From -174230353307037907 X-Google-Thread: f78e5,27c2a088314ec0a9 X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!proxad.net!news2.telebyte.nl!border2.nntp.ams.giganews.com!border1.nntp.ams.giganews.com!nntp.giganews.com!news-hub.cableinet.net!blueyonder!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!stump.algebra.com!devnull From: dhruvbird@gmx.net ("Dhruv Matani") Newsgroups: comp.std.c++ Subject: Re: should std::vector<> exponential growth rate be followed strictly in times of low availabe memory. Date: Wed, 27 Oct 2004 03:43:46 GMT Lines: 48 Sender: mail2news@demon.net Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: <417E434E.5000209@bubblescope.net> NNTP-Posting-Host: news.news.demon.net Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: news.demon.co.uk 1098848634 23249 158.152.254.254 (27 Oct 2004 03:43:54 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Wed, 27 Oct 2004 03:43:54 +0000 (UTC) X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-User-Agent: Pan/0.13.3 (That cat's something I can't explain) X-Orig-X-Trace: news.uni-berlin.de h6rYHu87gZCTxYt7Mr1qtA8d9Yld9EJUg91oTjTpSESEwqDEgc X-Virus-Scanned: by amavisd-new at cs.mu.OZ.AU X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i9R3hlrt002899; Wed, 27 Oct 2004 13:43:47 +1000 (EST) X-Path: comp-std-cpp-robomod!not-for-mail X-Delivered-To: std-c++@ucar.edu X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Newsgroups: comp.std.c++ Xref: g2news1.google.com comp.std.c++:3200 On Tue, 26 Oct 2004 21:18:18 +0000, chris wrote: > Dhruv Matani wrote: >> Hello, >> I recently had a discussion about whether the exponential growth policy >> for std::vector<> should be followed strictly no matter what. >> >> The case I'm looking at is something like this: >> >> const int init_sz = 1.2 * 1024 * 1024 * 1024; // 1.2GB. >> std::vector cv(init_sz); >> cv.push_back('a'); >> > .. >> Assume that the growth factor is 2. > .. >> What my argument is that an implementations should be allowed to deviate >> slightly from the standard to prevent useless exception like the above >> from being thrown. It should be clear that from the user's point of view, >> what he sees is that he already has 1.2GB of data, and he is trying to add >> 1-byte to that! Why for any reason should that fail? Assume that the user >> is in no position to use reserve. Obviously if that is considered, then >> the whole post is useless ;-) > If your only aim is to remain standards compliant, then one option would > be to reduce what you claim the minimum growth factor will be in tight > memory situations, say to 1.05. If you can't extend the vector by at > least 5% then is it really worth doing it? In this way you could perform > better in low memory situations but still be standard compliant. > > If you wanted to be really sick, you could claim that your minimum > growth factor is 1+5*10^(-20), which would mean that on a system with a > 64-bit address space you would still never have to expand by more than > 1, but I believe you could still claim to be standards compliant ;) Yes, but it would obviously be a nonsense implementation as you have mentioned. I'm looking more at making it allowable by the standard in such low memory situations to deviate from the exponential growth policy. Reagrds, -Dhruv. --- [ 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 ]