From -4012858817936338799 X-Google-Language: ENGLISH,ASCII X-Google-Thread: f78e5,5be30c38f618a07b X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2002-05-06 07:52:01 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!kibo.news.demon.net!news.demon.co.uk!demon!mail2news.demon.co.uk!not-for-mail From: James Kanze Newsgroups: comp.std.c++ Subject: Re: Why switch w/ only integral types? Date: Mon, 6 May 2002 14:51:17 GMT Organization: James Kanze Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <86d6w9a76w.fsf@alex.gabi-soft.de> References: <6ee7d287.0203202005.63e0b7b3@posting.google.com> <3CCE6310.672E55DF@webmaster.com> X-Trace: mail2news.demon.co.uk 1020696682 mail2news:1567 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) User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 X-MIME-Autoconverted: from 8bit to quoted-printable by mailbox2.ucsd.edu id g46ASDF5021935 X-MIME-Autoconverted: from quoted-printable to 8bit by mulga.cs.mu.OZ.AU id UAA23732 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by mulga.cs.mu.OZ.AU id AAA10979 Lines: 37 Xref: archiver1.google.com comp.std.c++:11063 "Pavel Kuznetsov" writes: |> David Schwartz (davids@webmaster.com) wrote: |> DS> and on many platforms is actually slower than corresponding |> DS> if/else code at low levels of optimization. |> At least on one platform code generated from switch/case is a lot |> faster than that from if/else if.=20 More generally, I would say that the code generated for switch/case should never be slower than that for if/else if. Because generating a series of if/else if is a perfectly legitimate way of implementing switch/case, and if it is the fastest way, the compiler should choose it. In practice, I cannot conceive of an architecture on which switch/case would not be faster for at least some cases of switches. |> And of course speed is not right factor for choosing between |> if/else and case. Readability and ease of maintainance is. Unless, of course, profiling has shown that there is a problem, and that the problem is due to the implementation of switch. --=20 James Kanze mailto:kanze@gabi-soft.de Conseils en informatique orient=E9e objet/ Beratung in objektorientierter Datenverarbeitung Ziegelh=FCttenweg 17a, 60598 Frankfurt, Germany Tel. +49(0)179 2607481 --- [ 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 ]