Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!oliveb!ames!fxgrp!ljz
From: ljz@fxgrp.UUCP (Lloyd Zusman, Master Byte Software)
Newsgroups: comp.lang.c
Subject: Re: (So-Called) ANSI C
Message-ID: <194@fxgrp.UUCP>
Date: 8 Jan 88 22:46:29 GMT
References: <4668@pyr.gatech.EDU> <495@xyzzy.UUCP> <9930@mimsy.UUCP> <6996@brl-smoke.ARPA> <10027@ut-sally.UUCP>
Reply-To: fxgrp!ljz@ames.arpa (Lloyd Zusman, Master Byte Software)
Followup-To: <10027@ut-sally.UUCP> nather@ut-sally.UUCP (Ed Nather)
Organization: FX Development Group, Inc., Mountain View, CA
Lines: 48

In article <10027@ut-sally.UUCP> nather@ut-sally.UUCP (Ed Nather) writes:
> ...
> [ regarding the == and = opertors in an 'if' statement ]
> ...
>It isn't a typo.  I use it all the time to assign a value to a variable,
>then test the result.  I find it seriously irritating that Turbo C
>crabs about the construction.  Like everyone else, I have written "="
>when I meant "==" ... just as I have made many bonehead errors in
>writing code.  But I don't blame the compiler, or the langauge, when
>I do.
> ...

With regard to == and = in 'if' statements, here's a handy trick
taught to me by an associate that some of you might find useful if you
don't have a C compiler such as Turbo C that complains about = in 'if'
statements:

When you are comparing a variable to a constant, you probably normally
do it like this:

    if (var == CONST) ...

This can cause difficult-to-find problems if you screw up and write it
like this:

    if (var = CONST) ...

But if instead, you write it like

    if (CONST == var) ...

you won't have the same problem, since the construct

    if (CONST = var) ...

will always generate an error.

Thanks to Robert Johnsen of Saratoga, California, for teaching me this
handy trick.

Sorry if this has already appeared on the net recently.


-------------------------------------------------------------------------
 Lloyd Zusman
 Master Byte Software
 Los Gatos, California	    	    	Internet:   fxgrp!ljz@ames.arpa
 "We take things well in hand."	    	UUCP:	    ...!ames!fxgrp!ljz