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From: ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: Need help in <varargs.h>
Message-ID: <6350@goanna.cs.rmit.oz.au>
Date: 15 Jun 91 06:01:17 GMT
References: <1991Jun12.174326.5390@Veritas.COM>
Organization: Comp Sci, RMIT, Melbourne, Australia
Lines: 35

In article <1991Jun12.174326.5390@Veritas.COM>, tsai@Veritas.COM (Cary Tsai) writes:
> Could you C guru tell me why the third ooprint() stmt causes coredump.
> I must be missing something in ooprint().
> void ooprint(va_alist)
> va_dcl
> {
> 	va_list		ap;
> 	PFV		func;
> 	char		*client;
> 	char		*foo;
> 
> 	va_start(ap);
> 	foo = va_arg(ap, char *);
> 	if ((func = va_arg(ap, PFV)) != (PFV) 0) {
	            ^^^^^^
Note: this function ALWAYS tries to access at least two arguments.

> 	ooprint("ooprint", testFunc1, mess1);
> 	ooprint("ooprint", testFunc2, mess2);
> 	ooprint("ooprint"); /* WHY THIS STMT CAUSES CORE-DUMP? */

Why _does_ that statement cause a core dump?
Well, WHERE IS THE SECOND ARGUMENT?
Failing to supply an argument is not the same as supplying a NULL.
I think you mean
	ooprint("ooprint", (PFV)0);

If the function really is as you have presented it, I don't see why
you're bothering with varargs at all.  It would be simpler just to
pass three arguments every time, and to write the 3rd call as
	ooprint("ooprint", (PFV)0, "");
Better type checking, no worries about varargs -vs- stdargs, &c &c &c.
-- 
Q:  What should I know about quicksort?   A:  That it is *slow*.
Q:  When should I use it?  A:  When you have only 256 words of main storage.