Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!agate!web-4a.berkeley.edu!laba-4he
From: laba-4he@web-4a.berkeley.edu (The Cybermat Rider)
Newsgroups: comp.lang.c
Subject: Re: When is a statement an expression?
Message-ID: <23708@agate.BERKELEY.EDU>
Date: 27 Apr 89 23:03:41 GMT
References: <1043@itivax.iti.org> <1127@ptolemy.arc.nasa.gov>
Sender: usenet@agate.BERKELEY.EDU
Organization: University of California, Berkeley
Lines: 42

In article <1127@ptolemy.arc.nasa.gov> raymond@ptolemy.arc.nasa.gov (Eric A. Raymond) writes:
>In article <1043@itivax.iti.org> scs@vax3.iti.org (Steve Simmons) writes:
>>	a = if ( a == 1 )
>>		12 ;
>>	else
>>		14 ;
[....]
>You can accomplish this behavior via the ?: connstruct:
>
>      a = (a ? 12 : 14);
       ^^^^^^^^^^^^^^^^^^
Close, but not quite -- if a is 2, you'll get *12*, not 14.  It should be:

	a = ((a == 1) ? 12 : 14);
>
>Incidently, I beleive the comma operator allows you to approach a
>progn (or is it prog1?):
>
>      a = (x=1, y=2, z=3);	
>
>A is 3 if the last expr is returned (progn-like), otherwise 1
>(prog1-like).  Look it up.

I did.  Sorry, but a is guaranteed to be 3.  To quote K&R 2:

A7.18	Comma Operator

	expression:
		assignment-expression
		expression , assignment-expression

A pair of expressions separated by a comma is evaluated left-to-right, and
the value of the left expression is discarded. [.....]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>-- 
>Eric A. Raymond  (raymond@ptolemy.arc.nasa.gov)
>G7 C7 G7 G#7 G7 G+13 C7 GM7 Am7 Bm7 Bd7 Am7 C7 Do13 G7 C7 G7 D+13: Elmore James

----------------------------------------------------------------------------
Adrian Ho a.k.a. The Cybermat Rider	  University of California, Berkeley
laba-4he@web.berkeley.edu		(WEB Evans, Home of The CS Freakies)
Disclaimer:  Nobody takes me seriously, so is it really necessary?