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From: guy@rlgvax.UUCP (Guy Harris)
Newsgroups: net.unix-wizards,net.bugs.4bsd
Subject: Re: Please use NULL instead of 0 whenever you have a pointer!
Message-ID: <1546@rlgvax.UUCP>
Date: Sat, 14-Jan-84 15:18:49 EST
Article-I.D.: rlgvax.1546
Posted: Sat Jan 14 15:18:49 1984
Date-Received: Sun, 15-Jan-84 05:59:52 EST
References: <210@basserva.UUCP> <151@ttds.UUCP>
Organization: CCI Office Systems Group, Reston, VA
Lines: 19

Actually, in <stdio.h> NULL is defined as 0, which is really as it should
be.  So whether you use 0 or NULL makes no difference (unless somebody
made the mistake of defining NULL as "(char *)0"); you still have to
cast it explicitly.  Then again, that's what "lint" is for; it's a good
idea to run "lint" on any program which isn't a quick throw-away or very
small and written by somebody you *know* won't make type errors - on the
other hand, I don't know anybody like that, myself included.

(If NULL were defined as "(char *)0", "lint" would get gastric distress
whenever NULL were passed as a pointer argument to a routine which expected
an "int *" or something like that.  Furthermore, if you tried to assign
"(char *)0" to an "int *" variable, PCC would justifiably complain about
an illegal pointer combination.  C doesn't have the notion of a generic
"null pointer", it has a "null pointer to char" which is distinct from
"null pointer to int" which is distinct from "null pointer to
(struct proc)"....)

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy