Path: utzoo!utgpu!water!watmath!clyde!ima!spdcc!lexicon!rk
From: rk@lexicon.UUCP (Bob Kukura)
Newsgroups: comp.arch
Subject: Re: negative addresses
Message-ID: <268@lexicon.UUCP>
Date: 11 May 88 12:28:01 GMT
References: <2393@uvacs.CS.VIRGINIA.EDU> <9485@apple.Apple.Com>
Organization: Lexicon, Inc., Waltham, MA
Lines: 16
In-reply-to: bcase@Apple.COM's message of 10 May 88 17:57:26 GMT
Posting-Front-End: GNU Emacs 18.41.8 of Thu Feb  4 1988 on fear (berkeley-unix)

From article <9485@apple.Apple.Com> by bcase@Apple.COM (Brian Case):
>In article <2393@uvacs.CS.VIRGINIA.EDU> wulf@uvacs.CS.VIRGINIA.EDU (Bill Wulf) writes:
>>...as far as I can tell, the primary (only?) use
>>of unsigned arithmetic is for address computations.
>
>Yeah, same here, unless it's for some obscure purpose or is supported
>directly by the source language.

Unsigned arithmetic is used in array index calculations all the time.
You only have to check one bound if the first element is at zero and
the index is unsigned.  I'm sure languages like Pascal can use the
condition codes to check for negative indices, but condition codes are
not available to the programmer in C.
-- 
-Bob Kukura		uucp: {husc6,linus,harvard,bbn}!spdcc!lexicon!rk
			phone: (617) 891-6790