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Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle...

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Keith Thompson <kst-u@mib.org> wrote:
> Malcolm McLean <malcolm.mclean5@btinternet.com> writes:

(snip)
>> Indexing is a very common operation. So if you have a machine that
>> supports 64 bit types, but can process 32 bit types twice as fast
>> (maybe because what limits it is cache size), and virtually no
>> indexing operation goes above 2 billion, then you can gain a 2x
>> speed up by making all your index variables 32 bit.

>> Probably a bad idea, but tempting.

There are plenty of problems where the maximum size is known.
It is unlikely that years will ever have more than 32767 days...
 
> Sure, an implementation for such a machine can make size_t 32 bits
> and refuse to support objects bigger than 2**32 bytes.  And code
> that uses size_t for indexing automatically gets the performance
> gains of that decision.

I have seen installers not install something when the available
disk or RAM was greater than 2GB, complaining that not enough
(something) was available.

Someday soon, I want to see what SunOS 4.x does with an NFS server
and a 3TB disk. (I suspect they didn't think about that at the time.)
 
> If an implementation supports objects bigger than 2**32 bytes,
> but your program never creates such large objects, and if
> using 32-bit indices rather than 64-bit size_t results in a
> substantial performance improvement, then that could be a reasonable
> application-level optimization -- but you risk a loss of portability
> and/or extensibility.

-- glen

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Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... G G <gdotone@gmail.com> - 2015-05-07 17:12 -0700
  Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-07 18:18 -0700
    Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... G G <gdotone@gmail.com> - 2015-05-07 20:16 -0700
      Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... mark.bluemel@gmail.com - 2015-05-08 01:09 -0700
      Re: Could you please discuss whether casting a size_t variable to   unsigned int variable is the correct way to handle... Tim Prince <tprince@computer.org> - 2015-05-08 09:16 -0400
      Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-08 08:03 -0700
        Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-05-08 10:30 -0700
          Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... jadill33@gmail.com - 2015-05-08 11:12 -0700
          Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-08 11:22 -0700
            Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-08 18:42 +0000
          Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Bartc <bc@freeuk.com> - 2015-05-08 19:25 +0100
            Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Stephen Sprunk <stephen@sprunk.org> - 2015-05-08 15:12 -0500
              Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Bartc <bc@freeuk.com> - 2015-05-08 22:38 +0100
                Re: Could you please discuss whether casting a size_t variable to   unsigned int variable is the correct way to handle... Ian Collins <ian-news@hotmail.com> - 2015-05-09 11:01 +1200
        Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-10 09:19 -0700
          Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-10 11:26 -0700
            Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-11 21:31 -0700
              Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-12 05:50 +0000
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-12 10:05 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-12 11:10 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-12 12:59 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-22 08:11 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-22 11:20 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-24 07:59 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-24 13:44 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-12 11:09 -0700
              Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-05-12 11:02 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-22 08:01 -0700
            Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Waldek Hebisch <hebisch@antispam.uni.wroc.pl> - 2015-06-08 01:06 +0000
              Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-07 19:12 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... James Kuyper <jameskuyper@verizon.net> - 2015-06-08 11:28 -0400
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Waldek Hebisch <hebisch@antispam.uni.wroc.pl> - 2015-06-09 12:23 +0000
            Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-06-08 10:56 -0700
              Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-08 11:32 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Bartc <bc@freeuk.com> - 2015-06-08 19:40 +0100
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Richard Heathfield <rjh@cpax.org.uk> - 2015-06-08 20:03 +0100
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-08 13:43 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-06-08 21:03 +0000
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-08 14:52 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-06-09 08:30 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-09 16:48 +0100
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-09 08:55 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-06-10 10:09 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-10 11:05 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-06-11 11:04 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-06-11 11:31 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-06-11 13:49 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-06-12 09:00 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 07:25 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-07-11 10:04 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... James Kuyper <jameskuyper@verizon.net> - 2015-07-11 13:39 -0400
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 13:44 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Keith Thompson <kst-u@mib.org> - 2015-07-11 16:15 -0700
                Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... David Kleinecke <dkleinecke@gmail.com> - 2015-06-09 08:31 -0700
  Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-05-07 20:34 -0700
    Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... Richard Heathfield <rjh@cpax.org.uk> - 2015-05-08 09:48 +0100
  Re: Could you please discuss whether casting a size_t variable to unsigned int variable is the correct way to handle... glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-08 05:12 +0000

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