[FEEDBACK] Issue with fd_set, FD_ZERO, FD_SET, FD_SETSIZE : Cygwin

[Yeo Kai Wei]

Hi All,

Thanks for the help.

I tried adding "#include <sys/select.h>".

However, this is the error message that was returned to me.

$ gcc -o selectStdIn selectStdIn.c
selectStdIn.c:9:10: fatal error: sys/select.h: No such file or directory
  #include <sys/select.h>

Thank you.

On 7/2/2023 4:30 am, gs-cygwin.com@gluelogic.com wrote:
> On Tue, Feb 07, 2023 at 04:25:22AM +0800, Yeo Kai Wei via Cygwin wrote:
>> Hi,
>>
>> I would like to report an issue with Cygwin 3.4.2 on Windows.
>>
>> It doesn't seem to be able to work with  fd_set, FD_ZERO, FD_SET, FD_SETSIZE
>> macros.
>>
>> The code is in italics. The filename was selectStdIn.c. The terminal command
>> used was "gcc -o selectStdIn selectStdIn.c"
>>
>> Thank you.
>>
>> /
>> /
>>
>> /CODE
>> /
>>
>> /#include <stdio.h>//
>> //#include <stdlib.h>//
>> //#include <sys/time.h>//
>> //#include <unistd.h>//
>> / /
>> //void main()//
>> //{//
>> //    fd_set fds; //set of file descriptors//
>> / /
>> //    struct timeval tv;//
>> / /
>> //    int flag;//
>> / /
>> //    char byte;//
>> / /
>> //    FD_ZERO(&fds);//
>> / /
>> //    FD_SET(0, &fds);//
>> / /
>> //    tv.tv_sec = 5;//
>> / /
>> //    tv.tv_usec = 0;//
>> / /
>> //    flag = select(FD_SETSIZE, //
>> //            &fds,//
>> //            NULL,//
>> //            NULL,//
>> //            &tv);//
>> / /
>> //    if(-1 == flag)//
>> //        perror("select error");//
>> //    else if(flag)//
>> //    {//
>> //        read(0,&byte,1);//
>> / /
>> //        puts("data read");//
>> //    }//
>> / /
>> //    if(flag)//
>> //        printf("The byte value is %c\n", byte);//
>> ////
>> //}/
>>
>>
>> TERMINAL COMMANDS
>>
>> $ gcc -o selectStdIn selectStdIn.c
>> selectStdIn.c: In function 'main':
>> selectStdIn.c:8:2: error: unknown type name 'fd_set'; did you mean 'fpos_t'?
>>    fd_set fds; //set of file descriptors
>>    ^~~~~~
>>    fpos_t
>> selectStdIn.c:16:2: warning: implicit declaration of function 'FD_ZERO'
>> [-Wimpli
>> cit-function-declaration]
>>    FD_ZERO(&fds);
>>    ^~~~~~~
>> selectStdIn.c:18:2: warning: implicit declaration of function 'FD_SET'
>> [-Wimplic
>> it-function-declaration]
>>    FD_SET(0, &fds);
>>    ^~~~~~
>> selectStdIn.c:24:9: warning: implicit declaration of function 'select'; did
>> you
>> mean 'sleep'? [-Wimplicit-function-declaration]
>>    flag = select(FD_SETSIZE,
>>           ^~~~~~
>>           sleep
>> selectStdIn.c:24:16: error: 'FD_SETSIZE' undeclared (first use in this
>> function)
>>    flag = select(FD_SETSIZE,
>>                  ^~~~~~~~~~
>> selectStdIn.c:24:16: note: each undeclared identifier is reported only once
>> for
>> each function it appears in
> $ man select
>
> #include <sys/select.h>