Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!uwm.edu!cs.utexas.edu!uunet!microsoft!jimad
From: jimad@microsoft.UUCP (Jim ADCOCK)
Newsgroups: comp.lang.c++
Subject: Re: cpp and _main()
Keywords: cpp, initialization, macro replacement
Message-ID: <59854@microsoft.UUCP>
Date: 14 Dec 90 19:53:18 GMT
References: <1204@halley.UUCP>
Reply-To: jimad@microsoft.UUCP (Jim ADCOCK)
Organization: Microsoft Corp., Redmond WA
Lines: 34

In article <1204@halley.UUCP> kelley@halley.UUCP (Michael Kelley) writes:
|
|I've got a couple more questions.  The first concerns pre-processing:
|is the text replacement for a macro containing a C++ style comment defined?

Yes, see ARM's chapter on pre-processor.

[and/]
|or will it vary from cpp to cpp?  

Yes, because today's implementations of cpp's are not very good at following
the C++ definition.  There are at least four major flavors of cpp's in 
use today.  Those following K&R, those following ANSI-C, those following
ARM, and those doing entirely their own thing.  If one wants to port
software easily today then, one would do best not to rely on fine-grained 
details of the cpp implemention.

|That is, if I have an ostream for debugging,
|named cdbg, can I do this to take out the code when not debugging:
|
|#ifndef DEBUG
|extern ostream cdbg;
|#else
|#define cdbg //
|#endif

As I understand it, in theory each comment should be converted to a single
white space at a pre-processing phase prior to macro evaluation and 
expansion.  So your cdbg line is equivalent to:

#define cdbg 

In practice, many cpps still do not recognize // as a comment, so the
behavior you get will probably vary.