Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!bobmon
From: bobmon@iuvax.cs.indiana.edu (RAMontante)
Newsgroups: comp.lang.c
Subject: Re: swap(x,y)
Message-ID: <25622@iuvax.cs.indiana.edu>
Date: 7 Sep 89 14:41:09 GMT
Reply-To: bobmon@iuvax.cs.indiana.edu (RAMontante)
Organization: malkaryotic
Lines: 20

jeffrey@algor2.UUCP (Jeffrey Kegler):
-
-B)   #define swap(x,y) {int tmp; tmp = x; y = tmp; x = y; }
-
-Consider
-
-  if (...) swap(x,y);
-  else { do stuff ...; swap(a,b); }
-
-which the Solution A allows, but which won't work with the Solution B,
-unless the first semi-colon is omitted.  The second last semi-colon in
-the above example is misleading, but overwise harmless.


gcc accepts the following:

#define swap(a,b)	({int t; t=(a); (a)=(b); (b)=t;})

and the trailing semicolon should be okay here as it follows a
parenthesized expresssion.