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From: dant@tekla.TEK.COM (Dan Tilque;1893;92-789;LP=A;608C)
Newsgroups: comp.lang.c
Subject: Re: Writing readable code
Message-ID: <1941@zeus.TEK.COM>
Date: Tue, 30-Jun-87 03:43:53 EDT
Article-I.D.: zeus.1941
Posted: Tue Jun 30 03:43:53 1987
Date-Received: Sat, 4-Jul-87 22:49:37 EDT
References: <13008@topaz.rutgers.edu>
Sender: rogers@zeus.TEK.COM
Reply-To: dant@tekla.UUCP (Dan Tilque)
Organization: First National Security Trust Bar and Grill
Lines: 43

Ron Natalie writes:
>I have always wondered why people think NULL is more mnemonic than 0.

NULL is more mneumonic than 0 because it's easy to confuse 0 (zero) with
the letter O.  On many printers and some terminals it's impossible to
tell them apart without close comparison with a known zero.  Since it's
bad form to use a variable named O, and the compile will give a warning
if you use an undeclared variable, this may not be a problem.  However,
I suspect that some of the early compilers did not give a warning and
just defaulted the letter O to an int.  I know this is (was?) a common
problem in FORTRAN.  

>	I also wonder about people who define TRUE to be any
>thing, since it leads to things like
>	if( bool == TRUE )
>which is different than
>	if(!bool)

I thought that TRUE and FALSE should be:

#define FALSE 0
#define TRUE !FALSE

With these #defines the above two statements are equivalent.
>
>Generally, I use !p when I'm dealing with things that are supposed
>boolean values like
>
>	if(!isdigit(c))

It's often easy to miss a single character (especially one that doesn't
stand out like the "!") when quickly scanning code.

	if (isdigit(c) == TRUE)

will compile to the same object code on almost every compiler and is easier
to grasp immediately.  The fact that it's positive logic also makes it
easier.


---
Dan Tilque
dant@tekla.tek.com