Path: utzoo!utgpu!water!watmath!clyde!rutgers!mit-eddie!uw-beaver!cornell!rochester!udel!gatech!hao!ames!umd5!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.lang.c
Subject: Re: Is NULL == 0 always true?
Keywords: NULL
Message-ID: <7013@brl-smoke.ARPA>
Date: 9 Jan 88 09:57:54 GMT
References: <134@soleil.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 15

In article <134@soleil.UUCP> geigel@soleil.UUCP (Joe Geigel) writes:
> Is NULL always equivalent to the value 0?

NULL is a macro #defined by <stdio.h> and occasionally other headers.
It is whatever it is #defined to be!  However, as we discuss in this
newsgroup about once a year, the ways that it is intended to be used
(as a generic null pointer constant) require that it be #defined to
be just the integer constant 0, in pre-ANSI C, or either 0 or
(void *)0 in ANSI C.  Some implementations currently #define it as
(char *)0, but whoever did that was operating under a misconception.

>        if (ptr = strchr (str,'\')) {

This is, has been, and will continue to be a correct way to test
for a null pointer.  However, '\' is nonportable.