wide-character string to which s points, not including the
terminating null wide-character code.
Returns
The wcslen function returns the length of s; no return value is
reserved to indicate an error.
Portability
wcslen is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcsncmp—compare part of two wide-character strings, Previous: wcslen—get wide-character string length, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsncat—concatenate part of two wide-character stringsSynopsis
#include <wchar.h>
wchar_t *wcsncat(wchar_t *__restrict s1,
const wchar_t *__restrict s2, size_t n);
Description
The wcsncat function appends not more than n wide-character
codes (a null wide-character code and wide-character codes that follow
it are not appended) from the array pointed to by s2 to the end of
the wide-character string pointed to by s1. The initial
wide-character code of s2 overwrites the null wide-character code
at the end of s1.
A terminating null wide-character code is always appended to the result.
If copying takes place between objects that overlap, the behaviour is
undefined.
Returns
The wcsncat function returns s1; no return value is reserved to
indicate an error.
Portability
wcsncat is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcsncpy—copy part of a wide-character string, Previous: wcsncat—concatenate part of two wide-character strings, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsncmp—compare part of two wide-character stringsSynopsis
#include <wchar.h> int wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n);
Description
The wcsncmp function compares not more than n wide-character
codes (wide-character codes that follow a null wide-character code are
not compared) from the array pointed to by s1 to the array pointed
to by s2.
The sign of a non-zero return value is determined by the sign of the difference between the values of the first pair of wide-character codes that differ in the objects being compared.
Returns
Upon successful completion, wcsncmp returns an integer greater than,
equal to or less than 0, if the possibly null-terminated array pointed
to by s1 is greater than, equal to or less than the possibly
null-terminated array pointed to by s2 respectively.
Portability
wcsncmp is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcpncpy—copy part of a wide-character string returning a pointer to its end, Previous: wcsncmp—compare part of two wide-character strings, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsncpy—copy part of a wide-character stringSynopsis
#include <wchar.h>
wchar_t *wcsncpy(wchar_t *__restrict s1,
const wchar_t *__restrict s2, size_t n);
Description
The wcsncpy function copies not more than n wide-character codes
(wide-character codes that follow a null wide-character code are not
copied) from the array pointed to by s2 to the array pointed to
by s1. If copying takes place between objects that overlap, the
behaviour is undefined. Note that if s1 contains more than n
wide characters before its terminating null, the result is not
null-terminated.
If the array pointed to by s2 is a wide-character string that is shorter than n wide-character codes, null wide-character codes are appended to the copy in the array pointed to by s1, until n wide-character codes in all are written.
Returns
The wcsncpy function returns s1; no return value is reserved to
indicate an error.
Portability
ISO/IEC 9899; POSIX.1.
No supporting OS subroutines are required.
Next: wcsnlen—get fixed-size wide-character string length, Previous: wcsncpy—copy part of a wide-character string, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcpncpy—copy part of a wide-character string returning a pointer to its endSynopsis
#include <wchar.h>
wchar_t *wcpncpy(wchar_t *__restrict s1,
const wchar_t *__restrict s2, size_t n);
Description
The wcpncpy function copies not more than n wide-character codes
(wide-character codes that follow a null wide-character code are not
copied) from the array pointed to by s2 to the array pointed to
by s1. If copying takes place between objects that overlap, the
behaviour is undefined.
If the array pointed to by s2 is a wide-character string that is shorter than n wide-character codes, null wide-character codes are appended to the copy in the array pointed to by s1, until n wide-character codes in all are written.
Returns
The wcpncpy function returns s1; no return value is reserved to
indicate an error.
Portability
wcpncpy is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcspbrk—-scan wide-character string for a wide-character code, Previous: wcpncpy—copy part of a wide-character string returning a pointer to its end, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsnlen—get fixed-size wide-character string lengthSynopsis
#include <wchar.h> size_t wcsnlen(const wchar_t *s, size_t maxlen);
Description
The wcsnlen function computes the number of wide-character codes
in the wide-character string pointed to by s not including the
terminating L’\0’ wide character but at most maxlen wide
characters.
Returns
wcsnlen returns the length of s if it is less then maxlen,
or maxlen if there is no L’\0’ wide character in first maxlen
characters.
Portability
wcsnlen is a GNU extension.
wcsnlen requires no supporting OS subroutines.
Next: wcsrchr—wide-character string scanning operation, Previous: wcsnlen—get fixed-size wide-character string length, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcspbrk—-scan wide-character string for a wide-character codeSynopsis
#include <wchar.h> wchar_t *wcspbrk(const wchar_t *s, const wchar_t *set);
Description
The wcspbrk function locates the first occurrence in the
wide-character string pointed to by s of any wide-character code
from the wide-character string pointed to by set.
Returns
Upon successful completion, wcspbrk returns a pointer to the
wide-character code or a null pointer if no wide-character code from
set occurs in s.
Portability
wcspbrk is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcsspn—get length of a wide substring, Previous: wcspbrk—-scan wide-character string for a wide-character code, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsrchr—wide-character string scanning operationSynopsis
#include <wchar.h> wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
Description
The wcsrchr function locates the last occurrence of c in the
wide-character string pointed to by s. The value of c must be a
character representable as a type wchar_t and must be a wide-character
code corresponding to a valid character in the current locale.
The terminating null wide-character code is considered to be part of
the wide-character string.
Returns
Upon successful completion, wcsrchr returns a pointer to the
wide-character code or a null pointer if c does not occur in the
wide-character string.
Portability
wcsrchr is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcsstr—find a wide-character substring, Previous: wcsrchr—wide-character string scanning operation, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsspn—get length of a wide substringSynopsis
#include <wchar.h> size_t wcsspn(const wchar_t *s, const wchar_t *set);
Description
The wcsspn function computes the length of the maximum initial
segment of the wide-character string pointed to by s which consists
entirely of wide-character codes from the wide-character string
pointed to by set.
Returns
The wcsspn() function returns the length s1; no return value is
reserved to indicate an error.
Portability
wcsspn is ISO/IEC 9899/AMD1:1995 (ISO C).
No supporting OS subroutines are required.
Next: wcstok—get next token from a string, Previous: wcsspn—get length of a wide substring, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsstr—find a wide-character substringSynopsis
#include <wchar.h>
wchar_t *wcsstr(const wchar_t *__restrict big,
const wchar_t *__restrict little);
Description
The wcsstr function locates the first occurrence in the
wide-character string pointed to by big of the sequence of
wide characters (excluding the terminating null wide character) in the
wide-character string pointed to by little.
Returns
On successful completion, wcsstr returns a pointer to the located
wide-character string, or a null pointer if the wide-character string
is not found.
If little points to a wide-character string with zero length, the function returns big.
Portability
wcsstr is ISO/IEC 9899/AMD1:1995 (ISO C).
Next: wcswidth—number of column positions of a wide-character string, Previous: wcsstr—find a wide-character substring, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcstok—get next token from a stringSynopsis
#include <wchar.h>
wchar_t *wcstok(wchar_t *__restrict source,
const wchar_t *__restrict delimiters,
wchar_t **__restrict lasts);
Description
The wcstok function is the wide-character equivalent of the
strtok_r function (which in turn is the same as the strtok
function with an added argument to make it thread-safe).
The wcstok function is used to isolate (one at a time)
sequential tokens in a null-terminated wide-character string,
*source. A token is defined as a substring not containing
any wide-characters from *delimiters.
The first time that wcstok is called, *source should
be specified with the wide-character string to be searched, and
*lasts–but not lasts, which must be non-NULL–may be
random; subsequent calls, wishing to obtain further tokens from
the same string, should pass a null pointer for *source
instead but must supply *lasts unchanged from the last
call. The separator wide-character string, *delimiters,
must be supplied each time and may change between calls.
A pointer to placeholder *lasts must be supplied by
the caller, and is set each time as needed to save the state
by wcstok. Every call to wcstok with *source
== NULL must pass the value of *lasts as last set
by wcstok.
The wcstok function returns a pointer to the beginning of each
subsequent token in the string, after replacing the separator
wide-character itself with a null wide-character. When no more tokens
remain, a null pointer is returned.
Returns
wcstok returns a pointer to the first wide character of a token, or
NULL if there is no token.
Notes
wcstok is thread-safe (unlike strtok, but like strtok_r).
wcstok writes into the string being searched.
Portability
wcstok is C99 and POSIX.1-2001.
wcstok requires no supporting OS subroutines.
Next: wcsxfrm—locale-specific wide-character string transformation, Previous: wcstok—get next token from a string, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcswidth—number of column positions of a wide-character stringSynopsis
#include <wchar.h> int wcswidth(const wchar_t *pwcs, size_t n);
Description
The wcswidth function shall determine the number of column
positions required for n wide-character codes (or fewer than n
wide-character codes if a null wide-character code is encountered
before n wide-character codes are exhausted) in the string pointed
to by pwcs.
Returns
The wcswidth function either shall return 0 (if pwcs points to a
null wide-character code), or return the number of column positions
to be occupied by the wide-character string pointed to by pwcs, or
return -1 (if any of the first n wide-character codes in the
wide-character string pointed to by pwcs is not a printable
wide-character code).
Portability
wcswidth has been introduced in the Single UNIX Specification Volume 2.
wcswidth has been marked as an extension in the Single UNIX Specification Volume 3.
Next: wcwidth—number of column positions of a wide-character code, Previous: wcswidth—number of column positions of a wide-character string, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcsxfrm—locale-specific wide-character string transformationSynopsis
#include <wchar.h>
int wcsxfrm(wchar_t *__restrict stra,
const wchar_t *__restrict strb, size_t n);
Description
wcsxfrm transforms the wide-character string pointed to by
strb to the wide-character string pointed to by stra,
Comparing two transformed wide strings with wcscmp should return
the same result as comparing the original strings with wcscoll.
No more than n wide characters are transformed, including the
trailing null character.
If n is 0, stra may be a NULL pointer.
(NOT Cygwin:) The current implementation of wcsxfrm simply uses
wcslcpy and does not support any language-specific transformations.
Returns
wcsxfrm returns the length of the transformed wide character
string. if the return value is greater or equal to n, the
content of stra is undefined.
Portability
wcsxfrm is ISO/IEC 9899/AMD1:1995 (ISO C).
Previous: wcsxfrm—locale-specific wide-character string transformation, Up: Wide Character Strings (wchar.h) [Contents][Index]
wcwidth—number of column positions of a wide-character codeSynopsis
#include <wchar.h> int wcwidth(const wint_t wc);
Description
The wcwidth function shall determine the number of column
positions required for the wide character wc. The application
shall ensure that the value of wc is a character representable
as a wint_t (combining Unicode surrogate pairs into single 21-bit
Unicode code points), and is a wide-character code corresponding to a
valid character in the current locale.
Returns
The wcwidth function shall either return 0 (if wc is a null
wide-character code), or return the number of column positions to
be occupied by the wide-character code wc, or return -1 (if wc
does not correspond to a printable wide-character code).
Portability
wcwidth has been introduced in the Single UNIX Specification Volume 2.
wcwidth has been marked as an extension in the Single UNIX Specification Volume 3.
Next: Time Functions (time.h), Previous: Wide Character Strings (wchar.h), Up: The Red Hat newlib C Library [Contents][Index]
A signal is an event that interrupts the normal flow of control in your program. Your operating environment normally defines the full set of signals available (see sys/signal.h), as well as the default means of dealing with them—typically, either printing an error message and aborting your program, or ignoring the signal.
All systems support at least the following signals:
SIGABRTAbnormal termination of a program; raised by the abort function.
