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From: torek@elf.ee.lbl.gov (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: macros and semicolons
Message-ID: <14795@dog.ee.lbl.gov>
Date: 28 Jun 91 17:06:55 GMT
References: <1991Jun24.213932.595@otago.ac.nz> <160662@pyramid.pyramid.com> <6531@goanna.cs.rmit.oz.au> <1991Jun28.134517.5972@nss1.com>
Reply-To: torek@elf.ee.lbl.gov (Chris Torek)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 10
X-Local-Date: Fri, 28 Jun 91 10:06:55 PDT

In article <1991Jun28.134517.5972@nss1.com> mrm@nss1.com
(Michael R. Miller) writes:
>#define swap(x, y)  (x ^= y ^= x ^= y)

See the Frequently Asked Questions.  This macro produces undefined
results because it modifies an object more than once without an
intervening sequence point.
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)
Berkeley, CA		Domain:	torek@ee.lbl.gov