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From: joe@petsd.UUCP (Joe Orost)
Newsgroups: net.lang.c
Subject: Re: Standard extensions (logical exclusive or)
Message-ID: <374@petsd.UUCP>
Date: Tue, 6-Nov-84 08:38:09 EST
Article-I.D.: petsd.374
Posted: Tue Nov  6 08:38:09 1984
Date-Received: Thu, 8-Nov-84 01:21:26 EST
References: <> <352@digi-g.UUCP>, <1442@pucc-h>
Organization: Perkin-Elmer DSG, Tinton Falls, N.J.
Lines: 29

<>
David L Stevens says:

>	The "opop" syntax is for allowing short circuit evaluation of
>boolean expressions. Thus && is there so that C can allow the programmer
>to optimize, where apropriate. Exclusive Or, on the other hand, requires
>that both operands be evaluated, so ^^ has no place.
>	Since boolean expressions evaluate to 1 or 0, bitwise operations
>perform the same function as a non-short-circuit evaluation, and so &
>does it all. I don't see where you lose by using just ^.
>	Of course, tese are all my opinions about the reasoning behind it,
>since they didn't ask me.

I disagree.  The bitwise operators operate on every bit of their arguments,
whereas the logical operators operate on zero -vs- non-zero.  Therefore, i^j
is not the same as i^^j.  i^^j is equivalent to:
	i?(j?0:1):(j?1:0)
which is only the same as i^j when i and j are 0 or 1.

Therefore, I vote for the ^^ operator.

					regards,
					joe

--
Full-Name:  Joseph M. Orost
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