Path: utzoo!attcan!uunet!wuarchive!decwrl!sun-barr!newstop!sun!boise.Eng.Sun.COM!wsb
From: wsb@boise.Eng.Sun.COM (Walt Brainerd)
Newsgroups: comp.lang.fortran
Subject: Re: Side effects in boolean expressions
Summary: It is legal
Message-ID: <140684@sun.Eng.Sun.COM>
Date: 15 Aug 90 15:33:26 GMT
References: <2022@key.COM> <59110@lanl.gov> <2041@key.COM>
Sender: news@sun.Eng.Sun.COM
Lines: 15

In article <2041@key.COM>, sjc@key.COM (Steve Correll) writes:
> ... the C code is legal and its behavior predictable; the Fortran is neither:
>                                                       ^^^^^^^^^^^^^^^^^^^^^^
> 	if ((x < 0.0) || (sqrt(x) < 10.0)) ...
> 	IF ((X .LT. 0.) .OR. (SQRT(X) .LT. 10.0)) ...
> 
The Fortran code certainly is legal.  The main point is that the _result_
is predictable; how the result is obtained is not, which is exactly the
point of optimization.  The difference is when you rely on function
side effects, important in C, but never should be done in Fortran.
--
Walt Brainerd        Sun Microsystems, Inc.
wsb@eng.sun.com      MS MTV 5-40
                     Mountain View, CA 94043
                     415/336-5991