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Groups > comp.lang.c > #103165
| From | Tim Rentsch <txr@alumni.caltech.edu> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: language changes to optimize for speed in qsort? |
| Date | 2017-02-04 11:28 -0800 |
| Organization | A noiseless patient Spider |
| Message-ID | <kfnwpd57o3f.fsf@x-alumni2.alumni.caltech.edu> (permalink) |
| References | <o72ij4$448$1@dont-email.me> <fff9dc25-f8dd-4872-95f3-6808f5c4f959@googlegroups.com> |
supercat@casperkitty.com writes: > On Friday, February 3, 2017 at 12:38:11 PM UTC-6, mathog wrote: >> ANSI C provides the qsort() function which is very general and >> convenient. Unfortunately the generality part comes from passing in a >> comparison function, and for large sorts it is often factors of 2 or 3 >> slower than one's own quicksort with the comparison operations coded >> directly in the function (so that no comparison function is passed or >> called). It would be nice to have the speed of the specifically coded >> qsorts - without having to code them specifically. > > In addition to having to use a comparison function, qsort() > also suffers from the need to perform all swaps using something > equivalent to memmove() or memcpy() even if the things being > sorted are pointers. [...] Not so. qsort() is part of the standard library, and as such it can take advantage of information known to the implementation but not available to regular C programs.
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language changes to optimize for speed in qsort? mathog <dmathog@gmail.com> - 2017-02-03 10:36 -0800
Re: language changes to optimize for speed in qsort? Robert Wessel <robertwessel2@yahoo.com> - 2017-02-03 17:15 -0600
Re: language changes to optimize for speed in qsort? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-03 16:26 -0800
Re: language changes to optimize for speed in qsort? Robert Wessel <robertwessel2@yahoo.com> - 2017-02-05 02:58 -0600
Re: language changes to optimize for speed in qsort? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-05 03:01 -0800
Re: language changes to optimize for speed in qsort? Gareth Owen <gwowen@gmail.com> - 2017-02-05 13:03 +0000
Re: language changes to optimize for speed in qsort? Robert Wessel <robertwessel2@yahoo.com> - 2017-02-06 04:30 -0600
Re: language changes to optimize for speed in qsort? supercat@casperkitty.com - 2017-02-05 10:07 -0800
Re: language changes to optimize for speed in qsort? supercat@casperkitty.com - 2017-02-03 16:42 -0800
Re: language changes to optimize for speed in qsort? Ian Collins <ian-news@hotmail.com> - 2017-02-04 13:46 +1300
Re: language changes to optimize for speed in qsort? supercat@casperkitty.com - 2017-02-03 16:57 -0800
Re: language changes to optimize for speed in qsort? Keith Thompson <kst-u@mib.org> - 2017-02-03 18:39 -0800
Re: language changes to optimize for speed in qsort? Tim Rentsch <txr@alumni.caltech.edu> - 2017-02-04 11:28 -0800
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