Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!nrl-cmf!mailrus!tut.cis.ohio-state.edu!osu-cis!n8emr!oink!jep
From: jep@oink.UUCP (James E. Prior)
Newsgroups: comp.lang.c
Subject: Re: C Style (Was Re: == vs =)
Message-ID: <255@oink.UUCP>
Date: 21 Apr 88 03:32:25 GMT
References: <11216@brl-adm.ARPA> <2111@chinet.UUCP> <4403@garfield.UUCP> <226@hotlr.ATT> <130@obie.UUCP> <5981@utcsri.UUCP> <1982@ubc-cs.UUCP> <126@atpal.UUCP> <2823@mmintl.UUCP>
Reply-To: jep@oink.UUCP (James E. Prior)
Organization: Random Prime Research Institute  Columbus, Ohio
Lines: 28

In article <2823@mmintl.UUCP> franka@mmintl.UUCP (Frank Adams) writes:
>In article <126@atpal.UUCP> tneff@atpal.UUCP (Tom Neff) writes:
>>If you get into the habit of never writing if(variable),
>>you don't tend to have =/== accidents, in my experience.
>
>I wouldn't say "never write if(variable)"; rather "only write if(variable)
>if variable is Boolean".  In my opinion, things like if(variable==TRUE) are
>abominations.

Amen!, and I'll go one further

   if (var==TRUE)

is not only abominable, it can be dangerous.  var==TRUE tends to presume
that the only valid values of var are FALSE and TRUE.  There are times
when a var can very intentionally have a non-zero (true) value other than
TRUE (1).  The classic kind of case of this is var=isalpha(c).  The
isxxxxx(c) functions are often defined as macros like:

   #define isxxxxxx(c)  (attribute_array[c] & MASK_XXXX)

Each element of the array consists of a bunch of bit attributes.  The
MASK_XXXX selects the attributes of interest, often yeilding true but
non-one (non-TRUE) values.

-- 
Jim Prior    {ihnp4|osu-cis}!n8emr!oink!jep    jep@oink.UUCP

Pointers are my friend.