Path: utzoo!utgpu!water!watmath!clyde!bellcore!faline!ulysses!allegra!mit-eddie!husc6!ut-sally!ut-emx!dlnash
From: dlnash@ut-emx.UUCP
Newsgroups: comp.lang.c
Subject: Re: "logical" xor
Message-ID: <475@ut-emx.UUCP>
Date: 11 Jan 88 22:55:15 GMT
References: <11207@brl-adm.ARPA> <20153@teknowledge-vaxc.ARPA>
Organization: The University of Texas at Austin, Austin, Texas
Lines: 20
Posted: Mon Jan 11 17:55:15 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, "!="
> 

Yes, but "logically" speaking, 1 == 2, since both are non-zero and hence
are both true.  Therefore 1 ^^ 2 should be false, but 1 != 2 is true. 
If you are dealing with non-canonical true-false values, this will hurt
you.  Of course, you can always use !x != !y to translate x and y into
canonical true-false values (or !!x != !!y if you want to be picky), but
that just makes things a little bit harder to understand. 


				Don Nash

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