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From: franka@mmintl.UUCP (Frank Adams)
Newsgroups: net.lang.c
Subject: Re: More extensions to C (was: Boolean Operators Slighted in C)
Message-ID: <1483@mmintl.UUCP>
Date: Tue, 20-May-86 18:54:02 EDT
Article-I.D.: mmintl.1483
Posted: Tue May 20 18:54:02 1986
Date-Received: Fri, 23-May-86 23:56:24 EDT
References: <2741@utcsri.UUCP> <826@bentley.UUCP>
Reply-To: franka@mmintl.UUCP (Frank Adams)
Organization: Multimate International, E. Hartford, CT
Lines: 21

In article <826@bentley.UUCP> kwh@bentley.UUCP writes:
>In article <2741@utcsri.UUCP> greg@utcsri.UUCP writes:
>>In article <602@brl-smoke.ARPA> rbj@icst-cmr (Root Boy Jim) writes:
>>>3) Exchange operator. ...
>>
>>Good stuff. Even machines without an EXG can use a scratch register, which
>>is better than using a user-supplied temp.
>
>This could be considered a special case of my ",," operator: to exchange x
>and y, write "x = (y ,, (y = x))".

I would prefer a syntax like "{x, y} = {y, x};"  It's more readable.

(BTW, a really good optimizing compiler can optimize out the temporary.  I'm
not fully up on what optimizers are doing these days, but I doubt that there
are many compilers which do this.  Optimizing it out is easier if it is
declared locally ("{int temp = x; x = y; y = temp;}") instead of being
declared at the top of the routine.)

Frank Adams                           ihnp4!philabs!pwa-b!mmintl!franka
Multimate International    52 Oakland Ave North    E. Hartford, CT 06108