Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!cs.utexas.edu!uunet!pilchuck!dataio!bright
From: bright@Data-IO.COM (Walter Bright)
Newsgroups: comp.lang.c
Subject: Re: va_list used in <stdio.h>
Keywords: va_list, X3J11, vfprintf
Message-ID: <2095@dataio.Data-IO.COM>
Date: 14 Aug 89 19:13:23 GMT
References: <1140@midgard.Midgard.MN.ORG>
Reply-To: bright@dataio.Data-IO.COM (Walter Bright)
Organization: Data I/O Corporation; Redmond, WA
Lines: 30

In article <1140@midgard.Midgard.MN.ORG> dal@midgard.Midgard.MN.ORG (Dale Schumacher) writes:
<I'm working on the header files for a PD LIBC implementation with the
<goal that it be as close as possible to X3J11 and POSIX conformance.
<I'm working from the May 13, 1988 draft of the C pANS.

Finally! Instead of wasting energy worrying about the GNU copyright,
you've got the right idea! Best of luck to you!

<In the <stdio.h> header file, the v[fs]printf() function prototypes
<use the va_list type, but va_list is not defined anywhere in <stdio.h>.

The trick to note is that <stdarg.h> is required for any *user* code that
uses variable argument lists. Since <stdio.h> is supplied by the *vendor*,
the problem can be solved in one of two ways,

1. In stdio.h, include the lines:
	#ifndef __STDARG_H		/* #define'd by stdarg.h	*/
	#include <stdarg.h>		/* get definition of va_list	*/
	#endif
   (As has been discussed here before, using 'wrappers' like this means
    that order dependent #include's can be #include'd in any order
    without a problem.)

2. As the compiler vendor, we *know* what va_list is, so we simply prototype
   vprintf and friends as:
	int vprintf(const char *,char *);
   instead of:
	int vprintf(const char *,va_list);

I use 2. because it compiles faster.