Path: utzoo!attcan!uunet!husc6!bbn!gatech!dcatla!holos0!lbr
From: lbr@holos0.UUCP (Len Reed)
Newsgroups: comp.lang.c
Subject: Re: defining a comment?
Message-ID: <1356@holos0.UUCP>
Date: 15 Sep 88 13:33:21 GMT
References: <13544@mimsy.UUCP>
Organization: Holos Software, Atlanta, GA
Lines: 44

From article <13544@mimsy.UUCP>, by chris@mimsy.UUCP (Chris Torek):
> In article <5438@techunix.BITNET> benny@techunix.BITNET (Benny Pinkas) writes:
>>Can I use the Preprocessor to define a comment?
> 
>>#define STARTCOM /*
> 
> This is rather dubious.
> 
>>Usually the text after the /* is considered as a comment and is not part
>>of the macro definition.
> 
> Why should you care?  You cannot (portably) view the text (if any) emitted
> by the preprocessor, which may well be an integral part of the compiler.

You misunderstand.  On Xenix and MSC 5.x (where I've tried this) consider:

#define COMMENT /*
#define CLOSE_COMMENT */

The pre-processor considers these two lines to be functionally equivalent
to the single line:

#define COMMENT /* #define CLOSE_COMMENT */

which is no different than

#define COMMENT

This is because comment structures are parsed in the 1st pass before #defines.
Comments are not stored in the pre-processor lookup table.
Later when you say:

COMMENT
	A whole bunch of stuff
CLOSE_COMMENT

the compiler tries to compile

	A whole bunch of stuff
CLOSE_COMMENT

and messes up.
-- 
    -    Len Reed