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From: mcdermot@unmvax.UUCP
Newsgroups: net.lang.c
Subject: NULL pointers
Message-ID: <652@unmvax.UUCP>
Date: Sat, 9-Feb-85 00:57:20 EST
Article-I.D.: unmvax.652
Posted: Sat Feb  9 00:57:20 1985
Date-Received: Sun, 10-Feb-85 05:37:55 EST
Distribution: net
Organization: Univ. of New Mexico, Albuquerque
Lines: 18

The recent discussion on NULL pointers having the value 0 brings to
mind a problem encountered in the days of Version 6: data was loaded
at location 0 sometimes (on a PDP-11/40).  If data can be at 0, then
0 can not be the null pointer if that data is to be referenced.  Our
solution was to make NULL be -1.  This always seemed to be better
than 0 (except that on most machines it means slightly longer code).

I haven't noticed the problem with any current software so I guess
the problem is solved (how?).
--john

-- 

John McDermott			{gatech|ucbvax|convex|pur-ee}!unmvax!mcdermot
Univ of NM			W (505) 277-4650 
Albuquerque, NM 87131		H (505) 255-7796

Merry Christmas from "The Land of Enchantment"