Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!btr!mips!ultra!jerbil
From: jerbil@ultra.com (Joseph Beckenbach {Adapter Software Release Engr})
Newsgroups: comp.lang.c
Subject: Re: Portable XOR
Message-ID: <1991Apr19.162526.6742@ultra.com>
Date: 19 Apr 91 16:25:26 GMT
References: <157@revcan.UUCP> <1991Apr18.161333.3463@ultra.com>
Organization: Ultra Network Technologies
Lines: 22


	Following up my own article here, and apologies for missed names:

>	In <157@revcan.UUCP> darren@revcan.UUCP (Darren Morbey) writes,
>asking for a macro returning XOR of its arguments, evaluating once and
>only once.  I've not worked out a more elegant solution for my toolbag,

	... but I've had a light flurry of mail with comments, including
one from the Netherlands pointing out that XOR(a,XOR(b,c)) would fail using
my implementation.  Serves me right for reusing old code without doing a
double-check of other things! :-)

	Another sent me the macro
#define XOR(o,_) ((o)?!(_):(_))
which "does the right thing".  Another macro for toolbox.h :-)

		Joseph Beckenbach
		journeyman programmer
		(still working towards craftsman status)
-- 
Joseph Beckenbach	jerbil@ultra.com		VEGGIES FOREVER!
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