From -5571625749113199451 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,d93488bb970aa444 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2001-06-20 10:23:38 PST From: MikeAlpha@NoSpam_csi.com (Martin Aupperle) Newsgroups: comp.std.c++ Subject: Re: How to test for NaNs and infinites? Date: Wed, 20 Jun 2001 17:14:37 GMT Organization: Nikoma Mediaworks GmbH Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <3b3097a6.200675926@news.nikoma.de> References: <3B176D2F.70C3E7F7@meteo.fr> <9fql8h$pfg$1@news.hal-pc.org> <3B21100E.5B25F7AA@acm.org> <9frdlp$14bc$1@news.hal-pc.org> <9g2em7$1pkk$1@news.hal-pc.org> <9g7q93$1lu1$1@news.hal-pc.org> <3B278187.9E196C80@acm.org> X-Trace: mail2news.demon.co.uk 993057285 mail2news:22314 mail2news mail2news.demon.co.uk X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) NNTP-Posting-Date: Wed, 20 Jun 2001 14:27:49 +0000 (UTC) X-Newsreader: Forte Free Agent 1.21/32.243 Lines: 49 Path: archiver1.google.com!newsfeed.google.com!sn-xit-03!supernews.com!freenix!feed.ac-versailles.fr!proxad.net!fr.clara.net!heighliner.fr.clara.net!diablo.netcom.net.uk!netcom.net.uk!dispose.news.demon.net!news.demon.co.uk!demon!mail2news.demon.co.uk!not-for-mail Xref: archiver1.google.com comp.std.c++:6217 On Wed, 13 Jun 2001 15:19:20 GMT, Pete Becker wrote: >>From the C++ language definition: > > 1.3.12 undefined behavior > > behavior, such as might arise upon use of an erroneous program >construct > or erroneous data, for which this International Standard imposes no > requirements. ... [Note: permissible undefined behavior ranges from > ignoring the situation completely with unpredictable results, to >behaving > during translation or program execution in a documented manner >characteristic > of the environment (with or without the issuance of a diagnostic >message), to > terminating a translation or execution (with the issuance of a >diagnostic > message). > >Of course, the Standard can't say that something is "illegal"; all it >can say is that it cannot be used in a conforming program. And that's >precisely what the above definition says. Code that produces undefined >behavior does not conform to the language definition. Or, in the usual >colloquialism, it's illegal. > In some of my earlier projects it was not uncommon to make direkt screen output by writing ints into some memory locations. The ints had a char that was the character and another that ws the attribute (color, etc. ) Of course we used unions. Sounds familiar? Im am disappointed to learn that those programs were all illegal, and not valid C++. Martin ------------------------------------------------ Martin Aupperle MikeAlpha@NoSpam_csi.com (remove NoSpam_) ------------------------------------------------ --- [ 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.research.att.com/~austern/csc/faq.html ]