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From: jas@rtech.UUCP (Jim Shankland)
Newsgroups: comp.lang.c
Subject: Re: Writing readable code
Message-ID: <980@rtech.UUCP>
Date: Mon, 29-Jun-87 12:40:17 EDT
Article-I.D.: rtech.980
Posted: Mon Jun 29 12:40:17 1987
Date-Received: Sat, 4-Jul-87 22:20:42 EDT
References: <1158@copper.TEK.COM> <6858@auspyr.UUCP> <17171@cca.CCA.COM> <22250@sun.uucp> <17193@cca.CCA.COM> <6034@brl-smoke.ARPA>
Reply-To: jas@rtech.UUCP (Jim Shankland)
Organization: Relational Technology, Alameda CA
Lines: 28

In article <6034@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>In this silly debate, people have been making noises that sound as if
>they thought !p and p!=NULL were equivalent.  They of course have
>opposite meaning, which perhaps helps make the point that one should
>"say what one means" rather than trying to take clever shortcuts.

Good point.  Another example:  I frequently see code written on a VAX
that incorrectly says "if (*p)" instead of "if (p)" or "if (p !=
NULL)".  Granted, inexperienced C programmers are more likely to make
this mistake (then again, staying on the VAX, they never learn better);
I still suggest that it is less error-prone to use NULL for zero-valued
pointers, '\0' for the zero-valued character, and "if (e)" only if e is
CONCEPTUALLY boolean (i.e., it is a variable declared as the typedef
'bool',  or its main operator is a relop, or....).

This is, indeed, a silly debate, and I'm sure we will never come to
consensus; but years of moving other people's C code to dozens of
different machines has absolutely convinced me that being able to say:

    if (integer-or-pointer-valued-expr)

is an error-prone misfeature, and that we'd all be better off programming
as though it didn't exist.
-- 
Jim Shankland
 ..!ihnp4!cpsc6a!\
                  rtech!jas
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