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From: gwyn%brl-vld@sri-unix.UUCP
Newsgroups: net.unix-wizards
Subject: Re:  Please use NULL instead of 0 whenever you have a pointer!
Message-ID: <15527@sri-arpa.UUCP>
Date: Mon, 16-Jan-84 03:46:02 EST
Article-I.D.: sri-arpa.15527
Posted: Mon Jan 16 03:46:02 1984
Date-Received: Wed, 18-Jan-84 07:33:15 EST
Lines: 15

From:      Doug Gwyn (VLD/VMB) <gwyn@brl-vld>

However, zero pointers come in several different sizes in some
implementations of C, with (char *) guaranteed to be the widest.
This means that passing an actual argument of 0 to a function
expecting a pointer may not necessarily work, unless the zero is
explicitly type-cast to the corresponding pointer type.  E.g.,
	func( (struct foo *)0, more_args );
or
	func( (struct foo *)NULL, more_args );
rather than
	func( 0, more_args );
or
	func( NULL, more_args );
if the first formal parameter of foo() is declared a (struct foo *).