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From: andree@uokvax.UUCP
Newsgroups: net.arch
Subject: Re: Re: Complement Arithmetic - (nf)
Message-ID: <5448@uiucdcs.UUCP>
Date: Tue, 7-Feb-84 23:42:55 EST
Article-I.D.: uiucdcs.5448
Posted: Tue Feb  7 23:42:55 1984
Date-Received: Fri, 10-Feb-84 01:42:35 EST
Lines: 23

#R:burdvax:-142500:uokvax:9900007:000:865
uokvax!andree    Feb  5 04:15:00 1984

/***** uokvax:net.arch / kobold!tjt /  5:43 pm  Feb  3, 1984 */
Mike Andree (..!uokvax!andree) has suggested using "-0" on a
one's-complement machine to represent an illegal value for
uninitialized variables.  He was hoping that this would result in no
extra (software) cost.

Unfortunately, TANSTAAFL: somebody has to initialize those
uninitialized variables with the illegal value.
-- 
	Tom Teixeira,  Massachusetts Computer Corporation.  Westford MA
	...!{ihnp4,harpo,decvax}!masscomp!tjt   (617) 692-6200 x275
/* ---------- */

Somebody, somewhere had to initalize them anyway :-). I was actually
refering to runtime costs - you don't have to generate code to test for
the illegal value before each statement. At least one compiler (the
Waterloo Fortran V) does this now. It's a good idea, but the cost!
[If you're interested, the value is 2 * '    '.]