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| From | 88888 Dihedral <dihedral88888@googlemail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Function pointer vs conditional branch |
| Date | 2012-01-04 23:38 -0800 |
| Organization | http://groups.google.com |
| Message-ID | <1246814.143.1325749134083.JavaMail.geo-discussion-forums@prar8> (permalink) |
| References | <je2jb2$886$1@speranza.aioe.org> |
Edward Rutherford於 2012年1月5日星期四UTC+8上午6時20分18秒寫道：
> 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?
>
> Thanks.
I'll give an example in pseudo code here for problems in your post.
How to turn a gray level image into a binary one?
The rule: given a Th=170, if the gray level>=Th just make it 255 else 0
//Method1:
for each pixel:
if gray>=Th store 255; else store 0;
//Method2:
for(i=0;i<Th;i++) map[i]=0;
for(; i<256;i++) map[i]=255;
for each pixel in the image:
store map[gay];
Both methods will work.
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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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