From 7816745175545221861 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,c4044a0e79c89b37,start X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2002-12-18 20:08:25 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.icl.net!newsfeed.fjserv.net!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: georg@nospam.ucar.edu ("Georg D.") Newsgroups: comp.std.c++ Subject: comparing signed and unsigned integral values Date: Thu, 19 Dec 2002 04:08:20 +0000 (UTC) Organization: Customers chello Austria Lines: 41 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: X-Trace: mail2news.demon.co.uk 1040270900 23730 10.0.0.1 (19 Dec 2002 04:08:20 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Thu, 19 Dec 2002 04:08:20 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.05) id 18Oryt-0006AT-00 for mail2news@news.news.demon.net; Thu, 19 Dec 2002 04:08:19 +0000 X-Received: by mulga.cs.mu.OZ.AU id PAA27795; Thu, 19 Dec 2002 15:08:15 +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++@ncar.ucar.edu X-Newsgroups: comp.std.c++ X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4920.2300 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4920.2300 X-NNTP-Posting-Date: Thu, 19 Dec 2002 03:25:15 MET X-Spam-Status: No, hits=2.3 required=5.0 tests=INVALID_MSGID,MEMBER_2,NOSPAM_INC,PRIORITY_NO_NAME, SPAM_PHRASE_00_01 version=2.41 X-Spam-Level: ** Xref: archiver1.google.com comp.std.c++:16196 Hi, The Standard says there are integral conversions (4.7) and what shall happen if the destination is signed or unsigned, but I could not find specification for the destination type of parameters of global comparison operators, e.g. "bool operator < (???, ???)". e.g. "-1 < 2294967295" -> false (32-bit int) with warning: comparing signed and unsigned values. Q1: I'd like to understand which conversions are "performed" prior to comparison. Q2: while comparing signed and unsigned values could have a more acceptable semantics, a C++ compiler will reject bool operator <(int x, unsigned y) { return x < 0 || (unsigned) x < y; } bool operator <(unsigned x, int y) { return y > 0 && x < (unsigned) y; } with " 'operator <(int,unsigned int)' must be a member function or have a parameter of class type" (Standard: 13.5/6) I'd like to read your comments on this and/or get links to existing comments or discussions. TIA, Georg --- [ 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 ]