Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!decwrl!cookie.dec.com!devine
From: devine@cookie.dec.com (Bob Devine)
Newsgroups: comp.lang.c
Subject: static versus auto initialization
Message-ID: <8901182125.AA06523@decwrl.dec.com>
Date: 18 Jan 89 18:15:00 GMT
Organization: Digital Equipment Corporation
Lines: 24


  Would someone explain to me why the discrepancy between the
uninitialized elements of static and auto arrays?  Someone in
our group asked me a question on this point and the best answer
that I could generate was, in essence, "Cuz D.R. did it for speed".

  The problem looks like this:

        static char abc_static [5] = { 'a', 'b', 'c' };

        main()
        {
            auto char abc_auto [5] = { 'a', 'b', 'c' };
            . . .
        }

  For `abc_static', elements [3] and [4] are guarenteed to be zeroed 
out.  However, for `abc_auto', the same elements are garbage.  

  You can probably see that he initially had the static version and
was relying upon the zeros, so when he moved the array inside a
function he got burned...

Bob Devine