Re: Is this really necessary

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c++
Subject	Re: Is this really necessary
Date	2021-08-10 06:41 -0700
Organization	A noiseless patient Spider
Message-ID	<86y299zabl.fsf@linuxsc.com> (permalink)
References	(7 earlier) <seo7hm$1b7s$1@gioia.aioe.org> <seolt2$nuj$1@dont-email.me> <seqoel$s5l$1@gioia.aioe.org> <serkdg$jh8$1@dont-email.me> <serkpm$36i$1@gioia.aioe.org>

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MrSpud_HG@_0b772d8ha3yjo0xb.edu writes:

> On Mon, 9 Aug 2021 12:16:46 -0400
> James Kuyper <jameskuyper@alumni.caltech.edu> wrote:
>
>> On 8/9/21 4:19 AM, MrSpud_ifhov@nldls6_1kg3nl2qnwv.biz wrote:

[...]

>>> So long as mathematical operations can be done on the pointer
>>> types (which is a given or they'd be no use as pointers) then
>>> they are de facto integer types and that statement is wrong.
>>
>> Yes, but when these issues come into play, the relevant
>> mathematical operations cannot be done on pointer types.
>> The result of a pointer
>
> They can in *nix which is good enough for me.

A few comments...

One, in many cases C pointers are represented internally as what
are basically integers, but the C standard says pointer types are
distinct from integer types, and the rules for operations on
pointer types, in particular subtraction of pointer values, are
specifed in terms of pointers and arrays and not in terms of
integer values.  The rules for pointer subtraction depend on the
range of the implementation-chosen type ptrdiff_t.

Two, the specific values used for things like ptrdiff_t are
determined by the particular C implementation being used, not the
operating system.  The target OS may influence some choices made
by the implementation, but it is still the implementation's
choice whether to observe those influences.

Three, I can tell you from first-hand experience that problems
related to the range of ptrdiff_t can and do occur in ordinary C
code running on a 32-bit linux system, using gcc to compile.

