Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!bu-cs!buengc!bph
From: bph@buengc.BU.EDU (Blair P. Houghton)
Newsgroups: comp.lang.c
Subject: Re: Definition of boolean type
Message-ID: <2113@buengc.BU.EDU>
Date: 13 Feb 89 00:32:13 GMT
References: <10@dbase.UUCP> <9609@smoke.BRL.MIL> <3645@arcturus> <15906@mimsy.UUCP> <27989@ucbvax.BERKELEY.EDU>
Reply-To: bph@buengc.bu.edu (Blair P. Houghton)
Followup-To: comp.lang.c
Organization: Boston Univ. Col. of Eng.
Lines: 21

In article <27989@ucbvax.BERKELEY.EDU> jas@ernie.Berkeley.EDU.UUCP (Jim Shankland) writes:
>
>I agree with Karl Heuer:  C would have benefited from a built-in boolean
>type.  As is, conscientious programmers will avoid type punning between
>values that are conceptually boolean with those that are conceptually
>integers (though as far as C is concerned, of course they're both integers.)

Low-sophistication point-of-interest, approx. 20 mills in value:

You can be conscientious if, when unsure of the return value, and you _like_
having true==1 and false==0, then say 

	boolfoo = !!expr_returning_funny_bools;

which, according to my KnR, should never ever give any boolfoo other
than 0 or 1, even if the expr has a dozen different values for true.

(See the description of the '!' op.  I think it's around page 187 of ed. 1.)

				--Blair
				  "!!(But I can't be sure...)"