From 6349321320574440824 X-Google-Thread: f78e5,174aa7b34b06a51,start X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.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: Mon, 21 Nov 2005 23:30:32 -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: Is this really unspecified behavior? Organization: http://groups.google.com Message-ID: <1132629737.664847.151630@o13g2000cwo.googlegroups.com> 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: o13g2000cwo.googlegroups.com; posting-host=222.94.28.3; posting-account=t_ay-g0AAADpcfWwZ2b8zZ89gVs9u18v 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: Mon, 21 Nov 2005 23:20:16 CST Lines: 48 NNTP-Posting-Host: 65.182.171.162 X-Trace: sv3-7PyTMtyXtblJOPR5D8vEFBEDFNet4aIcHaepA4L3DkM1itprW1T5ThS2jvHKytNBYqnG/bNTFlAT2un!0dLtuv7dgykWJAd4DS8ovN63l9KO0mkGVZkfD07JiR+xdm8Arm40Pm/1g2AlZNLEo/2brJ8f6vdC!tWXnnCbH271otHDT54gCnEkSOghZrKZ7ejIRAO+GhMg= 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++:2574 C++03 5/4: [Example: i = v[i++]; // the behavior is unspecified . ] I wanna ask that if v is a std::vector which overloads operator[], is this unspecified any more? What I understand is that there's a sequence point at the entry and exit of a function call, well, operator function certainly is a function, so if we change that 'v' to a object of std::vector, v[i++] becomes a function call, the side effect of which takes place before the assignment operation, therefore 'i' gets a determinable value, which is v[*old value of the i*], which of course is not unspecified. That said, I wonder if this analysis is right, did I miss or misunderstand anything? If that is true, is this an evidence that some inconsistency, in some extremely non-obvious way, exists between build-in operator and operator function(informally known as 'overloaded operator'). Another question is: What is the side-effect of 'i++' actually? Two options, first of which is "fetch i from memory, add it by 1, write the new value back", second is "write the new value stored previously somewhere into the storage of 'i'". Is the answer 'both' or 'either' or whatever? Plus, the words below(also excerpted from [c++03;5/4])are really puzzling to me, can anyone explain it please? Does it have anything to do with the two questions I asked? [C++03;5/4]"Between the previous and next sequence point a scalar object shall have its stored value modified at most once by the evaluation of an expression. Furthermore, the prior value shall be accessed only to determine the value to be stored.The requirements of this paragraph shall be met for each allowable ordering of the subexpressions of a full expression; otherwise the behavior is undefined." Any help is appreciated;-) --- [ 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 ]