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Path: utzoo!utcsri!greg
From: greg@utcsri.UUCP (Gregory Smith)
Newsgroups: net.lang.c
Subject: Re: unary +
Message-ID: <2318@utcsri.UUCP>
Date: Thu, 13-Mar-86 13:41:03 EST
Article-I.D.: utcsri.2318
Posted: Thu Mar 13 13:41:03 1986
Date-Received: Thu, 13-Mar-86 13:48:25 EST
References: <1227@mtx5a.UUCP> <1223@mit-eddie.MIT.EDU> <1147@lsuc.UUCP>
Reply-To: greg@utcsri.UUCP (Gregory Smith)
Distribution: net
Organization: CSRI, University of Toronto
Lines: 23
Summary: 

In article <1147@lsuc.UUCP> msb@lsuc.UUCP (Mark Brader) writes:
>
>People who don't think (a+b)+c, a+(b+c), and a+b+c should be
>interchangeable with respect to optimization -- as they are and
>will continue to be -- should consider this toy example:
>
>	#define  C_TO_F(temp)		((temp)*1.8 + 32)
>	#define  JUST_ABOVE(temp)	((temp) + epsilon) /* extern epsilon */
>	#define  ROUND(real)		((long) .5 + (real))
>
>	scanf ("%d", &melt_pt);
>	desired_f_temp = ROUND (JUST_ABOVE (C_TO_F (melt_pt)));
>
>There are, of course, NO unnecessary parentheses in the example*.
[example deleted, illustrating why C should be allowed to ignore ()'s in
evaluating expressions]
-But- ROUND(real) should be ((long)(.5+(real))). Casts are more bindish than
+. So the example carries evan more weight.

-- 
"So this is it. We're going to die."	- Arthur Dent
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Greg Smith     University of Toronto       ..!decvax!utzoo!utcsri!greg