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Re: gcc4[1.7] printf treats differently a string constant and a character array

Eric Blake on Dec 2009 06:41:33 wrote:

>According to Andy Koppe on 12/29/2009 6:30 AM:
>>> Remember, POSIX states that any use in a character context of bytes with
>>> the 8th-bit set is specifically undefined in the C locale (whether that
>>> C.ASCII or C.UTF-8).
>> I very much disagree with that. C.ASCII and C.UTF-8 are different
>> locales from plain "C", and the whole point of the explicitly stated
>> charset is to define the meaning of bytes beyond 7-bit ASCII.

>Point taken: an explicit "C.UTF-8" is a request of a specific charset
>along with C semantics (such as no translation of output messages,
>posix-mandated formatting for time and money, ...), but because the
>charset is explicit, the use of 8-bit bytes is well-defined in our
>implementation (and since POSIX does not specify C.UTF-8, you've already
>left the realm of portability and gone into implementation-defined).

>But my point remains: an explicit "C" is specified to be charset-agnostic,
>so a portable program requesting "C" should not be expecting any
>particular behavior of 8-bit bytes in character contexts.  Programs that
>use LC_ALL=C to try to get 8-bit transparency from character contexts are
>flat-out non-portable.  They get other well-defined benefits on 8-bit
>bytes (such as sorting by strcmp instead of strcoll, fixed-format
>messages, ...), but only insofar as those 8-bit bytes are in byte contexts
>rather than character contexts.

Some comments:
1- I think that printf(string_constant) and printf(char_array) should give
the same
output in any circumstance.
2- In absence of a call to setlocale printf((string_constant) writes
according to 
the locale of the environment, but  printf(char_array)  does not, even
though  it is
 affected by the locale of the environment.
3- I think that a program that was written for locale=C should work without
if the locale in the environment is any of the one-byte characters ones.
4- I think that a plain C (8-bit transparent) locale should be available,
even if it
is not the default one.


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