Path: utzoo!attcan!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c
Subject: Re: the nil pointer is not zero
Message-ID: <525@taumet.com>
Date: 19 Nov 90 16:33:52 GMT
References: <27636@mimsy.umd.edu> <164@nazgul.UUCP> <14516@smoke.brl.mil> <1990Nov18.024151.19321@ux1.cso.uiuc.edu>
Organization: Taumetric Corporation, San Diego
Lines: 23

mcdonald@aries.scs.uiuc.edu (Doug McDonald) writes:

|The point is that if it were indeed actually all bits zero, in all
|contexts, period, and so that you could not, for example, 
|say,

|char *i;
|int j;
|scanf("%d",&j);
|i = (char *) j;

|and end up with something other than a null pointer if you input 
|0 to the scanf, then there would be a lot less discussion in comp.lang.c.

What in the world are you going to do with a pointer value that you read
from a file?  The only useful information you could get would be to note
whether it was zero, which you hope to equate to a nil pointer.  This
purpose might be better served by using a flag instead: it doesn't purport
to carry more information that it really has, and it doesn't rely on
nil pointers being all-bits-zero.
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com