SIGFPEA domain error in arithmetic, such as overflow, or division by zero.
SIGILLAttempt to execute as a function data that is not executable.
SIGINTInterrupt; an interactive attention signal.
SIGSEGVAn attempt to access a memory location that is not available.
SIGTERMA request that your program end execution.
Two functions are available for dealing with asynchronous signals—one to allow your program to send signals to itself (this is called raising a signal), and one to specify subroutines (called handlers to handle particular signals that you anticipate may occur—whether raised by your own program or the operating environment.
To support these functions, signal.h defines three macros:
SIG_DFLUsed with the signal function in place of a pointer to a
handler subroutine, to select the operating environment’s default
handling of a signal.
SIG_IGNUsed with the signal function in place of a pointer to a
handler, to ignore a particular signal.
SIG_ERRReturned by the signal function in place of a pointer to a
handler, to indicate that your request to set up a handler could not
be honored for some reason.
signal.h also defines an integral type, sig_atomic_t.
This type is not used in any function declarations; it exists only to
allow your signal handlers to declare a static storage location where
they may store a signal value. (Static storage is not otherwise
reliable from signal handlers.)
psignal—print a signal message on standard errorraise—send a signalsig2str, str2sig—Translate between signal number and namesignal—specify handler subroutine for a signal
Next: raise—send a signal, Up: Signal Handling (signal.h) [Contents][Index]
psignal—print a signal message on standard errorSynopsis
#include <stdio.h> void psignal(int signal, const char *prefix);
Description
Use psignal to print (on standard error) a signal message
corresponding to the value of the signal number signal.
Unless you use NULL as the value of the argument prefix, the
signal message will begin with the string at prefix, followed by a
colon and a space (: ). The remainder of the signal message is one
of the strings described for strsignal.
Returns
psignal returns no result.
Portability
POSIX.1-2008 requires psignal, but the strings issued vary from one
implementation to another.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.
Next: sig2str, str2sig—Translate between signal number and name, Previous: psignal—print a signal message on standard error, Up: Signal Handling (signal.h) [Contents][Index]
raise—send a signalSynopsis
#include <signal.h> int raise(int sig); int _raise_r(void *reent, int sig);
Description
Send the signal sig (one of the macros from ‘sys/signal.h’).
This interrupts your program’s normal flow of execution, and allows a signal
handler (if you’ve defined one, using signal) to take control.
The alternate function _raise_r is a reentrant version. The extra
argument reent is a pointer to a reentrancy structure.
Returns
The result is 0 if sig was successfully raised, 1
otherwise. However, the return value (since it depends on the normal
flow of execution) may not be visible, unless the signal handler for
sig terminates with a return or unless SIG_IGN is in
effect for this signal.
Portability
ANSI C requires raise, but allows the full set of signal numbers
to vary from one implementation to another.
Required OS subroutines: getpid, kill.
Next: signal—specify handler subroutine for a signal, Previous: raise—send a signal, Up: Signal Handling (signal.h) [Contents][Index]
sig2str, str2sig—Translate between signal number and nameSynopsis
#include <signal.h> int sig2str(int signum, char *str); int str2sig(const char *restrict str, int *restrict pnum);
Description
The sig2str function translates the signal number specified by signum to
a signal name and stores this string in the location specified by str. The
application must ensure that str points to a location that can store the
string including the terminating null byte. The symbolic constant
SIG2STR_MAX defined in ‘signal.h’ gives the maximum number of bytes
required.
The str2sig function translates the signal name in the string pointed to by
str to a signal number and stores this value in the location specified by
pnum.
Returns
sig2str returns 0 if signum> is a valid, supported signal number.
Otherwise, it returns -1.
str2sig returns 0 if it stores a value in the location pointed to by
pnum. Otherwise it returns -1.
Previous: sig2str, str2sig—Translate between signal number and name, Up: Signal Handling (signal.h) [Contents][Index]
signal—specify handler subroutine for a signalSynopsis
#include <signal.h> void (*signal(int sig, void(*func)(int))) (int); void (*_signal_r(void *reent, int sig, void(*func)(int))) (int);
Description
signal provides a simple signal-handling implementation for embedded
targets.
signal allows you to request changed treatment for a particular
signal sig. You can use one of the predefined macros SIG_DFL
(select system default handling) or SIG_IGN (ignore this signal)
as the value of func; otherwise, func is a function pointer
that identifies a subroutine in your program as the handler for this signal.
Some of the execution environment for signal handlers is
unpredictable; notably, the only library function required to work
correctly from within a signal handler is signal itself, and
only when used to redefine the handler for the current signal value.
Static storage is likewise unreliable for signal handlers, with one
exception: if you declare a static storage location as ‘volatile
sig_atomic_t’, then you may use that location in a signal handler to
store signal values.
If your signal handler terminates using return (or implicit
return), your program’s execution continues at the point
where it was when the signal was raised (whether by your program
itself, or by an external event). Signal handlers can also
use functions such as exit and abort to avoid returning.
The alternate function _signal_r is the reentrant version.
The extra argument reent is a pointer to a reentrancy structure.
Returns
If your request for a signal handler cannot be honored, the result is
SIG_ERR; a specific error number is also recorded in errno.
Otherwise, the result is the previous handler (a function pointer or one of the predefined macros).
Portability
ANSI C requires signal.
No supporting OS subroutines are required to link with signal, but
it will not have any useful effects, except for software generated signals,
without an operating system that can actually raise exceptions.
Next: Locale (locale.h), Previous: Signal Handling (signal.h), Up: The Red Hat newlib C Library [Contents][Index]
This chapter groups functions used either for reporting on time (elapsed, current, or compute time) or to perform calculations based on time.
The header file time.h defines three types. clock_t and
time_t are both used for representations of time particularly
suitable for arithmetic. (In this implementation, quantities of type
clock_t have the highest resolution possible on your machine,
and quantities of type time_t resolve to seconds.) size_t
is also defined if necessary for quantities representing sizes.
time.h also defines the structure tm for the traditional
representation of Gregorian calendar time as a series of numbers, with
the following fields:
tm_secSeconds, between 0 and 60 inclusive (60 allows for leap seconds).
tm_minMinutes, between 0 and 59 inclusive.
tm_hourHours, between 0 and 23 inclusive.
tm_mdayDay of the month, between 1 and 31 inclusive.
tm_monMonth, between 0 (January) and 11 (December).
tm_yearYear (since 1900), can be negative for earlier years.
tm_wdayDay of week, between 0 (Sunday) and 6 (Saturday).
tm_ydayNumber of days elapsed since last January 1, between 0 and 365 inclusive.
tm_isdstDaylight Savings Time flag: positive means DST in effect, zero means DST not in effect, negative means no information about DST is available. Although for mktime(), negative means that it should decide if DST is in effect or not.
asctime—format time as stringclock—cumulative processor timectime—convert time to local and format as stringdifftime—subtract two timesgmtime—convert time to UTC traditional formlocaltime—convert time to local representationmktime—convert time to arithmetic representationstrftime, strftime_l—convert date and time to a formatted stringtime—get current calendar time (as single number)__tz_lock, __tz_unlock—lock time zone global variablestzset—set timezone characteristics from TZ environment variable
Next: clock—cumulative processor time, Up: Time Functions (time.h) [Contents][Index]
asctime—format time as stringSynopsis
#include <time.h> char *asctime(const struct tm *clock); char *_asctime_r(const struct tm *clock, char *buf);
Description
Format the time value at clock into a string of the form
Wed Jun 15 11:38:07 1988\n\0
The string is generated in a static buffer; each call to asctime
overwrites the string generated by previous calls.
Returns
A pointer to the string containing a formatted timestamp.
Portability
ANSI C requires asctime.
asctime requires no supporting OS subroutines.
Next: ctime—convert time to local and format as string, Previous: asctime—format time as string, Up: Time Functions (time.h) [Contents][Index]
clock—cumulative processor timeSynopsis
#include <time.h> clock_t clock(void);
Description
Calculates the best available approximation of the cumulative amount
of time used by your program since it started. To convert the result
into seconds, divide by the macro CLOCKS_PER_SEC.
Returns
The amount of processor time used so far by your program, in units
defined by the machine-dependent macro CLOCKS_PER_SEC. If no
measurement is available, the result is (clock_t)-1.
Portability
ANSI C requires clock and CLOCKS_PER_SEC.
Supporting OS subroutine required: times.
Next: difftime—subtract two times, Previous: clock—cumulative processor time, Up: Time Functions (time.h) [Contents][Index]
ctime—convert time to local and format as stringSynopsis
#include <time.h> char *ctime(const time_t *clock); char *ctime_r(const time_t *clock, char *buf);
Description
Convert the time value at clock to local time (like localtime)
and format it into a string of the form
Wed Jun 15 11:38:07 1988\n\0
(like asctime).
Returns
A pointer to the string containing a formatted timestamp.
Portability
ANSI C requires ctime.
ctime requires no supporting OS subroutines.
Next: gmtime—convert time to UTC traditional form, Previous: ctime—convert time to local and format as string, Up: Time Functions (time.h) [Contents][Index]
difftime—subtract two timesSynopsis
#include <time.h> double difftime(time_t tim1, time_t tim2);
Description
Subtracts the two times in the arguments: ‘tim1 - tim2’.
Returns
The difference (in seconds) between tim2 and tim1, as a double.
Portability
ANSI C requires difftime, and defines its result to be in seconds
in all implementations.
difftime requires no supporting OS subroutines.
Next: localtime—convert time to local representation, Previous: difftime—subtract two times, Up: Time Functions (time.h) [Contents][Index]
gmtime—convert time to UTC traditional formSynopsis
#include <time.h> struct tm *gmtime(const time_t *clock); struct tm *gmtime_r(const time_t *clock, struct tm *res);
Description
gmtime takes the time at clock representing the number
of elapsed seconds since 00:00:00 on January 1, 1970, Universal
Coordinated Time (UTC, also known in some countries as GMT,
Greenwich Mean time) and converts it to a struct tm
representation.
gmtime constructs the traditional time representation in static
storage; each call to gmtime or localtime will overwrite the
information generated by previous calls to either function.
Returns
A pointer to the traditional time representation (struct tm).
Portability
ANSI C requires gmtime.
gmtime requires no supporting OS subroutines.
Next: mktime—convert time to arithmetic representation, Previous: gmtime—convert time to UTC traditional form, Up: Time Functions (time.h) [Contents][Index]
localtime—convert time to local representationSynopsis
#include <time.h> struct tm *localtime(time_t *clock); struct tm *localtime_r(time_t *clock, struct tm *res);
Description
localtime converts the time at clock into local time, then
converts its representation from the arithmetic representation to the
traditional representation defined by struct tm.
localtime constructs the traditional time representation in static
storage; each call to gmtime or localtime will overwrite the
information generated by previous calls to either function.
mktime is the inverse of localtime.
Returns
A pointer to the traditional time representation (struct tm).
Portability
ANSI C requires localtime.
localtime requires no supporting OS subroutines.
Next: strftime, strftime_l—convert date and time to a formatted string, Previous: localtime—convert time to local representation, Up: Time Functions (time.h) [Contents][Index]
mktime—convert time to arithmetic representationSynopsis
#include <time.h> time_t mktime(struct tm *timp);
Description
mktime assumes the time at timp is a local time, and converts
its representation from the traditional representation defined by
struct tm into a representation suitable for arithmetic.
localtime is the inverse of mktime.
Returns
If the contents of the structure at timp do not form a valid
calendar time representation, the result is -1. Otherwise, the
result is the time, converted to a time_t value.
