From -8034781116349428973 X-Google-Thread: f78e5,6978327f896d5d5b X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news1.google.com!news.glorb.com!news-out.ntli.net!newsrout1.ntli.net!news-in.ntli.net!ntli.net!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: francis@robinton.demon.co.uk (Francis Glassborow) Newsgroups: comp.std.c++ Subject: Re: What is the use of the null directive # ? Date: Sun, 27 Jun 2004 22:14:54 +0000 (UTC) Organization: Southfield Microcomputer SS Lines: 49 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: <607f883e.0406251028.5412fc80@posting.google.com> Mime-Version: 1.0 Content-Type: text/plain;charset=us-ascii;format=flowed X-Trace: mail2news.demon.co.uk 1088374494 17827 10.0.0.1 (27 Jun 2004 22:14:54 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Sun, 27 Jun 2004 22:14:54 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.12) id 1BehvJ-0004dO-00 for mail2news@news.news.demon.net; Sun, 27 Jun 2004 22:14:53 +0000 X-Received: from mulga.cs.mu.OZ.AU (localhost [127.0.0.1]) by mulga.cs.mu.OZ.AU with ESMTP id i5RMEnrd015560; Mon, 28 Jun 2004 08:14:49 +1000 (EST) X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i5RMEl6V015543; Mon, 28 Jun 2004 08:14:47 +1000 (EST) X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Path: comp-std-cpp-robomod!not-for-mail X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Delivered-To: std-c++@ucar.edu X-Newsgroups: comp.std.c++ X-User-Agent: Turnpike/6.02-U () X-Spam-Checker-Version: SpamAssassin 2.60-mulga_r1 (1.212-2003-09-23-exp) on mulga.cs.mu.OZ.AU X-Spam-Status: No, hits=-2.8 required=5.2 tests=AWL,BAYES_00, MAILTO_TO_SPAM_ADDR autolearn=no version=2.60-mulga_r1 Xref: g2news1.google.com comp.std.c++:1044 In article , Barry Margolin writes >In article , > francis@robinton.demon.co.uk (Francis Glassborow) wrote: > >> In article <607f883e.0406251028.5412fc80@posting.google.com>, Prateek R >> Karandikar writes >> >What is the use of the null-directive # ? >> > >> > >> > 16.7 Null directive [cpp.null] >> >1 A preprocessing directive of the form >> > # new-line >> > has no effect. >> > >> >> It allows implementors to add directives as extensions without having >> impact on the portability of code using them. > >All it says is that the line: > ># > >is ignored. How does that allow an implementor to add something like: > >#foobar No it does not say that the implementor is _required_ to ignore such a directive. What it does say is that such a directive is not cause to abort compilation, nor does its existence require a diagnostic. It generalises the #pragma directive so that I can write: #packed happy in the knowledge that any compiler that does not understand that directive will simply ignore it. -- Francis Glassborow ACCU Author of 'You Can Do It!' see http://www.spellen.org/youcandoit For project ideas and contributions: http://www.spellen.org/youcandoit/projects --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ]