Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ames!think!redsox!campbell
From: campbell@redsox.bsw.com (Larry Campbell)
Newsgroups: comp.lang.c
Subject: Re: use of if (!cptr) and if (cptr), where cptr is a *
Keywords: * != int
Message-ID: <803@redsox.bsw.com>
Date: 18 Jul 89 23:42:35 GMT
References: <10099@mpx2.mpx.com>
Reply-To: campbell@redsox.UUCP (Larry Campbell)
Organization: The Boston Software Works, Inc.
Lines: 22

We use macros called NIL and NEW:

    #define NIL(type) ((type) 0)
    #define NEW(type) ((type *) malloc(sizeof(type)))

We also use typedefs to save typing and centralize type information,
so the malloc example looks like this:

    typedef struct foo FOO;

    FOO *p;

    p = NEW(FOO);
    if (p == NIL(FOO *))
	error();

I think this makes it pleasingly clear that you're testing for an invalid
pointer, rather than the quantity zero.
-- 
Larry Campbell                          The Boston Software Works, Inc.
campbell@bsw.com                        120 Fulton Street
wjh12!redsox!campbell                   Boston, MA 02146