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From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: `va_dcl' macro question
Message-ID: <9571@smoke.BRL.MIL>
Date: 2 Feb 89 23:39:42 GMT
References: <1964@kappl.cs.vu.nl> <9507@smoke.BRL.MIL> <991@ubu.warwick.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 49

In article <991@ubu.warwick.UUCP> geoff@emerald.UUCP (Geoff Rimmer) writes:
>All I know about variable arguments in ANSI C is how to do prototypes,
>and define the functions.  However, I don't know how to read each of
>the arguments passed to the function.  Could someone email/post a
>simple function that will take a variable number of strings, and then
>print them to stdout one at a time.
>i.e.
>	void print_strings (char *str, ...)
>	{
>	...
>	}

Well, there has to be some way to tell when the argument list is
exhausted, which you didn't specify.  Let's assume that a null pointer
marks the end of the list.  Then here is how I would implement this:

#include	<stdio.h>
#if __STDC__
#include	<stdarg.h>
#else
#include	<varargs.h>
#define	const	/* nothing */
#endif

#if __STDC__
void					/* DESIGN BOTCH: should return status */
print_strings( register const char *str, ... )
#else
void
print_strings( va_alist )
	va_dcl
#endif
	{
#if !__STDC__
	register const char	*str;
#endif
	va_list		ap;

#if __STDC__
	va_start( ap, str );
#else
	va_start( ap );
	str = va_arg( ap, const char * );
#endif
	for ( ; str != NULL; str = va_arg( ap, const char * ) )
		(void)fputs( str, stdout );

	va_end( ap );
	}