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From: rokicki@polya.Stanford.EDU (Tomas G. Rokicki)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Lattice 5.04 problem with free()
Message-ID: <12765@polya.Stanford.EDU>
Date: 30 Oct 89 22:32:55 GMT
References: <36769@srcsip.UUCP> <37167@lll-winken.LLNL.GOV> <36899@srcsip.UUCP>
Organization: Computer Science Department, Stanford University
Lines: 22

carpent@SRC.Honeywell.COM (Todd Carpenter) writes:
> As long as we are on the subject of Lattice, why doesn't this macro seem to
> work?  (I'm rather new to macrodom, so this is probably a silly one) I
> have some terribly long nasty expressions that need to be squared, and
> SQR(moocow) never returns what I expect:
> 
> #define SQR(x) (x*x)

Well, imagine what happens when you try to SQR(a+b).  You get

   a+b*a+b

which doesn't parse as you intended.  The solution is to change the
macro definition to

#define SQR(x) ((x)*(x))

In general, when defining expression macros, always surround each occurence
of a parameter with a pair of parentheses, and surround the entire expression
with another pair of parentheses, to make sure you get the precedences correct.

-tom