Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
| From | James Kuyper <jameskuyper@verizon.net> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Performance of signed vs unsigned types |
| Date | 2011-04-20 09:49 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <iomoa5$vfr$1@dont-email.me> (permalink) |
| References | <alpine.LFD.2.02.1104201414030.21950@bowman> |
On 04/20/2011 09:21 AM, Thomas Scrace wrote:
> Hi all,
>
> In K&R there is an exercise to compute the range of possible values for each C
> type. In doing this I have written two functions that are identical, except for
> the fact that one uses signed long ints, and the other uses unsigned long ints.
> I have found that the function that uses the unsigned ints completes in a few seconds,
> while the signed version takes so long that I have never had the patience to
> wait for it to end. The only operators I am using on the variables are increment
> and decrement.
>
> Is there a difference in performance between these types? Is this restricted to
> long ints, or is there a general difference between all signed/non-signed C
> types? Could this be something compiler or processor specific? I am using GCC on
> the x86 platform (intel core i5).
The most important differences between unsigned and signed types are not
in their performance, but their behavior.
I'm not familiar with the exercise you're referring to, I only have a
copy of the first edition of K&R, which might not even have that
exercise (I didn't find it in a quick glance through the book).
The easiest way to determine the limits of the C types is to use the
macros from <limits.h>, but I presume that would defeat the point of the
exercise. There as safe and quite trivial methods of computing the range
of an unsigned type, but most of the ways I can think of for computing
the range of a signed type are subject to serious portability issues.
What do you expect the following function to do?
#include <limits.h>
long next_after_last(void)
{
return LONG_MAX + 1L;
}
Your answer to that question is likely to be closely related to the
reason your program is stuck.
--
James Kuyper
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 14:21 +0100
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-20 09:49 -0400
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 15:21 +0100
Re: Performance of signed vs unsigned types Peter Nilsson <airia@acay.com.au> - 2011-04-20 15:34 -0700
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-21 17:57 +0100
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-21 19:26 +0100
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-20 21:45 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-21 06:20 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-21 13:54 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-21 18:50 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-21 16:16 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-21 19:27 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-21 17:24 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-21 21:00 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-21 21:33 -0700
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-22 08:22 +0100
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-22 14:25 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-22 09:21 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-22 14:22 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-22 17:58 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-22 17:33 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-23 09:01 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-23 14:07 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-23 18:14 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 11:42 -0700
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-25 22:34 -0400
Re: Performance of signed vs unsigned types gordonb.nw63u@burditt.org (Gordon Burditt) - 2011-04-26 10:59 -0500
Re: Performance of signed vs unsigned types "madamemandm@yahoo.com" <madamemandm@yahoo.com> - 2011-04-22 07:55 -0700
Re: Performance of signed vs unsigned types Noob <root@127.0.0.1> - 2011-04-22 17:03 +0200
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-22 08:42 -0700
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-22 14:15 -0700
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-22 15:23 -0700
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-22 17:37 -0700
Re: Performance of signed vs unsigned types Seebs <usenet-nospam@seebs.net> - 2011-04-23 02:46 +0000
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-23 14:04 -0700
Re: Performance of signed vs unsigned types Barry Schwarz <schwarzb@dqel.com> - 2011-04-23 14:28 -0700
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 11:43 -0700
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-23 23:38 +0100
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 11:46 -0700
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-25 22:43 +0100
Re: Performance of signed vs unsigned types Seebs <usenet-nospam@seebs.net> - 2011-04-24 11:34 +0000
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 11:47 -0700
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-25 12:32 -0700
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 20:25 -0700
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-26 07:45 -0700
Re: Performance of signed vs unsigned types lawrence.jones@siemens.com - 2011-04-24 23:50 -0400
Re: Performance of signed vs unsigned types Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-04-25 02:13 -0700
Re: Performance of signed vs unsigned types Ian Collins <ian-news@hotmail.com> - 2011-04-25 21:36 +1200
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 11:48 -0700
Re: Performance of signed vs unsigned types lawrence.jones@siemens.com - 2011-04-25 16:32 -0400
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-25 15:22 -0700
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 20:32 -0700
Re: Performance of signed vs unsigned types "io_x" <a@b.c.invalid> - 2011-04-26 09:42 +0200
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-26 12:04 +0100
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-26 08:15 -0700
Re: Performance of signed vs unsigned types Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-04-26 08:35 -0700
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-26 08:52 -0700
Re: Performance of signed vs unsigned types Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-04-26 09:15 -0700
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-26 10:22 -0700
Re: Performance of signed vs unsigned types gordonb.s68qo@burditt.org (Gordon Burditt) - 2011-04-26 19:59 -0500
Re: Performance of signed vs unsigned types "madamemandm@yahoo.com" <madamemandm@yahoo.com> - 2011-04-27 14:15 -0700
Re: Performance of signed vs unsigned types "io_x" <a@b.c.invalid> - 2011-04-28 12:15 +0200
Re: Performance of signed vs unsigned types Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-04-28 03:26 -0700
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-28 12:09 +0100
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-28 08:03 -0400
Re: Performance of signed vs unsigned types Seebs <usenet-nospam@seebs.net> - 2011-04-28 16:44 +0000
Re: Performance of signed vs unsigned types Gordon Burditt <gordon@hammy.burditt.org> - 2011-04-29 05:42 -0500
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 20:27 -0700
Re: Performance of signed vs unsigned types Ian Collins <ian-news@hotmail.com> - 2011-04-26 15:30 +1200
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-26 00:14 -0700
Re: Performance of signed vs unsigned types Ian Collins <ian-news@hotmail.com> - 2011-04-26 20:23 +1200
Re: Performance of signed vs unsigned types Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-04-26 04:17 -0700
Re: Performance of signed vs unsigned types Ike Naar <ike@sverige.freeshell.org> - 2011-04-22 06:46 +0000
Re: Performance of signed vs unsigned types James Kuyper <jameskuyper@verizon.net> - 2011-04-22 09:37 -0400
Re: Performance of signed vs unsigned types Michael Press <rubrum@pacbell.net> - 2011-04-25 11:49 -0700
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-22 09:09 -0700
Re: Performance of signed vs unsigned types "madamemandm@yahoo.com" <madamemandm@yahoo.com> - 2011-04-22 09:46 -0700
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-22 20:21 +0100
Re: Performance of signed vs unsigned types "Scott Fluhrer" <sfluhrer@ix.netcom.com> - 2011-04-20 10:06 -0400
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 15:28 +0100
Re: Performance of signed vs unsigned types Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-04-20 16:11 +0100
Re: Performance of signed vs unsigned types Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-04-20 08:14 -0700
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 16:24 +0100
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 17:09 +0100
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 17:19 +0100
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-20 12:09 -0700
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 21:39 +0100
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-20 15:01 -0700
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-21 11:16 +0100
Re: Performance of signed vs unsigned types "Scott Fluhrer" <sfluhrer@ix.netcom.com> - 2011-04-20 13:06 -0400
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-20 18:16 +0100
Re: Performance of signed vs unsigned types gordonb.bfd7y@burditt.org (Gordon Burditt) - 2011-04-21 11:22 -0500
Re: Performance of signed vs unsigned types Thomas Scrace <tom@scrace.org> - 2011-04-21 19:27 +0100
Re: Performance of signed vs unsigned types Keith Thompson <kst-u@mib.org> - 2011-04-21 12:09 -0700
csiph-web