From:	Radical DOT NetSurfer AT delorie DOT com
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: HELP: S_ISDIR() ?????
Date:	Tue, 20 Nov 2001 19:59:10 -0500
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On 20 Nov 2001 19:18:07 GMT, Hans-Bernhard Broeker
<broeker AT physik DOT rwth-aachen DOT de> wrote:

>Radical wrote:
[[snippity snip]]
>__DJGPP__ is defined *only* on DJGPP, __GNUC__ is defined on lots of
>other platforms.  If and only if you know that a particular feature is
>common to all versions of GNU CC, you should use __GNUC__.
>
>Best practice usually is to use neither of the two, but rather use
>GNU's "autoconf" to test for the exact features themselves, not the
>platform they run on.  Then you can write things like #if
>HAVE_SYS_STAT_H or #if HAVE_SNPRINTF and so on.

I've seen that done, too.

>In the original case at hand, you'ld write
>
>#ifndef S_ISDIR 
># if defined(S_IFDIR) && defined(S_IFMT)
>#  define S_ISDIR(m) ((m & S_IFMT) == S_IFDIR)
># else
>#  error "no definition of S_ISDIR!"
>#endif

very interesting

>and be done with it.
>
>> in that someone who wants to compile for Linux GCC and not just
>> MSDOS/DJGPP, is GNUC acceptable?
>
>Probably no. You don't know where else GNU CC is used.

Thanks all.

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