Portability
ANSI C requires mktime.
mktime requires no supporting OS subroutines.
Next: time—get current calendar time (as single number), Previous: mktime—convert time to arithmetic representation, Up: Time Functions (time.h) [Contents][Index]
strftime, strftime_l—convert date and time to a formatted stringSynopsis
#include <time.h>
size_t strftime(char *restrict s, size_t maxsize,
const char *restrict format,
const struct tm *restrict timp);
size_t strftime_l(char *restrict s, size_t maxsize,
const char *restrict format,
const struct tm *restrict timp,
locale_t locale);
Description
strftime converts a struct tm representation of the time (at
timp) into a null-terminated string, starting at s and occupying
no more than maxsize characters.
strftime_l is like strftime but creates a string in a format
as expected in locale locale. If locale is LC_GLOBAL_LOCALE or
not a valid locale object, the behaviour is undefined.
You control the format of the output using the string at format.
*format can contain two kinds of specifications: text to be
copied literally into the formatted string, and time conversion
specifications. Time conversion specifications are two- and
three-character sequences beginning with ‘%’ (use ‘%%’ to
include a percent sign in the output). Each defined conversion
specification selects only the specified field(s) of calendar time
data from *timp, and converts it to a string in one of the
following ways:
%aThe abbreviated weekday name according to the current locale. [tm_wday]
%AThe full weekday name according to the current locale.
In the default "C" locale, one of ‘Sunday’, ‘Monday’, ‘Tuesday’,
‘Wednesday’, ‘Thursday’, ‘Friday’, ‘Saturday’. [tm_wday]
%bThe abbreviated month name according to the current locale. [tm_mon]
%BThe full month name according to the current locale.
In the default "C" locale, one of ‘January’, ‘February’,
‘March’, ‘April’, ‘May’, ‘June’, ‘July’,
‘August’, ‘September’, ‘October’, ‘November’,
‘December’. [tm_mon]
%cThe preferred date and time representation for the current locale. [tm_sec, tm_min, tm_hour, tm_mday, tm_mon, tm_year, tm_wday]
%CThe century, that is, the year divided by 100 then truncated. For
4-digit years, the result is zero-padded and exactly two characters;
but for other years, there may a negative sign or more digits. In
this way, ‘%C%y’ is equivalent to ‘%Y’. [tm_year]
%dThe day of the month, formatted with two digits (from ‘01’ to
‘31’). [tm_mday]
%DA string representing the date, in the form ‘"%m/%d/%y"’.
[tm_mday, tm_mon, tm_year]
%eThe day of the month, formatted with leading space if single digit
(from ‘1’ to ‘31’). [tm_mday]
%ExIn some locales, the E modifier selects alternative representations of
certain modifiers x. In newlib, it is ignored, and treated as %x.
%FA string representing the ISO 8601:2000 date format, in the form
‘"%Y-%m-%d"’. [tm_mday, tm_mon, tm_year]
%gThe last two digits of the week-based year, see specifier %G (from
‘00’ to ‘99’). [tm_year, tm_wday, tm_yday]
%GThe week-based year. In the ISO 8601:2000 calendar, week 1 of the year includes January 4th, and begin on Mondays. Therefore, if January 1st, 2nd, or 3rd falls on a Sunday, that day and earlier belong to the last week of the previous year; and if December 29th, 30th, or 31st falls on Monday, that day and later belong to week 1 of the next year. For consistency with %Y, it always has at least four characters. Example: "%G" for Saturday 2nd January 1999 gives "1998", and for Tuesday 30th December 1997 gives "1998". [tm_year, tm_wday, tm_yday]
%hSynonym for "%b". [tm_mon]
%HThe hour (on a 24-hour clock), formatted with two digits (from
‘00’ to ‘23’). [tm_hour]
%IThe hour (on a 12-hour clock), formatted with two digits (from
‘01’ to ‘12’). [tm_hour]
%jThe count of days in the year, formatted with three digits
(from ‘001’ to ‘366’). [tm_yday]
%kThe hour (on a 24-hour clock), formatted with leading space if single
digit (from ‘0’ to ‘23’). Non-POSIX extension (c.p. %I). [tm_hour]
%lThe hour (on a 12-hour clock), formatted with leading space if single
digit (from ‘1’ to ‘12’). Non-POSIX extension (c.p. %H). [tm_hour]
%mThe month number, formatted with two digits (from ‘01’ to ‘12’).
[tm_mon]
%MThe minute, formatted with two digits (from ‘00’ to ‘59’). [tm_min]
%nA newline character (‘\n’).
%OxIn some locales, the O modifier selects alternative digit characters
for certain modifiers x. In newlib, it is ignored, and treated as %x.
%pEither ‘AM’ or ‘PM’ as appropriate, or the corresponding strings for
the current locale. [tm_hour]
%PSame as ’%p’, but in lowercase. This is a GNU extension. [tm_hour]
%rReplaced by the time in a.m. and p.m. notation. In the "C" locale this is equivalent to "%I:%M:%S %p". In locales which don’t define a.m./p.m. notations, the result is an empty string. [tm_sec, tm_min, tm_hour]
%RThe 24-hour time, to the minute. Equivalent to "%H:%M". [tm_min, tm_hour]
%sThe time elapsed, in seconds, since the start of the Unix epoch at 1970-01-01 00:00:00 UTC.
%SThe second, formatted with two digits (from ‘00’ to ‘60’). The
value 60 accounts for the occasional leap second. [tm_sec]
%tA tab character (‘\t’).
%TThe 24-hour time, to the second. Equivalent to "%H:%M:%S". [tm_sec, tm_min, tm_hour]
%uThe weekday as a number, 1-based from Monday (from ‘1’ to
‘7’). [tm_wday]
%UThe week number, where weeks start on Sunday, week 1 contains the first
Sunday in a year, and earlier days are in week 0. Formatted with two
digits (from ‘00’ to ‘53’). See also %W. [tm_wday, tm_yday]
%VThe week number, where weeks start on Monday, week 1 contains January 4th,
and earlier days are in the previous year. Formatted with two digits
(from ‘01’ to ‘53’). See also %G. [tm_year, tm_wday, tm_yday]
%wThe weekday as a number, 0-based from Sunday (from ‘0’ to ‘6’).
[tm_wday]
%WThe week number, where weeks start on Monday, week 1 contains the first
Monday in a year, and earlier days are in week 0. Formatted with two
digits (from ‘00’ to ‘53’). [tm_wday, tm_yday]
%xReplaced by the preferred date representation in the current locale. In the "C" locale this is equivalent to "%m/%d/%y". [tm_mon, tm_mday, tm_year]
%XReplaced by the preferred time representation in the current locale. In the "C" locale this is equivalent to "%H:%M:%S". [tm_sec, tm_min, tm_hour]
%yThe last two digits of the year (from ‘00’ to ‘99’). [tm_year]
(Implementation interpretation: always positive, even for negative years.)
%YThe full year, equivalent to %C%y. It will always have at least four
characters, but may have more. The year is accurate even when tm_year
added to the offset of 1900 overflows an int. [tm_year]
%zThe offset from UTC. The format consists of a sign (negative is west of Greewich), two characters for hour, then two characters for minutes (-hhmm or +hhmm). If tm_isdst is negative, the offset is unknown and no output is generated; if it is zero, the offset is the standard offset for the current time zone; and if it is positive, the offset is the daylight savings offset for the current timezone. The offset is determined from the TZ environment variable, as if by calling tzset(). [tm_isdst]
%ZThe time zone name. If tm_isdst is negative, no output is generated. Otherwise, the time zone name is based on the TZ environment variable, as if by calling tzset(). [tm_isdst]
%%A single character, ‘%’.
Returns
When the formatted time takes up no more than maxsize characters,
the result is the length of the formatted string. Otherwise, if the
formatting operation was abandoned due to lack of room, the result is
0, and the string starting at s corresponds to just those
parts of *format that could be completely filled in within the
maxsize limit.
Portability
ANSI C requires strftime, but does not specify the contents of
*s when the formatted string would require more than
maxsize characters. Unrecognized specifiers and fields of
timp that are out of range cause undefined results. Since some
formats expand to 0 bytes, it is wise to set *s to a nonzero
value beforehand to distinguish between failure and an empty string.
This implementation does not support s being NULL, nor overlapping
s and format.
strftime_l is POSIX-1.2008.
strftime and strftime_l require no supporting OS subroutines.
Bugs
(NOT Cygwin:) strftime ignores the LC_TIME category of the current
locale, hard-coding the "C" locale settings.
Next: __tz_lock, __tz_unlock—lock time zone global variables, Previous: strftime, strftime_l—convert date and time to a formatted string, Up: Time Functions (time.h) [Contents][Index]
time—get current calendar time (as single number)Synopsis
#include <time.h> time_t time(time_t *t);
Description
time looks up the best available representation of the current
time and returns it, encoded as a time_t. It stores the same
value at t unless the argument is NULL.
Returns
A -1 result means the current time is not available; otherwise the
result represents the current time.
Portability
ANSI C requires time.
Supporting OS subroutine required: Some implementations require
gettimeofday.
Next: tzset—set timezone characteristics from TZ environment variable, Previous: time—get current calendar time (as single number), Up: Time Functions (time.h) [Contents][Index]
__tz_lock, __tz_unlock—lock time zone global variablesSynopsis
#include "local.h" void __tz_lock (void); void __tz_unlock (void);
Description
The tzset facility functions call these functions when they need to
ensure the values of global variables. The version of these routines
supplied in the library use the lock API defined in sys/lock.h. If multiple
threads of execution can call the time functions and give up scheduling in
the middle, then you you need to define your own versions of these functions
in order to safely lock the time zone variables during a call. If you do
not, the results of localtime, mktime, ctime, and strftime
are undefined.
The lock __tz_lock may not be called recursively; that is,
a call __tz_lock will always lock all subsequent __tz_lock calls
until the corresponding __tz_unlock call on the same thread is made.
Previous: __tz_lock, __tz_unlock—lock time zone global variables, Up: Time Functions (time.h) [Contents][Index]
tzset—set timezone characteristics from TZ environment variableSynopsis
#include <time.h> void tzset(void); void _tzset_r (struct _reent *reent_ptr);
Description
tzset examines the TZ environment variable and sets up the three
external variables: _timezone, _daylight, and tzname. The
value of _timezone shall be the offset from the current time zone
to GMT. The value of _daylight shall be 0 if there is no daylight
savings time for the current time zone, otherwise it will be non-zero.
The tzname array has two entries: the first is the name of the
standard time zone, the second is the name of the daylight-savings time
zone.
The TZ environment variable is expected to be in the following POSIX format:
stdoffset1[dst[offset2][,start[/time1],end[/time2]]]
where: std is the name of the standard time-zone (minimum 3 chars) offset1 is the value to add to local time to arrive at Universal time it has the form: hh[:mm[:ss]] dst is the name of the alternate (daylight-savings) time-zone (min 3 chars) offset2 is the value to add to local time to arrive at Universal time it has the same format as the std offset start is the day that the alternate time-zone starts time1 is the optional time that the alternate time-zone starts (this is in local time and defaults to 02:00:00 if not specified) end is the day that the alternate time-zone ends time2 is the time that the alternate time-zone ends (it is in local time and defaults to 02:00:00 if not specified)
Note that there is no white-space padding between fields. Also note that if TZ is null, the default is Universal GMT which has no daylight-savings time. If TZ is empty, the default EST5EDT is used.
The function _tzset_r is identical to tzset only it is reentrant
and is used for applications that use multiple threads.
Returns
There is no return value.
Portability
tzset is part of the POSIX standard.
Supporting OS subroutine required: None
Next: Reentrancy, Previous: Time Functions (time.h), Up: The Red Hat newlib C Library [Contents][Index]
A locale is the name for a collection of parameters (affecting
collating sequences and formatting conventions) that may be different
depending on location or culture. The "C" locale is the only
one defined in the ANSI C standard.
This is a minimal implementation, supporting only the required "C"
value for locale; strings representing other locales are not
honored. ("" is also accepted; it represents the default locale
for an implementation, here equivalent to "C").
locale.h defines the structure lconv to collect the
information on a locale, with the following fields:
char *decimal_pointThe decimal point character used to format “ordinary” numbers (all
numbers except those referring to amounts of money). "." in the
C locale.
char *thousands_sepThe character (if any) used to separate groups of digits, when
formatting ordinary numbers.
"" in the C locale.
char *groupingSpecifications for how many digits to group (if any grouping is done at
all) when formatting ordinary numbers. The numeric value of each
character in the string represents the number of digits for the next
group, and a value of 0 (that is, the string’s trailing
NULL) means to continue grouping digits using the last value
specified. Use CHAR_MAX to indicate that no further grouping is
desired. "" in the C locale.
char *int_curr_symbolThe international currency symbol (first three characters), if any, and
the character used to separate it from numbers.
"" in the C locale.
char *currency_symbolThe local currency symbol, if any.
"" in the C locale.
char *mon_decimal_pointThe symbol used to delimit fractions in amounts of money.
"" in the C locale.
char *mon_thousands_sepSimilar to thousands_sep, but used for amounts of money.
"" in the C locale.
char *mon_groupingSimilar to grouping, but used for amounts of money.
"" in the C locale.
char *positive_signA string to flag positive amounts of money when formatting.
"" in the C locale.
char *negative_signA string to flag negative amounts of money when formatting.
"" in the C locale.
char int_frac_digitsThe number of digits to display when formatting amounts of money to
international conventions.
CHAR_MAX (the largest number representable as a char) in
the C locale.
char frac_digitsThe number of digits to display when formatting amounts of money to
local conventions.
CHAR_MAX in the C locale.
char p_cs_precedes1 indicates the local currency symbol is used before a
positive or zero formatted amount of money; 0 indicates
the currency symbol is placed after the formatted number.
CHAR_MAX in the C locale.
char p_sep_by_space1 indicates the local currency symbol must be separated from
positive or zero numbers by a space; 0 indicates that it
is immediately adjacent to numbers.
CHAR_MAX in the C locale.
char n_cs_precedes1 indicates the local currency symbol is used before a
negative formatted amount of money; 0 indicates
the currency symbol is placed after the formatted number.
CHAR_MAX in the C locale.
char n_sep_by_space1 indicates the local currency symbol must be separated from
negative numbers by a space; 0 indicates that it
is immediately adjacent to numbers.
CHAR_MAX in the C locale.
char p_sign_posnControls the position of the positive sign for
numbers representing money. 0 means parentheses surround the
number; 1 means the sign is placed before both the number and the
currency symbol; 2 means the sign is placed after both the number
and the currency symbol; 3 means the sign is placed just before
the currency symbol; and 4 means the sign is placed just after
the currency symbol.
CHAR_MAX in the C locale.
char n_sign_posnControls the position of the negative sign for numbers
representing money, using the same rules as p_sign_posn.
CHAR_MAX in the C locale.
Up: Locale (locale.h) [Contents][Index]
setlocale, localeconv—select or query localeSynopsis
#include <locale.h>
char *setlocale(int category, const char *locale);
lconv *localeconv(void);
char *_setlocale_r(void *reent,
int category, const char *locale);
lconv *_localeconv_r(void *reent);
Description
setlocale is the facility defined by ANSI C to condition the
execution environment for international collating and formatting
information; localeconv reports on the settings of the current
locale.
This is a minimal implementation, supporting only the required "POSIX"
and "C" values for locale; strings representing other locales are not
honored unless _MB_CAPABLE is defined.
If _MB_CAPABLE is defined, POSIX locale strings are allowed, following the form
language[_TERRITORY][.charset][@modifier]
"language" is a two character string per ISO 639, or, if not available
for a given language, a three character string per ISO 639-3.
"TERRITORY" is a country code per ISO 3166. For "charset" and
"modifier" see below.
Additionally to the POSIX specifier, the following extension is supported
for backward compatibility with older implementations using newlib:
"C-charset".
Instead of "C-", you can also specify "C.". Both variations allow
to specify language neutral locales while using other charsets than ASCII,
for instance "C.UTF-8", which keeps all settings as in the C locale,
but uses the UTF-8 charset.
The following charsets are recognized:
"UTF-8", "JIS", "EUCJP", "SJIS", "KOI8-R", "KOI8-U",
"GEORGIAN-PS", "PT154", "TIS-620", "ISO-8859-x" with
1 <= x <= 16, or "CPxxx" with xxx in [437, 720, 737, 775, 850, 852, 855,
857, 858, 862, 866, 874, 932, 1125, 1250, 1251, 1252, 1253, 1254, 1255, 1256,
1257, 1258].
Charsets are case insensitive. For instance, "EUCJP" and "eucJP"
are equivalent. Charset names with dashes can also be written without
dashes, as in "UTF8", "iso88591" or "koi8r". "EUCJP" and
"EUCKR" are also recognized with dash, "EUC-JP" and "EUC-KR".
Full support for all of the above charsets requires that newlib has been
build with multibyte support and support for all ISO and Windows Codepage.
Otherwise all singlebyte charsets are simply mapped to ASCII. Right now,
only newlib for Cygwin is built with full charset support by default.
Under Cygwin, this implementation additionally supports the charsets
"GBK", "GB2312", "eucCN", "eucKR", and "Big5". Cygwin
does not support "JIS".
Cygwin additionally supports locales from the file /usr/share/locale/locale.alias.
("" is also accepted; if given, the settings are read from the
corresponding LC_* environment variables and $LANG according to POSIX rules.)
This implementation also supports the modifiers "cjknarrow" and
"cjkwide", which affect how the functions wcwidth and wcswidth
handle characters from the "CJK Ambiguous Width" category of characters
described at http://www.unicode.org/reports/tr11/#Ambiguous.
These characters have a width of 1 for singlebyte charsets and UTF-8,
and a width of 2 for multibyte charsets other than UTF-8. Specifying
"cjknarrow" or "cjkwide" forces a width of 1 or 2, respectively.
This implementation also supports the modifier "cjksingle"
to enforce single-width character properties.
If you use NULL as the locale argument, setlocale returns a
pointer to the string representing the current locale. The acceptable
values for category are defined in ‘locale.h’ as macros
beginning with "LC_".
localeconv returns a pointer to a structure (also defined in
‘locale.h’) describing the locale-specific conventions currently
in effect.
_localeconv_r and _setlocale_r are reentrant versions of
localeconv and setlocale respectively. The extra argument
reent is a pointer to a reentrancy structure.
Returns
A successful call to setlocale returns a pointer to a string
associated with the specified category for the new locale. The string
returned by setlocale is such that a subsequent call using that
string will restore that category (or all categories in case of LC_ALL),
to that state. The application shall not modify the string returned
which may be overwritten by a subsequent call to setlocale.
On error, setlocale returns NULL.
localeconv returns a pointer to a structure of type lconv,
which describes the formatting and collating conventions in effect (in
this implementation, always those of the C locale).
Portability
ANSI C requires setlocale, but the only locale required across all
implementations is the C locale.
Notes
There is no ISO-8859-12 codepage. It’s also refused by this implementation.
No supporting OS subroutines are required.
Next: Miscellaneous Macros and Functions, Previous: Locale (locale.h), Up: The Red Hat newlib C Library [Contents][Index]
Reentrancy is a characteristic of library functions which allows multiple processes to use the same address space with assurance that the values stored in those spaces will remain constant between calls. The Red Hat newlib implementation of the library functions ensures that whenever possible, these library functions are reentrant. However, there are some functions that can not be trivially made reentrant. Hooks have been provided to allow you to use these functions in a fully reentrant fashion.
These hooks use the structure _reent defined in reent.h.
A variable defined as ‘struct _reent’ is called a reentrancy
structure. All functions which must manipulate global information are
available in two versions. The first version has the usual name, and
uses a single global instance of the reentrancy structure. The second
has a different name, normally formed by prepending ‘_’ and
appending ‘_r’, and takes a pointer to the particular reentrancy
structure to use.
For example, the function fopen takes two arguments, file
and mode, and uses the global reentrancy structure. The function
_fopen_r takes the arguments, struct_reent, which is a
pointer to an instance of the reentrancy structure, file
and mode.
There are two versions of ‘struct _reent’, a normal one and one
for small memory systems, controlled by the _REENT_SMALL
definition from the (automatically included) <sys/config.h>.
Each function which uses the global reentrancy structure uses the global
variable _impure_ptr, which points to a reentrancy structure.
This means that you have two ways to achieve reentrancy. Both require that each thread of execution control initialize a unique global variable of type ‘struct _reent’:
_impure_ptr,
and call the standard library subroutines.
The following functions are provided in both reentrant and non-reentrant versions.
Equivalent for errno variable:
_errno_r
Locale functions:
_localeconv_r _setlocale_r
Equivalents for stdio variables:
_stdin_r _stdout_r _stderr_r
Stdio functions:
_fdopen_r _perror_r _tempnam_r _fopen_r _putchar_r _tmpnam_r _getchar_r _puts_r _tmpfile_r _gets_r _remove_r _vfprintf_r _iprintf_r _rename_r _vsnprintf_r _mkstemp_r _snprintf_r _vsprintf_r _mktemp_t _sprintf_r
Signal functions:
_init_signal_r _signal_r _kill_r __sigtramp_r _raise_r
Stdlib functions:
_calloc_r _mblen_r _setenv_r _dtoa_r _mbstowcs_r _srand_r _free_r _mbtowc_r _strtod_r _getenv_r _memalign_r _strtol_r _mallinfo_r _mstats_r _strtoul_r _malloc_r _putenv_r _system_r _malloc_r _rand_r _wcstombs_r _malloc_stats_r _realloc_r _wctomb_r
String functions:
_strdup_r _strtok_r
System functions:
_close_r _link_r _unlink_r _execve_r _lseek_r _wait_r _fcntl_r _open_r _write_r _fork_r _read_r _fstat_r _sbrk_r _gettimeofday_r _stat_r _getpid_r _times_r
Time function:
_asctime_r
Next: Posix Functions, Previous: Reentrancy, Up: The Red Hat newlib C Library [Contents][Index]
This chapter describes miscellaneous routines not covered elsewhere.
ffs—find first bit set in a word__retarget_lock_init, __retarget_lock_init_recursive, __retarget_lock_close, __retarget_lock_close_recursive, __retarget_lock_acquire, __retarget_lock_acquire_recursive, __retarget_lock_try_acquire, __retarget_lock_try_acquire_recursive, __retarget_lock_release, __retarget_lock_release_recursive—locking routinesunctrl—get printable representation of a character
Next: __retarget_lock_init, __retarget_lock_init_recursive, __retarget_lock_close, __retarget_lock_close_recursive, __retarget_lock_acquire, __retarget_lock_acquire_recursive, __retarget_lock_try_acquire, __retarget_lock_try_acquire_recursive, __retarget_lock_release, __retarget_lock_release_recursive—locking routines, Up: Miscellaneous Macros and Functions [Contents][Index]
ffs—find first bit set in a wordSynopsis
#include <strings.h> int ffs(int word);
Description
ffs returns the first bit set in a word.
Returns
ffs returns 0 if c is 0, 1 if c is odd, 2 if c is a multiple of
2, etc.
Portability
ffs is not ANSI C.
No supporting OS subroutines are required.
Next: unctrl—get printable representation of a character, Previous: ffs—find first bit set in a word, Up: Miscellaneous Macros and Functions [Contents][Index]
__retarget_lock_init, __retarget_lock_init_recursive, __retarget_lock_close, __retarget_lock_close_recursive, __retarget_lock_acquire, __retarget_lock_acquire_recursive, __retarget_lock_try_acquire, __retarget_lock_try_acquire_recursive, __retarget_lock_release, __retarget_lock_release_recursive—locking routinesSynopsis
#include <lock.h> struct __lock __lock___sinit_recursive_mutex; struct __lock __lock___sfp_recursive_mutex; struct __lock __lock___atexit_recursive_mutex; struct __lock __lock___at_quick_exit_mutex; struct __lock __lock___malloc_recursive_mutex; struct __lock __lock___env_recursive_mutex; struct __lock __lock___tz_mutex; struct __lock __lock___dd_hash_mutex; struct __lock __lock___arc4random_mutex; void __retarget_lock_init (_LOCK_T * lock_ptr); void __retarget_lock_init_recursive (_LOCK_T * lock_ptr); void __retarget_lock_close (_LOCK_T lock); void __retarget_lock_close_recursive (_LOCK_T lock); void __retarget_lock_acquire (_LOCK_T lock); void __retarget_lock_acquire_recursive (_LOCK_T lock); int __retarget_lock_try_acquire (_LOCK_T lock); int __retarget_lock_try_acquire_recursive (_LOCK_T lock); void __retarget_lock_release (_LOCK_T lock); void __retarget_lock_release_recursive (_LOCK_T lock);
Description
Newlib was configured to allow the target platform to provide the locking
routines and static locks at link time. As such, a dummy default
implementation of these routines and static locks is provided for
single-threaded application to link successfully out of the box on bare-metal
systems.
For multi-threaded applications the target platform is required to provide an implementation for all these routines and static locks. If some routines or static locks are missing, the link will fail with doubly defined symbols.
Portability
These locking routines and static lock are newlib-specific. Supporting OS
subroutines are required for linking multi-threaded applications.
Previous: __retarget_lock_init, __retarget_lock_init_recursive, __retarget_lock_close, __retarget_lock_close_recursive, __retarget_lock_acquire, __retarget_lock_acquire_recursive, __retarget_lock_try_acquire, __retarget_lock_try_acquire_recursive, __retarget_lock_release, __retarget_lock_release_recursive—locking routines, Up: Miscellaneous Macros and Functions [Contents][Index]
unctrl—get printable representation of a characterSynopsis
#include <unctrl.h> char *unctrl(int c); int unctrllen(int c);
Description
unctrl is a macro which returns the printable representation of c
as a string.
unctrllen is a macro which returns the length of the printable
representation of c.
Returns
unctrl returns a string of the printable representation of c.
unctrllen returns the length of the string which is the printable
representation of c.
Portability
unctrl and unctrllen are not ANSI C.
No supporting OS subroutines are required.
Next: Encoding conversions (iconv.h), Previous: Miscellaneous Macros and Functions, Up: The Red Hat newlib C Library [Contents][Index]
This chapter groups several utility functions specified by POSIX, but not by C. Each function documents which header to use.
popen, pclose—tie a stream to a command stringSynopsis
#include <stdio.h> FILE *popen(const char *s, const char *mode); int pclose(FILE *f);
Description
Use popen to create a stream to a child process executing a
command string *s as processed by /bin/sh on your system.
The argument mode must start with either ‘r’, where the stream
reads from the child’s stdout, or ‘w’, where the stream writes
to the child’s stdin. As an extension, mode may also contain
‘e’ to set the close-on-exec bit of the parent’s file descriptor.
The stream created by popen must be closed by pclose to avoid
resource leaks.
Streams created by prior calls to popen are not visible in
subsequent popen children, regardless of the close-on-exec bit.
Use “system(NULL)” to test whether your system has /bin/sh
available.
Returns
popen returns a file stream opened with the specified mode,
or NULL if a child process could not be created. pclose
returns -1 if the stream was not created by popen or if the
application used wait or similar to steal the status; otherwise
it returns the exit status of the child which can be interpreted
in the same manner as a status obtained by waitpid.
Portability
POSIX.2 requires popen and pclose, but only specifies a mode
of just r or w. Where sh is found is left unspecified.
Supporting OS subroutines required: _exit, _execve, _fork_r,
_wait_r, pipe, fcntl, sbrk.
Previous: popen, pclose—tie a stream to a command string, Up: Posix Functions [Contents][Index]
posix_spawn, posix_spawnp—spawn a processSynopsis
#include <spawn.h>
int posix_spawn(pid_t *pid, const char *path,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp,
char *const argv[], char *const envp[]);
int posix_spawnp(pid_t *pid, const char *file,
const posix_spawn_file_actions_t *file_actions,
const posix_spawnattr_t *attrp,
char *const argv[], char *const envp[]);
Description
Use posix_spawn and posix_spawnp to create a new child process
from the specified process image file. argc is the argument count
and argv is an array of argument strings passed to the new program.
envp is an array of stings, which are passed as environment to the
new program.
The path argument to posix_spawn identifies the new process
image file to execute. The file argument to posix_spawnp is
used to construct a pathname that identifies the new process image
file by duplicating the actions of the shell in searching for an
executable file if the specified filename does not contain a ‘/’
character. The file is sought in the colon-separated list of
directory pathnames specified in the PATH environment variable.
The file descriptors remain open across posix_spawn and
posix_spawnp except for those marked as close-on-exec. The open
file descriptors in the child process can be modified by the spawn file
actions object pointed to by file_actions.
The spawn attributes object type pointed to by attrp argument
may contain any of the attributes defined in spawn.h.
Returns
posix_spawn and posix_spawnp return the process ID of the newly
spawned child process in the variable pointed by a non-NULL *pid
argument and zero as the function return value upon successful
completion. Otherwise, posix_spawn and posix_spawnp return an
error number as the function return value to indicate the error; the
value stored into the variable pointed to by a non-NULL *pid
argument is unspecified.
Portability
POSIX.1-2008 requires posix_spawn and posix_spawnp.
Supporting OS subroutines required: _close, dup2, _fcntl,
_execve, execvpe, _exit, _open, sigaction,
sigprocmask, waitpid, sched_setscheduler,
sched_setparam, setegid, seteuid, setpgid, vfork.
Next: Overflow Protection, Previous: Posix Functions, Up: The Red Hat newlib C Library [Contents][Index]
This chapter describes the Newlib iconv library. The iconv functions declarations are in iconv.h.
iconv, iconv_open, iconv_close—charset conversion routinesNext: Introduction to iconv, Up: Encoding conversions (iconv.h) [Contents][Index]
iconv, iconv_open, iconv_close—charset conversion routinesSynopsis
#include <iconv.h>
iconv_t iconv_open (const char *to, const char *from);
int iconv_close (iconv_t cd);
size_t iconv (iconv_t cd, char **restrict inbuf,
size_t *restrict inbytesleft,
char **restrict outbuf,
size_t *restrict outbytesleft);
iconv_t _iconv_open_r (struct _reent *rptr,
const char *to, const char *from);
int _iconv_close_r (struct _reent *rptr, iconv_t cd);
size_t _iconv_r (struct _reent *rptr,
iconv_t cd, const char **inbuf,
size_t *inbytesleft,
char **outbuf, size_t *outbytesleft);
Description
The function iconv converts characters from in which are in one
encoding to characters of another encoding, outputting them to out.
The value inleft specifies the number of input bytes to convert whereas
the value outleft specifies the size remaining in the out buffer.
The conversion descriptor cd specifies the conversion being performed
and is created via iconv_open.
An iconv conversion stops if: the input bytes are exhausted, the output
buffer is full, an invalid input character sequence occurs, or the
conversion specifier is invalid.
The function iconv_open is used to specify a conversion from one
encoding: from to another: to. The result of the call is
to create a conversion specifier that can be used with iconv.
The function iconv_close is used to close a conversion specifier after
it is no longer needed.
The _iconv_r, _iconv_open_r, and _iconv_close_r functions are
reentrant versions of iconv, iconv_open, and iconv_close,
respectively. An additional reentrancy struct pointer: rptr is passed
to properly set errno.
Returns
The iconv function returns the number of non-identical conversions
performed. If an error occurs, (size_t)-1 is returned and errno
is set appropriately. The values of inleft, in, out,
and outleft are modified to indicate how much input was processed
and how much output was created.
The iconv_open function returns either a valid conversion specifier
or (iconv_t)-1 to indicate failure. If failure occurs, errno is set
appropriately.
The iconv_close function returns 0 on success or -1 on failure.
If failure occurs errno is set appropriately.
Portability
iconv, iconv_open, and iconv_close are non-ANSI and are specified
by the Single Unix specification.
No supporting OS subroutine calls are required.
Next: Supported encodings, Previous: iconv, iconv_open, iconv_close—charset conversion routines, Up: Encoding conversions (iconv.h) [Contents][Index]
The iconv library is intended to convert characters from one encoding to another. It implements iconv(), iconv_open() and iconv_close() calls, which are defined by the Single Unix Specification.
In addition to these user-level interfaces, the iconv library also has several useful interfaces which are needed to support coding capabilities of the Newlib Locale infrastructure. Since Locale support also needs to convert various character sets to and from the wide characters set, the iconv library shares it’s capabilities with the Newlib Locale subsystem. Moreover, the iconv library supports several features which are only needed for the Locale infrastructure (for example, the MB_CUR_MAX value).
The Newlib iconv library was created using concepts from another iconv library implemented by Konstantin Chuguev (ver 2.0). The Newlib iconv library was rewritten from scratch and contains a lot of improvements with respect to the original iconv library.
Terms like encoding or character set aren’t well defined and are often used with various meanings. The following are the definitions of terms which are used in this documentation as well as in the iconv library implementation:
Users usually deal with encodings, for example, KOI8-R, Unicode, UTF-8, ASCII, etc. Encodings are formed by the following chain of steps:
Thus, an encoding may be considered as one or more CCS + CES.
Sometimes, there is no CES and in such cases encoding is equivalent to CCS, e.g. KOI8-R or ASCII.
An example of a more complicated encoding is UTF-8 which is the UCS (or Unicode) CCS plus the UTF-8 CES.
The following is a brief list of iconv library features:
Next: iconv design decisions, Previous: Introduction to iconv, Up: Encoding conversions (iconv.h) [Contents][Index]
The following is the list of currently supported encodings. The first column corresponds to the encoding name, the second column is the list of aliases, the third column is its CES and CCS components names, and the fourth column is a short description.
| Name | Aliases | CES/CCS | Short description |
| big5 | csbig5, big_five, bigfive, cn_big5, cp950 | table_pcs / big5, us_ascii | The encoding for the Traditional Chinese. |
| cp775 | ibm775, cspc775baltic | table / cp775 | The updated version of CP 437 that supports the balitic languages. |
| cp850 | ibm850, 850, cspc850multilingual | table / cp850 | IBM 850 - the updated version of CP 437 where several Latin 1 characters have been added instead of some less-often used characters like the line-drawing and the greek ones. |
| cp852 | ibm852, 852, cspcp852 | IBM 852 - the updated version of CP 437 where several Latin 2 characters have been added instead of some less-often used characters like the line-drawing and the greek ones. | |
| cp855 | ibm855, 855, csibm855 | table / cp855 | IBM 855 - the updated version of CP 437 that supports Cyrillic. |
| cp866 | 866, IBM866, CSIBM866 | table / cp866 | IBM 866 - the updated version of CP 855 which follows more the logical Russian alphabet ordering of the alternative variant that is preferred by many Russian users. |
| euc_jp | eucjp | euc / jis_x0208_1990, jis_x0201_1976, jis_x0212_1990 | EUC-JP - The EUC for Japanese. |
| euc_kr | euckr | euc / ksx1001 | EUC-KR - The EUC for Korean. |
| euc_tw | euctw | euc / cns11643_plane1, cns11643_plane2, cns11643_plane14 | EUC-TW - The EUC for Traditional Chinese. |
| iso_8859_1 | iso8859_1, iso88591, iso_8859_1:1987, iso_ir_100, latin1, l1, ibm819, cp819, csisolatin1 | table / iso_8859_1 | ISO 8859-1:1987 - Latin 1, West European. |
| iso_8859_10 | iso_8859_10:1992, iso_ir_157, iso885910, latin6, l6, csisolatin6, iso8859_10 | table / iso_8859_10 | ISO 8859-10:1992 - Latin 6, Nordic. |
| iso_8859_11 | iso8859_11, iso885911 | table / iso_8859_11 | ISO 8859-11 - Thai. |
| iso_8859_13 | iso_8859_13:1998, iso8859_13, iso885913 | table / iso_8859_13 | ISO 8859-13:1998 - Latin 7, Baltic Rim. |
| iso_8859_14 | iso_8859_14:1998, iso885914, iso8859_14 | table / iso_8859_14 | ISO 8859-14:1998 - Latin 8, Celtic. |
| iso_8859_15 | iso885915, iso_8859_15:1998, iso8859_15, | table / iso_8859_15 | ISO 8859-15:1998 - Latin 9, West Europe, successor of Latin 1. |
| iso_8859_2 | iso8859_2, iso88592, iso_8859_2:1987, iso_ir_101, latin2, l2, csisolatin2 | table / iso_8859_2 | ISO 8859-2:1987 - Latin 2, East European. |
| iso_8859_3 | iso_8859_3:1988, iso_ir_109, iso8859_3, latin3, l3, csisolatin3, iso88593 | table / iso_8859_3 | ISO 8859-3:1988 - Latin 3, South European. |
| iso_8859_4 | iso8859_4, iso88594, iso_8859_4:1988, iso_ir_110, latin4, l4, csisolatin4 | table / iso_8859_4 | ISO 8859-4:1988 - Latin 4, North European. |
| iso_8859_5 | iso8859_5, iso88595, iso_8859_5:1988, iso_ir_144, cyrillic, csisolatincyrillic | table / iso_8859_5 | ISO 8859-5:1988 - Cyrillic. |
| iso_8859_6 | iso_8859_6:1987, iso_ir_127, iso8859_6, ecma_114, asmo_708, arabic, csisolatinarabic, iso88596 | table / iso_8859_6 | ISO i8859-6:1987 - Arabic. |
| iso_8859_7 | iso_8859_7:1987, iso_ir_126, iso8859_7, elot_928, ecma_118, greek, greek8, csisolatingreek, iso88597 | table / iso_8859_7 | ISO 8859-7:1987 - Greek. |
| iso_8859_8 | iso_8859_8:1988, iso_ir_138, iso8859_8, hebrew, csisolatinhebrew, iso88598 | table / iso_8859_8 | ISO 8859-8:1988 - Hebrew. |
| iso_8859_9 | iso_8859_9:1989, iso_ir_148, iso8859_9, latin5, l5, csisolatin5, iso88599 | table / iso_8859_9 | ISO 8859-9:1989 - Latin 5, Turkish. |
| iso_ir_111 | ecma_cyrillic, koi8_e, koi8e, csiso111ecmacyrillic | table / iso_ir_111 | ISO IR 111/ECMA Cyrillic. |
| koi8_r | cskoi8r, koi8r, koi8 | table / koi8_r | RFC 1489 Cyrillic. |
| koi8_ru | koi8ru | table / koi8_ru | The obsolete Ukrainian. |
| koi8_u | koi8u | table / koi8_u | RFC 2319 Ukrainian. |
| koi8_uni | koi8uni | table / koi8_uni | KOI8 Unified. |
| ucs_2 | ucs2, iso_10646_ucs_2, iso10646_ucs_2, iso_10646_ucs2, iso10646_ucs2, iso10646ucs2, csUnicode | ucs_2 / (UCS) | ISO-10646-UCS-2. Big Endian, NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_2_internal | ucs2_internal, ucs_2internal, ucs2internal | ucs_2_internal / (UCS) | ISO-10646-UCS-2 in system byte order. NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_2be | ucs2be | ucs_2 / (UCS) | Big Endian version of ISO-10646-UCS-2 (in fact, equivalent to ucs_2). Big Endian, NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_2le | ucs2le | ucs_2 / (UCS) | Little Endian version of ISO-10646-UCS-2. Little Endian, NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_4 | ucs4, iso_10646_ucs_4, iso10646_ucs_4, iso_10646_ucs4, iso10646_ucs4, iso10646ucs4 | ucs_4 / (UCS) | ISO-10646-UCS-4. Big Endian, NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_4_internal | ucs4_internal, ucs_4internal, ucs4internal | ucs_4_internal / (UCS) | ISO-10646-UCS-4 in system byte order. NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_4be | ucs4be | ucs_4 / (UCS) | Big Endian version of ISO-10646-UCS-4 (in fact, equivalent to ucs_4). Big Endian, NBSP is always interpreted as NBSP (BOM isn’t supported). |
| ucs_4le | ucs4le | ucs_4 / (UCS) | Little Endian version of ISO-10646-UCS-4. Little Endian, NBSP is always interpreted as NBSP (BOM isn’t supported). |
| us_ascii | ansi_x3.4_1968, ansi_x3.4_1986, iso_646.irv:1991, ascii, iso646_us, us, ibm367, cp367, csascii | us_ascii / (ASCII) | 7-bit ASCII. |
| utf_16 | utf16 | utf_16 / (UCS) | RFC 2781 UTF-16. The very first NBSP code in stream is interpreted as BOM. |
| utf_16be | utf16be | utf_16 / (UCS) | Big Endian version of RFC 2781 UTF-16. NBSP is always interpreted as NBSP (BOM isn’t supported). |
| utf_16le | utf16le | utf_16 / (UCS) | Little Endian version of RFC 2781 UTF-16. NBSP is always interpreted as NBSP (BOM isn’t supported). |
| utf_8 | utf8 | utf_8 / (UCS) | RFC 3629 UTF-8. |
| win_1250 | cp1250 | Win-1250 Croatian. | |
| win_1251 | cp1251 | table / win_1251 | Win-1251 - Cyrillic. |
| win_1252 | cp1252 | table / win_1252 | Win-1252 - Latin 1. |
| win_1253 | cp1253 | table / win_1253 | Win-1253 - Greek. |
| win_1254 | cp1254 | table / win_1254 | Win-1254 - Turkish. |
| win_1255 | cp1255 | table / win_1255 | Win-1255 - Hebrew. |
| win_1256 | cp1256 | table / win_1256 | Win-1256 - Arabic. |
| win_1257 | cp1257 | table / win_1257 | Win-1257 - Baltic. |
| win_1258 | cp1258 | table / win_1258 | Win-1258 - Vietnamese7 that supports Cyrillic. |
Next: iconv configuration, Previous: Supported encodings, Up: Encoding conversions (iconv.h) [Contents][Index]
The first iconv library design issue arises when considering the following two design approaches:
It’s obvious, that we have tradeoff between commonality/flexibility and efficiency: the first method is more efficient since it converts directly; however, it isn’t so flexible since for each encoding pair a distinct module is needed.
The Newlib iconv model uses the second method and always converts through the 32-bit UCS but its design also allows one to write specialized conversion modules if the conversion speed is critical.
The second design issue is how to break down (decompose) encodings. The Newlib iconv library uses the fact that any encoding may be considered as one or more CCS plus a CES. It also decomposes its conversion modules on CES converter plus one or more CCS tables. CCS tables map CCS to UCS and vice versa; the CES converters map CCS to the encoding and vice versa.
As the example, let’s consider the conversion from the big5 encoding to the EUC-TW encoding. The big5 encoding may be decomposed to the ASCII and BIG5 CCS-es plus the BIG5 CES. EUC-TW may be decomposed on the CNS11643_PLANE1, CNS11643_PLANE2, and CNS11643_PLANE14 CCS-es plus the EUC CES.
The euc_jp -> big5 conversion is performed as follows:
Analogously, the backward conversion is performed as follows:
Note, the above is just an example and real names (which are implemented in the Newlib iconv) of the CES converters and the CCS tables are slightly different.
The third design issue also relates to flexibility. Obviously, it isn’t desirable to always link all the CES converters and the CCS tables to the library but instead, we want to be able to load the needed converters and tables dynamically on demand. This isn’t a problem on "big" machines such as a PC, but it may be very problematical within "small" embedded systems.
Since the CCS tables are just data, it is possible to load them dynamically from external files. The CES converters, on the other hand are algorithms with some code so a dynamic library loading capability is required.
Apart from possible restrictions applied by embedded systems (small RAM for example), Newlib itself has no dynamic library support and therefore, all the CES converters which will ever be used must be linked into the library. However, loading of the dynamic CCS tables is possible and is implemented in the Newlib iconv library. It may be enabled via the Newlib configure script options.
The next design issue is fine-tuning the iconv library configuration. One important ability is for iconv to not link all it’s converters and tables (if dynamic loading is not enabled) but instead, enable only those encodings which are specified at configuration time (see the section about the configure script options).
In addition, the Newlib iconv library configure options distinguish between conversion directions. This means that not only are supported encodings selectable, the conversion direction is as well. For example, if user wants the configuration which allows conversions from UTF-8 to UTF-16 and doesn’t plan using the "UTF-16 to UTF-8" conversions, he or she can enable only this conversion direction (i.e., no "UTF-16 -> UTF-8"-related code will be included) thus, saving some memory (note, that such technique allows to exclude one half of a CCS table from linking which may be big enough).
One more design aspect are the speed- and size- optimized tables. Users can select between them using configure script options. The speed-optimized CCS tables are the same as the size-optimized ones in case of 8-bit CCS (e.g.m KOI8-R), but for 16-bit CCS-es the size-optimized CCS tables may be 1.5 to 2 times less then the speed-optimized ones. On the other hand, conversion with speed tables is several times faster.
Its worth to stress that the new encoding support can’t be dynamically added into an already compiled Newlib library, even if it needs only an additional CCS table and iconv is configured to use the external files with CCS tables (this isn’t the fundamental restriction and the possibility to add new Table-based encoding support dynamically, by means of just adding new .cct file, may be easily added).
Theoretically, the compiled-in CCS tables should be more appropriate for embedded systems than dynamically loaded CCS tables. This is because the compiled-in tables are read-only and can be placed in ROM whereas dynamic loading requires RAM. Moreover, in the current iconv implementation, a distinct copy of the dynamic CCS file is loaded for each opened iconv descriptor even in case of the same encoding. This means, for example, that if two iconv descriptors for "KOI8-R -> UCS-4BE" and "KOI8-R -> UTF-16BE" are opened, two copies of koi8-r .cct file will be loaded (actually, iconv loads only the needed part of these files). On the other hand, in the case of compiled-in CCS tables, there will always be only one copy.
