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From: ok@goanna.cs.rmit.oz.au (Richard A. O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: TRUE and FALSE
Message-ID: <3686@goanna.cs.rmit.oz.au>
Date: 5 Sep 90 06:09:05 GMT
References: <5398@harrier.ukc.ac.uk>
Organization: Comp Sci, RMIT, Melbourne, Australia
Lines: 31

In article <5398@harrier.ukc.ac.uk>, mtr@ukc.ac.uk (M.T.Russell) writes:
> To the people complaining about `if (x == TRUE)': YOU ONLY USE `TRUE' AND
> `FALSE' FOR ASSIGNMENT AND PARAMETER PASSING.  It's a fairly simple rule.

All of _us_ reading this newsgroup may follow that rule, but as an
empirical observation a lot of people _don't_.  I have seen too many
Pascal programs where people wrote
	x: boolean; ... if x = TRUE then ...
(and in Pascal this _works_) to be sanguine about the programmers in
question learning better when they switch to C.  I have also seen this
kind of code in Algol programs, and if I were reading novice Ada programs
I'm sure I'd see it there.  I _have_ seen it in C code, and it was wrong.

Let's not forget the Lisp Lesson:  there is often something useful you
could return instead of an anonymous "true".  For example, if you are
looking for a character in a string, instead of returning TRUE (it is
there) or FALSE (it isn't) you could return a pointer to if it it's
there or NULL if it isn't.  If you program with that in mind, you really
don't _care_ much about TRUE/FALSE -vs- 1/0, because it's rare that you
have so little to say.
> 	- the `&&', `||' and `!' operators demand bool operands and
> 	  yield a bool result.  The ?: operator demands bool as its
> 	  first operand.  The only other operators that take bool
> 	  operands are `!=', `==' and `&' (address of).

Why should your proposed C variant be more restrictive than Pascal?
In Pascal FALSE < TRUE is allowed, meaningful, and true.
It is also allowed, meaningful, and true in Ada (LRM 3.5.3).

-- 
You can lie with statistics ... but not to a statistician.