From -3461568519221968421 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,924f354765fe932a X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2002-05-18 12:35:02 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news.uchicago.edu!yellow.newsread.com!netaxs.com!newsread.com!newsfeed00.sul.t-online.de!t-online.de!kibo.news.demon.net!news.demon.co.uk!demon!mail2news.demon.co.uk!not-for-mail From: Gabriel Dos Reis Newsgroups: comp.std.c++ Subject: Re: constructor calls in vectors Date: Sat, 18 May 2002 19:34:53 GMT Organization: CodeSourcery, LLC Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: References: <3CE562E8.8050403@acm.org> X-Trace: mail2news.demon.co.uk 1021750497 mail2news:21195 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) Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII NNTP-Posting-Date: Fri, 17 May 2002 23:28:44 +0000 (UTC) X-Newsreader: Gnus v5.7/Emacs 20.7 Lines: 66 Xref: archiver1.google.com comp.std.c++:11358 James Dennett writes: | Francis Glassborow wrote: | > In article , Eric J. Korpela | > writes | > | >> Quick (or maybe not so quick) std::vector question. Does the | >> standard specify what constructors will be called during creation | >> of a vector? For example when I have classes like the following... | >> | >> class A { | >> public: | >> int i; | >> A(); // Constructor: Details left to the imagination | >> A(const A &a); // Copy Constuctor: Ditto | >> }; | >> | >> int main(void) { | >> std::vector B(1024)); | >> } | >> | >> My problem is in porting some code between two platforms. On one | >> platform | >> the A() constructor is called for every element. | > | > | > see 23.2.4.1. where the signature of the relevant ctor for vector | > strongly implies that the copy ctor is expected to be used to initialise | > the elements of a vector. I do not see anything that forbids the | > alternative. | | The fact that the behaviour is specified; there's a single constructor ^^^^^^ | which takes a size_type argument and a defaulted const reference to | ElementType (followed by a defaulted allocator argument which I'm | largely ignoring here), Actually, the standard is a little more permissive than that: 17.4.4.4/2: An implementation can declare additional non-virtual member function signatures within a class: --- by adding arguments with default values to a member function signature;172) The same latitude does not extend to the implementation of virtual or global functions, however. --- by replacing a member function signature with default values by two or more member function signatures with *equivalent behavior*; --- by adding a member function signature for a member function name. (Emphasis is mine) | and it is specified as filling the vector | with copies of the second argument by Table 67 (from sequence | container requirements). Agreed, by a literal reading of the standard. -- Gabriel Dos Reis, dosreis@cmla.ens-cachan.fr --- [ 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 ]