Next: Encoding names, Previous: iconv design decisions, Up: Encoding conversions (iconv.h) [Contents][Index]
To enable an encoding, the –enable-newlib-iconv-encodings configure script option should be used. This option accepts a comma-separated list of encodings that should be enabled. The option enables each encoding in both ("to" and "from") directions.
The --enable-newlib-iconv-from-encodings configure script option enables "from" support for each encoding that was passed to it.
The --enable-newlib-iconv-to-encodings configure script option enables "to" support for each encoding that was passed to it.
Example: if user plans only the "KOI8-R -> UTF-8", "UTF-8 -> ISO-8859-5" and
"KOI8-R -> UCS-2" conversions, the most optimal way (minimal iconv
code and data will be linked) is to configure Newlib with the following
options:
--enable-newlib-iconv-encodings=UTF-8
--enable-newlib-iconv-from-encodings=KOI8-R
--enable-newlib-iconv-to-encodings=UCS-2,ISO-8859-5
which is the same as
--enable-newlib-iconv-from-encodings=KOI8-R,UTF-8
--enable-newlib-iconv-to-encodings=UCS-2,ISO-8859-5,UTF-8
User may also just use the
--enable-newlib-iconv-encodings=KOI8-R,ISO-8859-5,UTF-8,UCS-2
configure script option, but it isn’t so optimal since there will be
some unneeded data and code.
The --enable-newlib-iconv-external-ccs option enables iconv’s capabilities to work with the external CCS files.
The --enable-target-optspace Newlib configure script option also affects the iconv library. If this option is present, the library uses the size optimized CCS tables. This means, that only the size-optimized CCS tables will be linked or, if the --enable-newlib-iconv-external-ccs configure script option was used, the iconv library will load the size-optimized tables. If the --enable-target-optspaceconfigure script option is disabled, the speed-optimized CCS tables are used.
Note: .cct files are searched by iconv_open in the $NLSPATH/iconv_data/ directory. Thus, the NLSPATH environment variable should be set.
Next: CCS tables, Previous: iconv configuration, Up: Encoding conversions (iconv.h) [Contents][Index]
Each encoding has one name and a number of aliases. When
user works with the iconv library (i.e., when the iconv_open call
is used) both name or aliases may be used. The same is when encoding
names are used in configure script options.
Names and aliases may be specified in any case (small or capital letters) and the - symbol is equivalent to the _ symbol.
Internally the Newlib iconv library always converts aliases to names. It also converts names and aliases in the normalized form which means that all capital letters are converted to small letters and the - symbols are converted to _ symbols.
Next: CES converters, Previous: Encoding names, Up: Encoding conversions (iconv.h) [Contents][Index]
The iconv library stores files with CCS tables in the the ccs/ subdirectory. The CCS tables for any CCS may be kept in two forms - in the binary form (.cct files, see the ccs/binary/ subdirectory) and in form of compilable .c source files. The .cct files are only used when the --enable-newlib-iconv-external-ccs configure script option is enabled. The .c files are linked to the Newlib library if the corresponding encoding is enabled.
As stated earlier, the Newlib iconv library performs all conversions through the 32-bit UCS, but the codes which are used in most CCS-es, fit into the first 16-bit subset of the 32-bit UCS set. Thus, in order to make the CCS tables more compact, the 16-bit UCS-2 is used instead of the 32-bit UCS-4.
CCS tables may be 8- or 16-bit wide. 8-bit CCS tables map 8-bit CCS to 16-bit UCS-2 and vice versa while 16-bit CCS tables map 16-bit CCS to 16-bit UCS-2 and vice versa. 8-bit tables are small (in size) while 16-bit tables may be big enough. Because of this, 16-bit CCS tables may be either speed- or size-optimized. Size-optimized CCS tables are smaller then speed-optimized ones, but the conversion process is slower if the size-optimized CCS tables are used. 8-bit CCS tables have only size-optimized variant.
Each CCS table (both speed- and size-optimized) consists of from_ucs and to_ucs subtables. "from_ucs" subtable maps UCS-2 codes to CCS codes, while "to_ucs" subtable maps CCS codes to UCS-2 codes.
Almost all 16-bit CCS tables contain less then 0xFFFF codes and a lot of gaps exist.
In case of 8-bit speed-optimized CCS tables the "to_ucs" subtables format is trivial - it is just the array of 256 16-bit UCS codes. Therefore, an UCS-2 code Y corresponding to a X CCS code is calculates as Y = to_ucs[X].
Obviously, the simplest way to create the "from_ucs" table or the 16-bit "to_ucs" table is to use the huge 16-bit array like in case of the 8-bit "to_ucs" table. But almost all the 16-bit CCS tables contain less then 0xFFFF code maps and this fact may be exploited to reduce the size of the CCS tables.
In this chapter the "UCS-2 -> CCS" 8-bit CCS table format is described. The 16-bit "CCS -> UCS-2" CCS table format is the same, except the mapping direction and the CCS bits number.
In case of the 8-bit speed-optimized table the "from_ucs" subtable corresponds the "from_ucs" array and has the following layout:
from_ucs array:
————————————-
0xFF mapping (2 bytes) (only for
8-bit table).
————————————-
Heading block
————————————-
Block 1
————————————-
Block 2
————————————-
...
————————————-
Block N
————————————-
The 0x0000-0xFFFF 16-bit code range is divided to 256 code subranges. Each subrange is represented by an 256-element block (256 1-byte elements or 256 2-byte element in case of 16-bit CCS table) with elements which are equivalent to the CCS codes of this subrange. If the "UCS-2 -> CCS" mapping has big enough gaps, some blocks will be absent and there will be less then 256 blocks.
Any element number m of the heading block (which contains 256 2-byte elements) corresponds to the m-th 256-element subrange. If the subrange contains some codes, the value of the m-th element of the heading block contains the offset of the corresponding block in the "from_ucs" array. If there is no codes in the subrange, the heading block element contains 0xFFFF.
If there are some gaps in a block, the corresponding block elements have the 0xFF value. If there is an 0xFF code present in the CCS, it’s mapping is defined in the first 2-byte element of the "from_ucs" array.
Having such a table format, the algorithm of searching the CCS code X which corresponds to the UCS-2 code Y is as follows.
As it is stated above, size-optimized tables exist only for 16-bit CCS-es. This is because there is too small difference between the speed-optimized and the size-optimized table sizes in case of 8-bit CCS-es.
Formats of the "to_ucs" and "from_ucs" subtables are equivalent in case of size-optimized tables.
This sections describes the format of the "UCS-2 -> CCS" size-optimized CCS table. The format of "CCS -> UCS-2" table is the same.
The idea of the size-optimized tables is to split the UCS-2 codes ("from" codes) on ranges (range is a number of consecutive UCS-2 codes). Then CCS codes ("to" codes) are stored only for the codes from these ranges. Distinct "from" codes, which have no range (unranged codes, are stored together with the corresponding "to" codes.
The following is the layout of the size-optimized table array:
size_arr array:
————————————-
Ranges number (2 bytes)
————————————-
Unranged codes number (2 bytes)
————————————-
Unranged codes array index (2 bytes)
————————————-
Ranges indexes (triads)
————————————-
Ranges
————————————-
Unranged codes array
————————————-
The Unranged codes array index size_arr section helps to find
the offset of the needed range in the size_arr and has
the following format (triads):
the first code in range, the last code in range, range offset.
The array of these triads is sorted by the firs element, therefore it is possible to quickly find the needed range index.
Each range has the corresponding sub-array containing the "to" codes. These sub-arrays are stored in the place marked as "Ranges" in the layout diagram.
The "Unranged codes array" contains pairs ("from" code, "to" code") for each unranged code. The array of these pairs is sorted by "from" code values, therefore it is possible to find the needed pair quickly.
Note, that each range requires 6 bytes to form its index. If, for example, there are two ranges (1 - 5 and 9 - 10), and one unranged code (7), 12 bytes are needed for two range indexes and 4 bytes for the unranged code (total 16). But it is better to join both ranges as 1 - 10 and mark codes 6 and 8 as absent. In this case, only 6 additional bytes for the range index and 4 bytes to mark codes 6 and 8 as absent are needed (total 10 bytes). This optimization is done in the size-optimized tables. Thus, ranges may contain small gaps. The absent codes in ranges are marked as 0xFFFF.
Note, a pair of "from" codes is stored by means of unranged codes since the number of bytes which are needed to form the range is greater than the number of bytes to store two unranged codes (5 against 4).
The algorithm of searching of the CCS code X which corresponds to the UCS-2 code Y (input) in the "UCS-2 -> CCS" size-optimized table is as follows.
The .c source files for 8-bit CCS tables have "to_ucs" and "from_ucs" speed-optimized tables. The .c source files for 16-bit CCS tables have "to_ucs_speed", "to_ucs_size", "from_ucs_speed" and "from_ucs_size" tables.
When .c files are compiled and used, all the 16-bit and 32-bit values have the native endian format (Big Endian for the BE systems and Little Endian for the LE systems) since they are compile for the system before they are used.
In case of .cct files, which are intended for dynamic CCS tables loading, the CCS tables are stored either in LE or BE format. Since the .cct files are generated by the ’mktbl.pl’ Perl script, it is possible to choose the endianess of the tables. It is also possible to store two copies (both LE and BE) of the CCS tables in one .cct file. The default .cct files (which come with the Newlib sources) have both LE and BE CCS tables. The Newlib iconv library automatically chooses the needed CCS tables (with appropriate endianess).
Note, the .cct files are only used when the --enable-newlib-iconv-external-ccs is used.
The ’mktbl.pl’ script is intended to generate .cct and .c CCS table files from the CCS source files.
The CCS source files are just text files which has one or more colons with CCS <-> UCS-2 codes mapping. To see an example of the CCS table source files see one of them using URL-s which will be given bellow.
The following table describes where the source files for CCS table files provided by the Newlib distribution are located.
| Name | URL |
| big5 | http://www.unicode.org/Public/MAPPINGS/OBSOLETE/EASTASIA/OTHER/BIG5.TXT |
| cns11643_plane1 cns11643_plane14 cns11643_plane2 | http://www.unicode.org/Public/MAPPINGS/OBSOLETE/EASTASIA/OTHER/CNS11643.TXT |
| cp775 cp850 cp852 cp855 cp866 | http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/PC/ |
| iso_8859_1 iso_8859_2 iso_8859_3 iso_8859_4 iso_8859_5 iso_8859_6 iso_8859_7 iso_8859_8 iso_8859_9 iso_8859_10 iso_8859_11 iso_8859_13 iso_8859_14 iso_8859_15 | http://www.unicode.org/Public/MAPPINGS/ISO8859/ |
| iso_ir_111 | http://crl.nmsu.edu/~mleisher/csets/ISOIR111.TXT |
| jis_x0201_1976 jis_x0208_1990 jis_x0212_1990 | http://www.unicode.org/Public/MAPPINGS/OBSOLETE/EASTASIA/JIS/JIS0201.TXT |
| koi8_r | http://www.unicode.org/Public/MAPPINGS/VENDORS/MISC/KOI8-R.TXT |
| koi8_ru | http://crl.nmsu.edu/~mleisher/csets/KOI8RU.TXT |
| koi8_u | http://crl.nmsu.edu/~mleisher/csets/KOI8U.TXT |
| koi8_uni | http://crl.nmsu.edu/~mleisher/csets/KOI8UNI.TXT |
| ksx1001 | http://www.unicode.org/Public/MAPPINGS/OBSOLETE/EASTASIA/KSC/KSX1001.TXT |
| win_1250 win_1251 win_1252 win_1253 win_1254 win_1255 win_1256 win_1257 win_1258 | http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/PC/ |
The CCS source files aren’t distributed with Newlib because of License restrictions in most Unicode.org’s files.
