Re: Why no logical XOR operator

Article View: comp.std.c

Article #1690

#1690

From: Doug Gwyn
Date: Thu, 13 Sep 1990 18:07

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In article <1990Sep12.154515.18460@druid.uucp> darcy@druid.uucp (D'Arcy J.M. Cain) writes:
>Does anyone know why C left out the logical XOR operator?

The C standard left it out because it hasn't been part of C,
and it wouldn't address a severe deficiency, which was the only
valid reason for adding functionality during standardization.

The reason that C hasn't had a "logical exclusive-or operator"
is that it would serve no real purpose.  The reason for specific
"logical and" and "logical or" operators is to obtain the short-
circuit effect; obviously a "logical exclusive-or" would not be
able to short-circuit.

If you really feel like you need one, you can define your own:

	#define XOR(a,b) (((a)!=0 ^ (b)!=0) & 1) /* for example */

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.std.c
Subject: Re: Why no logical XOR operator
Message-ID: <13843@smoke.BRL.MIL>
Date: 13 Sep 90 18:07:41 GMT
References: <1990Sep12.154515.18460@druid.uucp>
Followup-To: comp.lang.c
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
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