Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: effect of free()
Message-ID: <19488@mimsy.UUCP>
Date: 9 Sep 89 04:03:59 GMT
References: <319@cubmol.BIO.COLUMBIA.EDU> <3756@buengc.BU.EDU> <247@bbxeng.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 28

In article <247@bbxeng.UUCP> scott@bbxeng.UUCP (Engineering) writes:
>In other words - you cannot even *test* a pointer unless you are *sure*
>there is a valid address in it.

More or less.

>I don't think so.

You could send comments to the next ANSI C standards committee asking that
this be changed.

>Is NULL some kind of special exception?

Yes.  Nil pointers have always been special exceptions on many machines.

>Before we waste anymore bandwidth with this topic,

Too late.

>does anybody actually know a specific architecture and C compiler combination
>that would cause a problem on a pointer compare?

No, no one knows of any such combination.  It is highly unlikely that
any such combination exists, or ever would be written, although I did
describe how to construct one quite recently.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris