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Re: Pointer Arithmetic & UB

From glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups comp.lang.c
Subject Re: Pointer Arithmetic & UB
Date 2012-12-21 23:52 +0000
Organization Aioe.org NNTP Server
Message-ID <kb2sod$13n$1@speranza.aioe.org> (permalink)
References (8 earlier) <kaodld$4gb$1@dont-email.me> <kavcm1$pv9$1@dont-email.me> <kb160d$kpg$1@dont-email.me> <kfn4njf5cna.fsf@x-alumni2.alumni.caltech.edu> <kb2phn$5fl$1@dont-email.me>

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Shao Miller <sha0.miller@gmail.com> wrote:

> On 12/21/2012 16:16, Tim Rentsch wrote:
(snip)
>> IMO this conclusion is wrong.  The consequences of volatile access (ie,
>> the extra-linguistic side effects) are outside the domain of 6.5p2,
>> because it is concerned only with program expressions, not other
>> unknown memory changes.  This view is explained in more detail in my
>> response to Ben Bacarisse in this thread.
 
> I read the other response.  And what about if 'x' and "foo counter" are 
> the same scalar?  Regardless of that or any other example, N1570's 
> informative Annex I, point 2 includes:
 
>   "An ??????unordered?????? binary operator (not comma, &&, or ||) contains a 
> side effect to an lvalue in one operand, and a side effect to, or an 
> access to the value of, the identical lvalue in the other operand (6.5)."

This seems to be for expressions like (x++)+(x).

Also, it seems to indicate that access isn't a side affect.
 
> Informative Annex J "Portability issues", J.2 "Undefined behavior", 
> point 1 includes:
 
>   "A side effect on a scalar object is unsequenced relative to either a 
> different side effect on the same scalar object or a value computation 
> using the value of the same scalar object (6.5)."
 
> Why wouldn't the Standard discuss "stored value" or "modification" 
> instead of using the looser "side effect"?  5.1.2.3p2:
 
>   "Accessing a volatile object, modifying an object, modifying a file, 
> or calling a function that does any of those operations are all side 
> effects,12) which are changes in the state of the execution environment. 
> Evaluation of an expression in general includes both value computations 
> and initiation of side effects. Value computation for an lvalue 
> expression includes determining the identity of the designated object."

Is there any indication in the standard on what "side affect" means
for volatile data?  I/O registers have been mentioned in the discussion,
but is that in the standard?

There have been systems with self-incrementing or self-decrementing
memory locations. If one was used for a volatile variable, then
there is an obvious side effect.
 
> There is no need for any extra-linguistic side effect, since "accessing 
> a volatile object" is a side effect by its own right.  I think examples 
> can still be helpful, though.
 
> 6.7.3p7:
 
>   "An object that has volatile-qualified type may be modified in ways 
> unknown to the implementation or have other unknown side effects. 
> Therefore any expression referring to such an object shall be evaluated 
> strictly according to the rules of the abstract machine, as described in 
> 5.1.2.3. Furthermore, at every sequence point the value last stored in 
> the object shall agree with that prescribed by the abstract machine, 
> except as modified by the unknown factors mentioned previously.134) What 
> constitutes an access to an object that has volatile-qualified type is 
> implementation-defined."

Sometimes "access" means fetch but not store. I am not so sure
in this case either way.
 
> If the last sentence here means that an implementation has license to 
> redefine that one or both of a read or a store is _not_ an access to a 
> volatile-qualified type, then it cannot abide by the second sentence, 
> which involves the semantics of reading and modifying.  If one accepts 
> that the final sentence is not allowing for a redefinition of "access," 
> then it must be allowing for a definition of what [else] _constitutes_ 
> an access, such as:
 
> - A clock tick increments the stored value of a tick-counter
> - A read of a usage-counter increments the stored value of the usage-counter
> - A read of the value of an object used for obtaining random values 
> causes the object's stored value to change to a new random value

Seems to me that these all have to be implementation dependent
(or implementation defined), in which case the effects and meaning
of "volatile" should also be so defined.
 
> "Undefined" by the Standard can obviously be defined by the 
> implementation, but need not be, which is why I'd suggest that it's 
> undefined.  (The implementation doesn't have to know, document, or be 
> consistent about it.)

