From 5779229166741391559 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,8372ae6de42be399 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2004-02-20 14:25:17 PST Path: archiver1.google.com!news1.google.com!sn-xit-02!sn-xit-01!sn-xit-08!supernews.com!newsfeed.news2me.com!newsfeed.icl.net!newsfeed.fjserv.net!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: do-not-spam-benh@bwsint.com (Ben Hutchings) Newsgroups: comp.std.c++ Subject: Re: Array of size 0 Date: Fri, 20 Feb 2004 22:25:16 +0000 (UTC) Lines: 34 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: <403601F6.8010706@ircad.u-strasbg.fr> X-Trace: mail2news.demon.co.uk 1077315916 28000 10.0.0.1 (20 Feb 2004 22:25:16 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Fri, 20 Feb 2004 22:25:16 +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 1AuJ59-0007HT-00 for mail2news@news.news.demon.net; Fri, 20 Feb 2004 22:25:15 +0000 X-Received: from mulga.cs.mu.OZ.AU (localhost [127.0.0.1]) by mulga.cs.mu.OZ.AU with ESMTP id i1KMPCi2016950; Sat, 21 Feb 2004 09:25:12 +1100 (EST) X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i1KMPBXP016941; Sat, 21 Feb 2004 09:25:11 +1100 (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-Reply-To: Ben Hutchings X-Orig-NNTP-Posting-Host: cpc1-cmbg1-4-0-cust94.cmbg.cable.ntl.com (62.253.133.94) X-Orig-X-Trace: news.uni-berlin.de 1077304505 47792262 I 62.253.133.94 ([70929]) X-Orig-Path: decadentplace.org.uk!nobody X-User-Agent: slrn/0.9.7.4 (Linux) X-Spam-Level: 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=0.0 required=5.2 tests=none autolearn=no version=2.60-mulga_r1 Xref: archiver1.google.com comp.std.c++:1187 Julien Lamy wrote: > Hello, > According to paragraph 6 of item 5.3.4 in the Standard, it is legal to > dynamically allocate an array of size 0, i.e. > new int[0] > is legal. > However, as I understand paragraph 1 of item 8.3.4 ("if the cosntant > expression is present, [...] its value shall be greater than zero"), it > is not legal to have > int myArray[0] > What is the rationale behind this difference ? I don't know what reasons the committee had, and sadly they were not systematically recorded, but I can certainly see a justification. If the program does not decide until run-time just how many elements will be in an array (as in the case of a new-expression) then it is reasonable that it might sometimes decide that there will be none at all, and the programmer shouldn't need to make that a special case. However, if the programmer must decide in advance how many elements there will be (as in the case of a declaration) then clearly there is no point in creating an array that will always be empty. (Some implementations allow declaration of arrays of dimension 0 as an extension, but the main reason for this is to support another extension which allows an array at the end of a struct to be treated as having a larger dimension than it is declared with.) --- [ 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 ]