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From: guy@sun.uucp (Guy Harris)
Newsgroups: net.lang.c
Subject: Re: RE: if(p)
Message-ID: <2902@sun.uucp>
Date: Thu, 17-Oct-85 05:22:47 EDT
Article-I.D.: sun.2902
Posted: Thu Oct 17 05:22:47 1985
Date-Received: Sat, 19-Oct-85 05:43:23 EDT
References: <1671@brl-tgr.UUCP> <30000017@ISM780.UUCP> <292@graffiti.UUCP>
Organization: Sun Microsystems, Inc.
Lines: 12

> What's wrong with this? It's identical to "if(p==(foo *)i)" according to the
> default expression evaluation rules. Any special meaning of 0 should be
> handled in the evaluation of (foo *)i.

No, it shouldn't.  According to K&R, the rules for conversion between
pointers and integers are machine-dependent but are supposed to be
"unsurprising".  I'd be surprised as hell if, assuming a null pointer had
some value other than all zero bits, this conversion produced a null pointer
if i is zero.  K&R takes great pains to insist that the interpretation of 0
as a null pointer is only to be taken if the 0 is a *constant* 0.

	Guy Harris