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From: mjl@ritcv.UUCP (Mike Lutz)
Newsgroups: net.lang.c
Subject: Re: SIZEOF
Message-ID: <1499@ritcv.UUCP>
Date: Mon, 28-Jan-85 17:41:23 EST
Article-I.D.: ritcv.1499
Posted: Mon Jan 28 17:41:23 1985
Date-Received: Wed, 30-Jan-85 08:27:45 EST
References: <347@ecr.UUCP> <393@rlgvax.UUCP>
Organization: Rochester Institute of Technology, Rochester, NY
Lines: 28

> OK.  Everybody take a deep breath and repeat after me:
> 
> THER IS NO ONE NULL ADDRESS CONSTANT IN C!
> 
> There is no such thing as a generic "pointer" in C.

Guy's right, of course.  For those who want null pointers of various
types, might I suggest the following macro:

/*
 * Make a Null Pointer for objects of type 't'
 */

#define NullPtr(t)	( ((t) *) 0 )

This permits code like:

	execl( "/bin/foo", "foo", "bar", NullPtr(char) ) ;

This can be quickly fixed for those who object to creating pointers to
objects of type 't' but want Null pointers for (pointer) type t.

With a bit of imagination, you can create macros to allocate & free
objects of type 't' in a type safe fashion, using malloc/calloc/free.
-- 
Mike Lutz	Rochester Institute of Technology, Rochester NY
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