Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ames!lll-winken!uunet!mcrware!jejones
From: jejones@mcrware.UUCP (James Jones)
Newsgroups: comp.lang.c
Subject: Re: Another silly question
Summary: is + really associative when pointers are involved?
Keywords: pointers, canonical counterexample
Message-ID: <1176@mcrware.UUCP>
Date: 18 May 89 14:52:21 GMT
References: <17812@cup.portal.com> <2336@Portia.Stanford.EDU> <25671@amdcad.AMD.COM>
Reply-To: jejones@mcrware.UUCP (James Jones)
Distribution: usa
Organization: Microware Systems Corp., Des Moines, Iowa
Lines: 17

A message asserts that surely

	(p + 3) + 5 == p + (3 + 5)

where p is a pointer, and so it is, but...in general, it might not be. 
We turn once again to the canonical counterexample, segmented
architectures, where it's not clear that

	(p - 5) + 6 == p + (-5 + 6)

since p - 5 might fall off the end of the segment, and after that, all
bets are likely to be off.

That said, I hasten to add that I agree that p + i == i + p; any bogosity
arising will arise no matter what order is used.

	James Jones