Re: Issue on assigning address to pointers

From	James Kuyper <jameskuyper@verizon.net>
Newsgroups	comp.lang.c
Subject	Re: Issue on assigning address to pointers
Date	2015-11-17 15:32 -0500
Organization	A noiseless patient Spider
Message-ID	<n2g2ph$b7k$1@dont-email.me> (permalink)
References	<dc62f43a-1725-496b-b36a-c3e196015b7d@googlegroups.com> <9ptm4b9aist9nba86pj9l086mamsqaa3or@4ax.com>

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On 11/17/2015 02:15 PM, Geoff wrote:
> On Tue, 17 Nov 2015 08:49:29 -0800 (PST), Alla _
> <modelling.data@gmail.com> wrote:
> 
>> int numbers[8];
>> int *ptr;
>>
>> ptr = numbers + 8; // to point at a value stored at numbers[8]
>>
> 
> If you are seeing code that looks like this without an caveats then
> you should discard it immediately. The author is either being tricky
> or he doesn't know what he is doing.

The comment is wrong and misleading, but the code is fine.

> There are 8 elements in the numbers array, 0 through 7. Pointing to a
> ninth element is an error.

No, it is not. Pointing one past the end of an array is explicitly
permitted by the standard (though a strict reading of 6.5.6p8 justifies
the unintended conclusion that it can only be accessed by writing
(numbers+7)+1).
-- 
James Kuyper

Thread

Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 08:49 -0800
  Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 12:36 -0500
    Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 17:47 +0000
      Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:34 -0800
        Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 12:16 -0800
        Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 15:23 -0500
    Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:33 -0800
  Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 09:41 -0800
    Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 10:03 -0800
      Re: Issue on assigning address to pointers glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-11-17 20:31 +0000
        Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 12:53 -0800
    Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:32 -0800
      Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:45 +0000
        Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:53 -0800
        Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 15:05 -0800
          Re: Issue on assigning address to pointers Philip Lantz <prl@canterey.us> - 2015-11-19 21:16 -0800
        Re: Issue on assigning address to pointers Anand Hariharan <mailto.anand.hariharan@gmail.com> - 2015-11-17 15:47 -0800
        Re: Issue on assigning address to pointers Barry Schwarz <schwarzb@dqel.com> - 2015-11-17 15:53 -0800
          Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-18 04:05 +0000
      Re: Issue on assigning address to pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 19:41 +0000
  Re: Issue on assigning address to pointers Stephen Sprunk <stephen@sprunk.org> - 2015-11-17 12:17 -0600
    Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:21 +0000
      Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 10:36 -0800
        Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:46 +0000
          Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:49 -0800
        Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:47 -0800
          Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:51 +0000
            Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:55 -0800
          Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 11:59 -0800
      Re: Issue on assigning address to pointers Stephen Sprunk <stephen@sprunk.org> - 2015-11-17 12:58 -0600
        Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 19:12 +0000
      Re: Issue on assigning address to pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 19:33 +0000
    Re: Issue on assigning address to pointers Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-11-17 13:25 -0500
  Re: Issue on assigning address to pointers Richard Heathfield <rjh@cpax.org.uk> - 2015-11-17 18:31 +0000
    Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:39 -0800
    Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-17 10:40 -0800
      Re: Issue on assigning address to pointers Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-11-17 19:40 +0000
  Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 11:15 -0800
    Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 15:32 -0500
    Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-17 15:09 -0800
      Re: Issue on assigning address to pointers supercat@casperkitty.com - 2015-11-17 15:41 -0800
        Re: Issue on assigning address to pointers Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-11-17 21:28 -0800
          Re: Issue on assigning address to pointers supercat@casperkitty.com - 2015-11-17 23:18 -0800
      Re: Issue on assigning address to pointers Geoff <geoff@invalid.invalid> - 2015-11-17 17:18 -0800
        Re: Issue on assigning address to pointers James Kuyper <jameskuyper@verizon.net> - 2015-11-17 22:37 -0500
  Re: Issue on assigning address to pointers Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-11-18 11:27 +0100
    Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-18 06:13 -0800
  Re: Issue on assigning address to pointers guinness.tony@gmail.com - 2015-11-24 02:46 -0800
    Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-24 09:21 -0800
  Re: Issue on assigning address to pointers John Bode <jfbode1029@gmail.com> - 2015-11-24 05:01 -0800
    Re: Issue on assigning address to pointers Keith Thompson <kst-u@mib.org> - 2015-11-24 09:22 -0800
  Re: Issue on assigning address to pointers John Bode <jfbode1029@gmail.com> - 2015-11-24 06:47 -0800
    Re: Issue on assigning address to pointers Alla _ <modelling.data@gmail.com> - 2015-11-25 06:44 -0800

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