Path: utzoo!attcan!uunet!ateng!chip
From: chip@ateng.ateng.com (Chip Salzenberg)
Newsgroups: comp.lang.c
Subject: Re: Variadic functions
Message-ID: <1988Nov12.165027.2756@ateng.ateng.com>
Date: 12 Nov 88 21:50:26 GMT
References: <434@tutor.UUCP> <225800083@uxe.cso.uiuc.edu> <2774@ingr.UUCP>
Organization: A T Engineering, Tampa, FL
Lines: 26


    WARNING -- NULL ALERT.
    If you understand NULL pointers, skip this article.

According to crossgl@ingr.UUCP (Gordon Cross):
>   Wouldn't it be much nicer to be able to call the
>   function with the single line
>
>        yourfunction ("arg1", "arg2", ... , 0);

Correct ways to code this function call would be:

	yourfunction ("arg1", "arg2", ... , (char *) 0);
or
	yourfunction ("arg1", "arg2", ... , (char *) NULL);

The reason?  Neither uncasted 0 nor uncasted NULL [1] is acceptable as an
actual function parameter of any pointer type.  (Except in the presence
of a function prototype, of course; but this is a variadic function
we're discussing, so prototypes are almost irrelevant.)

[1]   According to K&R and the dpANS, "#define NULL 0" is permitted.
-- 
Chip Salzenberg             <chip@ateng.com> or <uunet!ateng!chip>
A T Engineering             Me?  Speak for my company?  Surely you jest!
	   Beware of programmers carrying screwdrivers.