Path: utzoo!utgpu!water!watmath!clyde!bellcore!faline!ulysses!allegra!mit-eddie!husc6!cmcl2!brl-adm!brl-smoke!gwyn
From: gwyn@brl-smoke.UUCP
Newsgroups: comp.lang.c
Subject: Re: "logical" xor
Message-ID: <7046@brl-smoke.ARPA>
Date: 12 Jan 88 00:08:01 GMT
References: <11207@brl-adm.ARPA> <20153@teknowledge-vaxc.ARPA>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 13
Posted: Mon Jan 11 19:08:01 1988

In article <20153@teknowledge-vaxc.ARPA> mkhaw@teknowledge-vaxc.ARPA (Mike Khaw) writes:
>1^0 = 1; 0^0 = 0; 1^1 = 0 => logical xor should mean "does not equal",
>for which C has a perfectly good symbol, "!="

Although C doesn't enforce it, it is good style to maintain a careful
distinction between Boolean expressions and arithmetic expressions.
!= would best be considered an arithmetic operator.  This apart from
the fact that 2 XOR 1 would be 3 arithmetically but 0 as a Boolean
(not that I think one should be treating 2 as a Boolean value!).

By the way, I don't think a logical XOR is important enough to bother
adding to C.  It should be in the next conventional language you
design, however (Ada++?).