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From: marv@ism780.UUCP
Newsgroups: comp.lang.c
Subject: Re: Query: Implementation with non-zero NULL
Message-ID: <724@ism780.UUCP>
Date: Tue, 2-Jun-87 21:32:15 EDT
Article-I.D.: ism780.724
Posted: Tue Jun  2 21:32:15 1987
Date-Received: Sat, 6-Jun-87 06:28:38 EDT
References: <158@delftcc.UUCP> <1070@viper.Lynx.MN.ORG>
Reply-To: marv@ISM780.UUCP (Marvin Rubenstein)
Organization: Interactive Systems Corp., Santa Monica, CA
Lines: 27

>  If, you're refering to an initialized static, it's whatever you
>specify.  If, on the other hand, you're refering to an UN-initialized
>static pointer, the answer is a resounding "Neither!"....  An un-
>initialized variable is just that.  It can initialy hold literaly
>-any- value that variable can possibly hold.  You should never assume
>anything about any variable until you've set it.
>John Stanley (john@viper.UUCP)
>Software Consultant - DynaSoft Systems
>UUCP: ...{amdahl,ihnp4,rutgers}!{meccts,dayton}!viper!john

K&R does not seem to agree with the above. On page 198 one reads:

   "Static and external variables which are not initialized are
   guaranteed to start off as 0: automatic and register variables
   which are not initialized are guaranteed to start of as garbage."

Note that the ascii character '0' appearing in a C source program has a
context dependent meaning.  It can represent either the integer constant
that falls between -1 and +1 or it can represent a constant pointer that
points to no object.  With this in mind I take the above quote to mean that
all uninitalized (static or external) variables that are numbers will start
out with the value zero and all uninitialized variables that are pointers
start out pointing to no object.  I believe this is all inclusive since the
only primative types in C are pointers and numbers (with various ranges and
scalings).

      Marv Rubinstein -- Interactive Systems