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Re: My dynamic arrays module [was:Re: Pointer conversion and alignment]

From James Kuyper <jameskuyper@alumni.caltech.edu>
Newsgroups comp.lang.c
Subject Re: My dynamic arrays module [was:Re: Pointer conversion and alignment]
Date 2018-11-20 08:31 -0500
Organization A noiseless patient Spider
Message-ID <pt12bu$3rp$1@dont-email.me> (permalink)
References (3 earlier) <20181119153734.485dbb156e26d9843e8305f6@g{oogle}mail.com> <4654f0ff-b45f-4e4d-96b8-144fa834586b@googlegroups.com> <20181120004546.f7e51c9afe2dc3146cd4b6f1@gmail.com> <274720c1-99ec-4f48-ad91-c8c1b0b87f23@googlegroups.com> <20181120150538.057a3beae9aea05920bba5fc@g{oogle}mail.com>

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On 11/20/18 07:05, Anton Shepelev wrote:
> James Kuyper:
> 
>>> That answers my question about the meaning of a pointer
>>> correctly alinged for a type.  It is simply a pointer
>>> storing a byte address that is a multiple of the type's
>>> alignment, right?
>>
>> Correct.
> 
> Thank you.  Antoher problem is that the Standard does not
> seem to guarantee that the byte address is preservied in
> one-way pointer conversion, ...

In general, you're right - and I consider that a defect in the standard
because it seems to be universally assumed that all pointer conversions
that the standard allows result in a pointer to the same memory location
- it would be nice if the standard actually said so.
However, the standard does actually say it in one important case: "When
a pointer to an object is converted to a pointer to a character type,
the result points to the lowest addressed byte of the object. Successive
increments of the result, up to the size of the object, yield pointers
to the remaining bytes of the object."(6.3.2.3p7).

A committee member once claimed to me that you could conclude from
6.3.2.3p7 that, for all permitted pointer conversions, (T*)p points at
an object whose first byte is in the same location as the first byte of
the object pointed at by p itself. I don't follow that logic, and asked
him to support that claim, without getting a meaningful response. I
suspect he was assuming that there was a rule for chained pointer
conversions: if (T*)(U*) is permitted, then it is guaranteed to be
equivalent to (T*). No such rule is stated anywhere in the standard.
Conversion chains involving arithmetic types certainly don't obey (T)(U)
being equivalent to (U).

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Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-17 14:38 +0300
  Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-17 17:37 +0300
    Re: Pointer conversion and alignment Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-17 21:01 +0000
      Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 00:43 +0300
        Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 01:20 +0300
          Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-17 18:12 -0500
            Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 02:32 +0300
              Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-17 18:59 -0500
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 12:40 +0300
        Re: Pointer conversion and alignment Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-18 02:14 +0000
          Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 13:23 +0300
            Re: Pointer conversion and alignment Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-18 11:28 +0000
              Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 15:31 +0300
                Re: Pointer conversion and alignment Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-18 15:03 +0000
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 23:00 +0300
      Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 00:49 +0300
  Re: Pointer conversion and alignment Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-11-17 06:52 -0800
    Re: Pointer conversion and alignment Ian Collins <ian-news@hotmail.com> - 2018-11-18 09:18 +1300
      Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-17 13:49 -0800
        Re: Pointer conversion and alignment Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-11-17 13:57 -0800
          Re: Pointer conversion and alignment Ian Collins <ian-news@hotmail.com> - 2018-11-18 11:08 +1300
            Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 01:13 +0300
              Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-17 18:37 -0800
        Re: Pointer conversion and alignment Philipp Klaus Krause <pkk@spth.de> - 2018-11-18 14:14 +0100
  Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-17 10:05 -0500
    Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 01:08 +0300
      Re: Pointer conversion and alignment "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-11-17 14:31 -0800
        Re: Pointer conversion and alignment "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-11-17 16:10 -0800
          Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-18 15:01 +0300
            Re: Pointer conversion and alignment James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-18 07:25 -0500
              Re: Pointer conversion and alignment "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-11-19 21:30 -0800
            Re: Pointer conversion and alignment "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-11-20 14:20 -0800
      Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-17 18:04 -0500
      Re: Pointer conversion and alignment Philipp Klaus Krause <pkk@spth.de> - 2018-11-18 14:18 +0100
      Re: Pointer conversion and alignment scott@slp53.sl.home (Scott Lurndal) - 2018-11-18 19:49 +0000
    Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-11-23 18:27 -0800
      Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-23 21:59 -0500
        Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-11-24 00:32 -0800
          Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-24 08:17 -0500
            Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-11-29 09:55 -0800
              Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-29 21:48 -0500
                Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-05 04:14 -0800
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-12-05 08:14 -0500
                Re: Pointer conversion and alignment Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-05 05:29 -0800
                Re: Pointer conversion and alignment David Brown <david.brown@hesbynett.no> - 2018-12-05 14:44 +0100
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-12-05 21:58 -0500
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-12-05 16:38 +0300
                Re: Pointer conversion and alignment scott@slp53.sl.home (Scott Lurndal) - 2018-12-05 14:23 +0000
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-12-05 14:35 -0800
                Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-08 19:28 -0800
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-12-09 08:18 -0500
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-12-09 14:35 -0500
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-12-09 14:04 -0800
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-12-09 20:40 -0500
                Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-17 07:18 -0800
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-12-17 12:35 -0800
                Re: Pointer conversion and alignment Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-17 12:48 -0800
      Re: Pointer conversion and alignment "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-11-24 18:33 -0800
  My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-19 02:26 +0300
    Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-19 11:08 +0000
      Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-19 15:37 +0300
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-19 15:39 +0300
          Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-19 15:07 +0000
            Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-19 22:24 +0300
              Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-19 12:33 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-20 00:34 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-19 14:38 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-20 00:43 +0000
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-19 21:44 -0500
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jadill33@gmail.com - 2018-11-20 07:11 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] bart4858@gmail.com - 2018-11-20 10:02 -0800
              Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-19 22:20 +0000
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-20 14:01 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Melzzzzz <Melzzzzz@zzzzz.com> - 2018-11-20 11:07 +0000
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-20 15:12 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-20 08:15 -0500
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-20 23:08 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-20 14:13 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-21 16:38 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-21 09:05 -0500
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-21 20:28 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-21 12:58 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-22 01:47 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-21 15:50 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-24 19:37 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-21 21:22 +0000
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-21 01:15 +0000
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-19 15:06 +0000
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] mark.bluemel@gmail.com - 2018-11-19 08:05 -0800
          Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] scott@slp53.sl.home (Scott Lurndal) - 2018-11-19 16:49 +0000
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-19 10:35 -0800
          Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-20 00:45 +0300
            Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-19 14:24 -0800
              Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-20 15:05 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-20 08:31 -0500
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Richard Damon <Richard@Damon-Family.org> - 2018-11-20 20:02 -0500
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-21 22:47 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] jameskuyper@alumni.caltech.edu - 2018-11-21 13:08 -0800
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-22 00:31 +0300
                Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-21 21:36 +0000
      Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-19 16:04 +0300
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-19 14:56 +0000
    Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-24 19:24 +0300
      Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-24 21:31 +0000
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-24 21:46 +0000
        Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-25 01:12 +0300
          Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-11-25 01:39 +0000
            Re: My dynamic arrays module [was:Re: Pointer conversion and alignment] Anton Shepelev <anton.txt@gmail.com> - 2018-11-25 14:19 +0300
  Re: Pointer conversion and alignment jadill33@gmail.com - 2018-11-19 08:44 -0800
    Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-20 00:02 +0300
      Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-19 13:51 -0800
        Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-20 01:08 +0300
          Re: Pointer conversion and alignment jameskuyper@alumni.caltech.edu - 2018-11-19 14:31 -0800
            Re: Pointer conversion and alignment Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-20 15:21 +0300
              Re: Pointer conversion and alignment James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-20 08:59 -0500
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-20 11:06 -0800
                Re: Pointer conversion and alignment jameskuyper@alumni.caltech.edu - 2018-11-20 12:43 -0800
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-20 14:33 -0800
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-21 14:33 +0300
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-21 07:49 -0500
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-21 12:42 -0800
                Re: Pointer conversion and alignment James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-21 08:41 -0500
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-25 15:06 +0300
                Re: Pointer conversion and alignment James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-11-25 10:47 -0500
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@g{oogle}mail.com> - 2018-11-26 12:42 +0300
                Re: Pointer conversion and alignment Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-11-26 03:07 -0800
                Re: Pointer conversion and alignment Keith Thompson <kst-u@mib.org> - 2018-11-26 12:56 -0800
                Re: Pointer conversion and alignment Richard Damon <Richard@Damon-Family.org> - 2018-11-26 18:17 -0500
                Re: Pointer conversion and alignment jameskuyper@alumni.caltech.edu - 2018-11-26 09:06 -0800
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-26 23:52 +0300
                Re: Pointer conversion and alignment jameskuyper@alumni.caltech.edu - 2018-11-26 13:13 -0800
                Re: Pointer conversion and alignment Anton Shepelev <anton.txt@gmail.com> - 2018-11-27 00:31 +0300
                Re: Pointer conversion and alignment jameskuyper@alumni.caltech.edu - 2018-11-26 14:15 -0800
      Re: Pointer conversion and alignment jadill33@gmail.com - 2018-11-19 14:33 -0800

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