The following are ’mktbl.pl’ options which were used to generate .cct files. Note, to generate CCS tables source files -s option should be added.
For more info about the ’mktbl.pl’ options, see the ’mktbl.pl -h’ output.
It is assumed that CCS codes are 16 or less bits wide. If there are wider CCS codes in the CCS source file, the bits which are higher then 16 defines plane (see the cns11643.txt CCS source file).
Sometimes, it is impossible to map some CCS codes to the 16-bit UCS if, for example, several different CCS codes are mapped to one UCS-2 code or one CCS code is mapped to the pair of UCS-2 codes. In these cases, such CCS codes (lost codes) aren’t just rejected but instead, they are mapped to the default UCS-2 code (which is currently the ? character’s code).
Next: The encodings description file, Previous: CCS tables, Up: Encoding conversions (iconv.h) [Contents][Index]
Similar to the CCS tables, CES converters are also split into "from UCS" and "to UCS" parts. Depending on the iconv library configuration, these parts are enabled or disabled.
The following it the list of CES converters which are currently present in the Newlib iconv library.
Next: How to add new encoding, Previous: CES converters, Up: Encoding conversions (iconv.h) [Contents][Index]
To simplify the process of adding new encodings support allowing to automatically generate a lot of "glue" files.
There is the ’encoding.deps’ file in the lib/ subdirectory which is used to describe encoding’s properties. The ’mkdeps.pl’ Perl script uses ’encoding.deps’ to generates the "glue" files.
The ’encoding.deps’ file is composed of sections, each section consists of entries, each entry contains some encoding/CES/CCS description.
The ’encoding.deps’ file’s syntax is very simple. Currently only two sections are defined: ENCODINGS and CES_DEPENDENCIES.
Each ENCODINGS section’s entry describes one encoding and contains the following information.
Note all names in the ’encoding.deps’ file have to have the normalized form.
Each CES_DEPENDENCIES section’s entry describes dependencies of one CES converted. For example, the euc CES converter depends on the table and the us_ascii CES converter since the euc CES converter uses them. This means, that both table and us_ascii CES converters should be linked if the euc CES converter is enabled.
The CES_DEPENDENCIES section defines the following:
The ’mktbl.pl’ Perl script automatically solves the following tasks.
The ’mktbl.pl’ Perl script is intended to interpret the ’encoding.deps’ file and generates the following files.
_iconv_from_ucs_ces and _iconv_to_ucs_ces) which contain
description of enabled "to UCS" and "from UCS" CES converters and the
names of encodings which are supported by these CES converters.
Next: The locale support interfaces, Previous: The encodings description file, Up: Encoding conversions (iconv.h) [Contents][Index]
At first, the new encoding should be broken down to CCS and CES. Then, the process of adding new encoding is split to the following activities.
In case a new encoding doesn’t fit to the CES/CCS decomposition model or it is desired to add the specialized (non UCS-based) conversion support, the Newlib iconv library code should be upgraded.
Next: Contact, Previous: How to add new encoding, Up: Encoding conversions (iconv.h) [Contents][Index]
The newlib iconv library also has some interface functions (besides the
iconv, iconv_open and iconv_close interfaces) which
are intended for the Locale subsystem. All the locale-related code is
placed in the lib/iconvnls.c file.
The following is the description of the locale-related interfaces:
_iconv_nls_open - opens two iconv descriptors for "CCS ->
wchar_t" and "wchar_t -> CCS" conversions. The normalized CCS name is
passed in the function parameters. The wchar_t characters encoding is
either ucs_2_internal or ucs_4_internal depending on size of
wchar_t.
_iconv_nls_conv - the function is similar to the iconv
functions, but if there is no character in the output encoding which
corresponds to the character in the input encoding, the default
conversion isn’t performed (the iconv function sets such output
characters to the ? symbol and this is the behavior, which is
specified in SUSv3).
_iconv_nls_get_state - returns the current encoding’s shift state
(the mbstate_t object).
_iconv_nls_set_state sets the current encoding’s shift state (the
mbstate_t object).
_iconv_nls_is_stateful - checks whether the encoding is stateful
or stateless.
_iconv_nls_get_mb_cur_max - returns the maximum length (the
maximum bytes number) of the encoding’s characters.
Previous: The locale support interfaces, Up: Encoding conversions (iconv.h) [Contents][Index]
The author of the original BSD iconv library (Alexander Chuguev) no longer supports that code.
Any questions regarding the iconv library may be forwarded to Artem B. Bityuckiy (dedekind@oktetlabs.ru or dedekind@mail.ru) as well as to the public Newlib mailing list.
Next: Variable Argument Lists, Previous: Encoding conversions (iconv.h), Up: The Red Hat newlib C Library [Contents][Index]
Next: Object Size Checking, Up: Overflow Protection [Contents][Index]
Stack Smashing Protection is a compiler feature which emits extra code
to check for stack smashing attacks. It depends on a canary, which is
initialized with the process, and functions for process termination when
an overflow is detected. These are private entry points intended solely
for use by the compiler, and are used when any of the -fstack-protector,
-fstack-protector-all, -fstack-protector-explicit, or
-fstack-protector-strong compiler flags are enabled.
Previous: Stack Smashing Protection, Up: Overflow Protection [Contents][Index]
Object Size Checking is a feature which wraps certain functions with checks
to prevent buffer overflows. These are enabled when compiling with
optimization (-O1 and higher) and _FORTIFY_SOURCE defined
to 1, or for stricter checks, to 2.
The following functions use object size checking to detect buffer overflows when enabled:
String functions:
bcopy memmove strcpy bzero mempcpy strcat explicit_bzero memset strncat memcpy stpcpy strncpy
Wide Character String functions:
fgetws wcrtomb wcsrtombs fgetws_unlocked wcscat wmemcpy mbsnrtowcs wcscpy wmemmove mbsrtowcs wcsncat wmempcpy wcpcpy wcsncpy wmemset wcpncpy wcsnrtombs
Stdio functions:
fgets fread_unlocked sprintf fgets_unlocked gets vsnprintf fread snprintf vsprintf
Stdlib functions:
mbstowcs wcstombs wctomb
System functions:
getcwd read ttyname_r pread readlink
Next: Document Index, Previous: Overflow Protection, Up: The Red Hat newlib C Library [Contents][Index]
The printf family of functions is defined to accept a variable
number of arguments, rather than a fixed argument list. You can define
your own functions with a variable argument list, by using macro
definitions from either stdarg.h (for compatibility with ANSI C)
or from varargs.h (for compatibility with a popular convention
prior to ANSI C).
Next: Traditional macros, varargs.h, Up: Variable Argument Lists [Contents][Index]
In ANSI C, a function has a variable number of arguments when its
parameter list ends in an ellipsis (...). The parameter list
must also include at least one explicitly named argument; that argument
is used to initialize the variable list data structure.
ANSI C defines three macros (va_start, va_arg, and
va_end) to operate on variable argument lists. stdarg.h
also defines a special type to represent variable argument lists: this
type is called va_list.
Synopsis
#include <stdarg.h> void va_start(va_list ap, rightmost);
Description
Use va_start to initialize the variable argument list ap,
so that va_arg can extract values from it. rightmost is
the name of the last explicit argument in the parameter list (the
argument immediately preceding the ellipsis ‘...’ that flags
variable arguments in an ANSI C function header). You can only use
va_start in a function declared using this ellipsis notation
(not, for example, in one of its subfunctions).
Returns
va_start does not return a result.
Portability
ANSI C requires va_start.
Next: Abandon a variable argument list, Previous: Initialize variable argument list, Up: ANSI-standard macros, stdarg.h [Contents][Index]
Synopsis
#include <stdarg.h> type va_arg(va_list ap, type);
Description
va_arg returns the next unprocessed value from a variable
argument list ap (which you must previously create with
va_start). Specify the type for the value as the second parameter
to the macro, type.
You may pass a va_list object ap to a subfunction, and use
va_arg from the subfunction rather than from the function
actually declared with an ellipsis in the header; however, in that case
you may only use va_arg from the subfunction. ANSI C does
not permit extracting successive values from a single variable-argument
list from different levels of the calling stack.
There is no mechanism for testing whether there is actually a next argument available; you might instead pass an argument count (or some other data that implies an argument count) as one of the fixed arguments in your function call.
Returns
va_arg returns the next argument, an object of type type.
Portability
ANSI C requires va_arg.
Previous: Extract a value from argument list, Up: ANSI-standard macros, stdarg.h [Contents][Index]
Synopsis
#include <stdarg.h> void va_end(va_list ap);
Description
Use va_end to declare that your program will not use the variable
argument list ap any further.
Returns
va_end does not return a result.
Portability
ANSI C requires va_end.
Previous: ANSI-standard macros, stdarg.h, Up: Variable Argument Lists [Contents][Index]
If your C compiler predates ANSI C, you may still be able to use variable argument lists using the macros from the varargs.h header file. These macros resemble their ANSI counterparts, but have important differences in usage. In particular, since traditional C has no declaration mechanism for variable argument lists, two additional macros are provided simply for the purpose of defining functions with variable argument lists.
As with stdarg.h, the type va_list is used to hold a data
structure representing a variable argument list.
Synopsis
#include <varargs.h> function(va_alist) va_dcl
Description
To use the varargs.h version of variable argument lists, you must
declare your function with a call to the macro va_alist as its
argument list, and use va_dcl as the declaration. Do not
use a semicolon after va_dcl.
Returns
These macros cannot be used in a context where a return is syntactically
possible.
Portability
va_alist and va_dcl were the most widespread method of
declaring variable argument lists prior to ANSI C.
Next: Extract a value from argument list, Previous: Declare variable arguments, Up: Traditional macros, varargs.h [Contents][Index]
Synopsis
#include <varargs.h> va_list ap; va_start(ap);
Description
With the varargs.h macros, use va_start to initialize a
data structure ap to permit manipulating a variable argument list.
ap must have the type va_alist.
Returns
va_start does not return a result.
Portability
va_start is also defined as a macro in ANSI C, but the
definitions are incompatible; the ANSI version has another parameter
besides ap.
Next: Abandon a variable argument list, Previous: Initialize variable argument list, Up: Traditional macros, varargs.h [Contents][Index]
Synopsis
#include <varargs.h> type va_arg(va_list ap, type);
Description
va_arg returns the next unprocessed value from a variable
argument list ap (which you must previously create with
va_start). Specify the type for the value as the second parameter
to the macro, type.
Returns
va_arg returns the next argument, an object of type type.
Portability
The va_arg defined in varargs.h has the same syntax and
usage as the ANSI C version from stdarg.h.
Previous: Extract a value from argument list, Up: Traditional macros, varargs.h [Contents][Index]
Synopsis
#include <varargs.h> va_end(va_list ap);
Description
Use va_end to declare that your program will not use the variable
argument list ap any further.
Returns
va_end does not return a result.
Portability
The va_end defined in varargs.h has the same syntax and
usage as the ANSI C version from stdarg.h.
Previous: Variable Argument Lists, Up: The Red Hat newlib C Library [Contents][Index]
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