Thread

Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 12:53 +0200
  Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 14:19 +0200
    Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 14:27 +0200
      Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 14:33 +0200
        Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 15:06 +0200
          Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 15:29 +0200
            Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 17:38 +0200
              Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 17:51 +0200
              Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-05 11:56 -0400
            Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-06-05 19:08 -0400
              Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-06 11:24 +0200
              Re: Is this really necessary Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-06-06 10:33 +0100
                Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 07:56 -0400
                Re: Is this really necessary Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-06-06 15:00 +0100
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 16:20 -0700
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 00:44 -0700
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-07 12:13 -0700
                Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-06-07 21:58 +0200
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 10:25 -0700
                Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-08-07 21:21 +0200
          Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-05 06:34 -0700
          Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-05 20:03 -0400
            Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 12:59 -0700
              Re: Is this really necessary MrSpud_85yGi2@1ahbfz.gov - 2021-08-08 09:18 +0000
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-08 09:23 -0400
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-08 15:04 +0000
                Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-08 13:14 -0400
                Re: Is this really necessary MrSpud_1dgrmf@dx58865qyrdw30lqllb.info - 2021-08-09 08:21 +0000
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-09 08:53 +0000
                Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-09 19:53 +0200
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 05:22 +0000
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 14:54 +0000
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-10 11:41 -0700
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-11 05:39 +0000
                Re: Is this really necessary Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-08-08 20:01 +0100
                Re: Is this really necessary MrSpud_ifhov@nldls6_1kg3nl2qnwv.biz - 2021-08-09 08:19 +0000
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-09 08:55 +0000
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-09 12:16 -0400
                Re: Is this really necessary MrSpud_HG@_0b772d8ha3yjo0xb.edu - 2021-08-09 16:23 +0000
                Re: Is this really necessary Vir Campestris <vir.campestris@invalid.invalid> - 2021-08-09 21:50 +0100
                Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-09 20:57 -0400
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 01:12 +0000
                Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-09 21:21 -0400
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-10 07:13 -0700
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 05:29 +0000
                Re: Is this really necessary MrSpud_12tus_Atff@bya886olr5o8dhu9.ac.uk - 2021-08-10 07:28 +0000
                Re: Is this really necessary Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-08-10 15:34 +0100
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 14:59 +0000
                Re: Is this really necessary MrSpud_wPgnov999o@vv7a6.tv - 2021-08-10 15:54 +0000
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-10 11:29 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 08:45 +0000
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-11 07:05 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 14:18 +0000
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 14:57 +0000
                Re: Is this really necessary MrSpud_pb9bpp7Ej@6urvt16b9fax.gov.uk - 2021-08-10 07:23 +0000
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 15:02 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-10 06:11 -0700
                Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-08-10 16:13 +0200
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-11 12:40 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-12 08:20 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-12 03:50 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-12 14:58 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-12 08:29 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-12 15:39 +0000
                Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-08-12 20:07 +0300
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-13 07:16 +0000
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 09:26 +0000
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-13 10:30 -0400
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 14:58 +0000
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-14 08:07 +0000
                Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-08-14 10:40 -0700
                Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-08-14 10:38 -0700
                Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-13 15:30 +0200
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-13 11:18 -0700
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 03:20 -0700
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-14 13:24 -0700
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-14 20:33 +0000
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-15 00:40 -0400
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-15 07:02 -0700
                Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-15 21:19 +0200
                Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-15 15:42 -0400
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-21 12:38 -0700
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-14 08:13 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 02:58 -0700
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-13 14:32 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 02:28 -0700
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 03:00 -0700
                Re: Is this really necessary Bart <bc@freeuk.com> - 2021-08-14 14:03 +0100
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-14 15:06 +0000
                Re: Is this really necessary "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-08-12 12:06 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 09:19 +0000
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-13 14:35 +0000
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 14:58 +0000
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 15:03 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-11 12:54 -0700
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-11 20:20 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-12 03:42 -0700
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-11 05:45 +0000
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-11 05:26 -0700
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-11 14:06 +0000
                Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-11 14:01 +0000
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-09 23:20 -0400
                Re: Is this really necessary MrSpud_m7k7yilq_8@u6w.biz - 2021-08-10 07:26 +0000
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 07:51 +0000
                Re: Is this really necessary MrSpud_ggBp1lq0@lxz.tv - 2021-08-10 07:59 +0000
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 12:24 +0000
                Re: Is this really necessary MrSpud_u7lm@bxuc3wy1g3cxiqu5j2x1_7iu.com - 2021-08-10 15:51 +0000
                Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-11 05:47 +0000
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 08:46 +0000
                Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-08-10 11:20 +0200
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-10 10:27 -0400
                Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-08-10 17:44 +0200
                Re: Is this really necessary MrSpud_885p_dugji@l6zhsgj_v6t3dbj.tv - 2021-08-10 15:50 +0000
                Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-08-11 08:31 +0200
                Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-10 10:27 -0400
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-10 11:27 -0700
                Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 08:44 +0000
                Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-08-11 16:05 +0300
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-10 06:41 -0700
          Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-06-06 18:48 +0300
            Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 14:26 -0400
            Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 16:10 -0700
              Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 21:30 -0400
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 18:49 -0700
                Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 18:51 -0700
                Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 22:57 -0400
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 09:43 -0700
                Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-07 09:51 -0700
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 10:22 -0700
                Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-06-07 10:13 -0700
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 10:22 -0700
                Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-08-07 12:40 -0700
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 12:54 -0700
              Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-06 23:17 -0700
            Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 09:19 -0700
              Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-06-07 21:58 +0300
                Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-10 11:29 -0700
    Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-05 05:38 -0700
      Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 15:41 +0200
        Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-05 08:18 -0700
          Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-05 11:58 -0400
    Re: Is this really necessary MrSpook_rs7x@4hhtozmpj299zx.tv - 2021-06-05 16:00 +0000
      Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 18:16 +0200
        Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-06 17:34 +0200
        Re: Is this really necessary MrSpook_ie@q67rq6_2ly9ut44j.org - 2021-06-06 13:55 +0000
      Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-06-05 19:50 +0200
        Re: Is this really necessary MrSpook_zn7@4tzq7j92.gov - 2021-06-06 13:59 +0000
    Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-06-05 17:42 -0400
      Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-06 11:05 +0200
      Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 00:27 -0700
  Re: Is this really necessary Vir Campestris <vir.campestris@invalid.invalid> - 2021-06-06 21:27 +0100
    Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-06-07 00:22 +0200
      Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-06-07 14:53 +0000
        Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-07 18:02 +0200
      Re: Is this really necessary Vir Campestris <vir.campestris@invalid.invalid> - 2021-06-16 21:38 +0100
    Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-06-07 14:52 +0000

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