Re: sys/time.h: no more -ansi timercmp ?

[Andreas Jaeger]

address@hidden writes:

>     From: David Morse <address@hidden>
> 
>     Andreas Jaeger <address@hidden> wrote:
> 
>    > Add the appropriate feature test macros (details are in the libc
>    > manual), e.g. _BSD_SOURCE.
> 
>     Ok, read the entry in the manual.  Is the cpp symbol _BSD_SOURCE itself a
>     gnu extension, or part of some portable standard?  I.e. which of these is
>     correct:
> 
>     #ifndef _BSD_SOURCE
>      #define _BSD_SOURCE
>      #include <sys/time.h>
>      #undef _BSD_SOURCE
>     #else
>      #include <sys/time.h>
>     #endif
> 
>     or
> 
>     #ifdef *GLIBC*

That won't work - you need to define _BSD_SOURCE etc before the
inclusion of any other header file!

>      #ifndef _BSD_SOURCE
>       #define _BSD_SOURCE
>       #include <sys/time.h>
>       #undef _BSD_SOURCE
>      #else
>       #include <sys/time.h>
>      #endif
>     #else
>      #include <sys/time.h>
>     #endif
> 
>     where *GLIBC* is some CPP symbol that I don't know yet, that that tells if
>     using glibc.

The right way is:
#define _BSD_SOURCE
#include <...>
> 
> Andreas Jaeger will give the right answer. Let me give the
> wrong one.

I'm not sure if my answer is right and your's wrong - but let's give
it a try ;-).

Some of those _*SOURCE macros are required by the appropriate
standards, like _POSIX_C_SOURCE and _XOPEN_SOURCE.  Others (I'm not
sure) might be a logical GNU extension.  It doesn't hurd to use them.

Andreas
-- 
 Andreas Jaeger
  SuSE Labs address@hidden
   private address@hidden
    http://www.suse.de/~aj