From 7638292099904207007 X-Google-Thread: f78e5,174aa7b34b06a51 X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.speakeasy.net!news.speakeasy.net.POSTED!not-for-mail NNTP-Posting-Date: Wed, 23 Nov 2005 22:50:05 -0600 Return-Path: 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) Delivered-To: std-c++@ucar.edu From: pongba@gmail.com Newsgroups: comp.std.c++ Subject: Re: Is this really unspecified behavior? Organization: http://groups.google.com Message-ID: <1132786459.216137.307610@z14g2000cwz.googlegroups.com> References: <1132629737.664847.151630@o13g2000cwo.googlegroups.com> <1132722639.345095.296070@f14g2000cwb.googlegroups.com> <200511231401.jANE1BuC092897@horus.isnic.is> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Complaints-To: groups-abuse@google.com User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 2.0.50727),gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: z14g2000cwz.googlegroups.com; posting-host=222.94.28.3; posting-account=t_ay-g0AAADpcfWwZ2b8zZ89gVs9u18v X-Greylisting: NO DELAY (Relay+Sender autoqualified); processed by UCSD_GL-v2.1 on mailbox8.ucsd.edu; Wed, 23 November 2005 14:54:25 -0800 (PST) X-Spamscanner: mailbox8.ucsd.edu (v1.6 Aug 4 2005 15:27:38, -2.6/5.0 3.0.4) X-MailScanner: PASSED (v1.2.8 90804 jANMsOkx002607 mailbox8.ucsd.edu) X-Virus-Scanned: amavisd-new at ucar.edu X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU Approved: Fergus Henderson , moderator of comp.std.c++ X-Virus-Scanned: amavisd-new at cs.mu.OZ.AU Date: Wed, 23 Nov 2005 22:45:31 CST Lines: 27 NNTP-Posting-Host: 65.182.171.162 X-Trace: sv3-etq1p/h5pjRMzm5zdOdxAR6LG2HuPz53FQoarECDVU5XWS2rmMHdD+aiQ6ZpOl+14U9VyDBDqPcjaXz!xmtzvBn9MpCa0UrEsaeLcbehZGW3V/yeo50++Je2CGWibeJVdHksvoGBipWw3OgtmZAly53N53xK!z+RV4LASmk2Z/4c/9cxeB1I9A7r4x/UkafROCbepcyM= X-Complaints-To: abuse@speakeasy.net X-DMCA-Complaints-To: abuse@speakeasy.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Xref: g2news1.google.com comp.std.c++:2584 Hyman Rosen wrote: > No, it's undefined in the built-in case, because i is modified > twice in the same expression (by the increment and by the > assignment) without an intervening sequence point. yeah, that's where my doubt lies exactly. The standard says that "i = v[i++]" has unspecified behavior, but according to what you have said, it should just be undefined behavior. Is there anything wrong with the corresponding standard wording? BTW. If what you said is true, similarly the expression " i = i++"/"i=++i"(whatever) would have undefined behavior,too. It's just that I couldn't believe this little simple expression has undefined behavior, though, I think you were right anyway. Plus, to me it seems very, very confusing to separate the concept of "evaluation" from that of "side-effect", in particular, the evaluation of an expression doesn't necessarily mean that the side-effect of this evaluation takes place simultaneously. Sometimes this behavior is quite puzzling, it's just counterintuitive. --- [ 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 ]