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Groups > comp.lang.c > #15522

Re: Function pointer vs conditional branch

From Michael Angelo Ravera <maravera@prodigy.net>
Newsgroups comp.lang.c
Subject Re: Function pointer vs conditional branch
Date 2012-01-06 23:00 -0800
Organization http://groups.google.com
Message-ID <172590.839.1325919611333.JavaMail.geo-discussion-forums@pril5> (permalink)
References <je2jb2$886$1@speranza.aioe.org>

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On Wednesday, January 4, 2012 2:20:18 PM UTC-8, Edward Rutherford wrote:
> Hello
> 
> As a general rule-of-thumb: Are function pointers more efficient than if 
> statements, if the same path will be taken throughout the course of the 
> program?
> 
> E.g. If I was going to repeatedly render an image in one of three ways, 
> and the method of rendering it gets selected at the beginning of 
> execution: Would it be more efficient to use a function pointer instead 
> of an if statement?

The main improvement may be to readability. It may be cleaner to work out which function to call once and just call it by pointer. The cost of an instruction to make an indirect call to a function or to make a conditional branch will be approximately equal. Either could be more effecient.

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Thread

Function pointer vs conditional branch Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2012-01-04 22:20 +0000
  Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-04 22:46 +0000
  Re: Function pointer vs conditional branch Ian Collins <ian-news@hotmail.com> - 2012-01-05 11:47 +1300
  Re: Function pointer vs conditional branch Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-01-04 20:15 -0500
    Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-05 01:25 +0000
      Re: Function pointer vs conditional branch Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-01-04 20:36 -0500
        Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-05 06:02 +0000
  Re: Function pointer vs conditional branch "BartC" <bc@freeuk.com> - 2012-01-05 01:25 +0000
  Re: Function pointer vs conditional branch Gene <gene.ressler@gmail.com> - 2012-01-04 17:57 -0800
  Re: Function pointer vs conditional branch gordonb.vj0cm@burditt.org (Gordon Burditt) - 2012-01-04 23:54 -0600
  Re: Function pointer vs conditional branch 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-04 23:25 -0800
  Re: Function pointer vs conditional branch 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-04 23:38 -0800
  Re: Function pointer vs conditional branch Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2012-01-05 13:47 -0700
  Re: Function pointer vs conditional branch Nobody <nobody@nowhere.com> - 2012-01-05 21:29 +0000
    Re: Function pointer vs conditional branch Dr Nick <3-nospam@temporary-address.org.uk> - 2012-01-06 06:44 +0000
  Re: Function pointer vs conditional branch BGB <cr88192@hotmail.com> - 2012-01-06 11:41 -0600
    Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-06 18:33 +0000
      Re: Function pointer vs conditional branch Willem <willem@toad.stack.nl> - 2012-01-06 21:41 +0000
        Re: Function pointer vs conditional branch Stephen Sprunk <stephen@sprunk.org> - 2012-01-06 16:08 -0600
        Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-06 22:35 +0000
          Re: Function pointer vs conditional branch BGB <cr88192@hotmail.com> - 2012-01-06 17:00 -0600
            Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-06 23:44 +0000
          Re: Function pointer vs conditional branch Stephen Sprunk <stephen@sprunk.org> - 2012-01-06 17:08 -0600
            Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-06 23:49 +0000
              Re: Function pointer vs conditional branch jacob navia <jacob@spamsink.net> - 2012-01-07 00:55 +0100
                Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-07 00:07 +0000
        Re: Function pointer vs conditional branch "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-01-07 06:14 -0800
          Re: Function pointer vs conditional branch "BartC" <bc@freeuk.com> - 2012-01-07 14:44 +0000
            Re: Function pointer vs conditional branch Robert Wessel <robertwessel2@yahoo.com> - 2012-01-07 14:37 -0600
              Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-07 20:42 +0000
                Re: Function pointer vs conditional branch Stephen Sprunk <stephen@sprunk.org> - 2012-01-07 16:47 -0600
                Re: Function pointer vs conditional branch Robert Wessel <robertwessel2@yahoo.com> - 2012-01-08 01:49 -0600
                Re: Function pointer vs conditional branch Kaz Kylheku <kaz@kylheku.com> - 2012-01-08 08:35 +0000
            Re: Function pointer vs conditional branch Stephen Sprunk <stephen@sprunk.org> - 2012-01-07 17:02 -0600
    Re: Function pointer vs conditional branch "BartC" <bc@freeuk.com> - 2012-01-06 21:29 +0000
      Re: Function pointer vs conditional branch BGB <cr88192@hotmail.com> - 2012-01-06 17:15 -0600
  Re: Function pointer vs conditional branch Michael Angelo Ravera <maravera@prodigy.net> - 2012-01-06 23:00 -0800
  Re: Function pointer vs conditional branch jgk@panix.com (Joe keane) - 2012-01-07 21:04 +0000

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