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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: using varargs function to call another varargs function
Message-ID: <6048@brl-smoke.ARPA>
Date: Fri, 3-Jul-87 22:21:09 EDT
Article-I.D.: brl-smok.6048
Posted: Fri Jul  3 22:21:09 1987
Date-Received: Sun, 5-Jul-87 00:16:18 EDT
References: <1332@rosevax.Rosemount.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Distribution: world
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 20

/* example implementation of printf() using varargs */

#include	<varargs.h>

printf( va_alist )	/* params: char * followed by variable arguments */
	va_dcl
	{
	va_list	ap;
	char	*s;			/* for the known parameter */

	va_start( ap );
	s = va_arg( ap, char * );	/* pick up first param */
	vprintf( s, ap );		/* specially-designed function */
	va_end( ap );
	}

NOTE: the function being called (vprintf() here) MUST be designed to
accept a va_list parameter.  Also, be very careful to balance va_start()
with va_end(); these macros may have { and } respectively embedded in them,
which affects their proper use in more complex situations.