-- glen

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Thread

Pointer Arithmetic & UB Edward Rutherford <edward.p.rutherford79@REMOVETHIS.gmail.com> - 2012-12-10 17:14 +0000
  Re: Pointer Arithmetic & UB "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-12-10 09:35 -0800
  Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-10 12:55 -0500
    Re: Pointer Arithmetic & UB Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-10 13:25 -0500
      Re: Pointer Arithmetic & UB falk@rahul.net (Edward A. Falk) - 2012-12-11 00:46 +0000
        Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-10 21:28 -0500
          Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-12 14:36 -0500
            Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-12 20:35 +0000
            Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-12 15:57 -0500
            Re: Pointer Arithmetic & UB Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-12 16:02 -0500
              Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-12 16:13 -0500
                Re: Pointer Arithmetic & UB Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-12 21:18 -0500
                Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-12 22:42 -0500
                Re: Pointer Arithmetic & UB Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-12-17 12:04 +0200
                Re: Pointer Arithmetic & UB Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-17 08:47 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-17 14:58 +0000
                Re: Pointer Arithmetic & UB Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-17 10:59 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-17 17:26 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2012-12-17 19:33 -0500
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-20 11:00 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-20 10:03 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-20 22:02 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-21 13:09 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-21 22:40 +0000
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-21 23:39 -0500
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-22 06:50 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-22 00:15 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-22 10:34 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-22 09:32 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-23 09:38 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-23 09:55 -0800
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-26 13:35 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-27 09:03 -0800
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-27 21:31 -0500
                Re: Pointer Arithmetic & UB Philip Lantz <prl@canterey.us> - 2012-12-28 01:55 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-29 13:43 -0800
                Re: Pointer Arithmetic & UB Philip Lantz <prl@canterey.us> - 2012-12-28 01:39 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-28 11:31 +0000
                Re: Pointer Arithmetic & UB Keith Thompson <kst-u@mib.org> - 2012-12-28 08:47 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-29 17:45 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-30 04:06 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-02 10:08 -0800
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-26 13:29 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-27 07:55 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-27 08:01 -0800
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-27 21:10 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-29 18:03 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-23 03:48 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-23 10:22 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-12-27 10:34 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-27 10:16 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-10 17:26 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-12 12:38 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-12 20:50 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-13 13:07 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-13 22:11 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-14 11:11 -0800
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-12 18:32 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-13 00:34 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-13 16:40 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-14 00:01 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-13 19:20 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-14 01:03 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-13 20:41 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-14 03:19 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-13 23:36 -0500
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-13 23:43 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-14 13:20 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-14 20:02 -0500
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-15 21:20 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-14 10:23 -0800
                Re: Pointer Arithmetic & UB 88888 Dihedral <dihedral88888@googlemail.com> - 2013-01-15 10:53 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-15 22:39 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-15 22:28 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-15 23:35 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-16 23:38 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-18 09:37 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-14 10:29 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-15 21:38 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-15 23:57 -0800
                Re: Pointer Arithmetic & UB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2013-01-16 15:34 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-16 11:15 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-16 10:28 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-16 19:09 +0000
                Re: Pointer Arithmetic & UB Richard Damon <news.x.richarddamon@xoxy.net> - 2013-01-16 23:26 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-18 10:08 -0800
                Re: Pointer Arithmetic & UB Keith Thompson <kst-u@mib.org> - 2013-01-18 11:33 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-18 14:00 -0800
                Re: Pointer Arithmetic & UB Richard Damon <news.x.richarddamon@xoxy.net> - 2013-01-19 09:10 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-20 13:35 -0800
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-20 20:15 -0500
                Re: Pointer Arithmetic & UB Richard Damon <news.x.richarddamon@xoxy.net> - 2013-01-20 21:05 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-21 09:43 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-18 11:13 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-18 20:59 +0000
                Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2013-01-18 16:24 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-19 00:17 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-19 11:22 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-20 14:51 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-21 00:07 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-21 10:05 -0800
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2013-01-21 20:19 +0000
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2013-01-21 23:20 -0800
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2013-01-18 17:48 -0500
                Re: Pointer Arithmetic & UB 88888 Dihedral <dihedral88888@googlemail.com> - 2013-01-18 13:13 -0800
                Re: Pointer Arithmetic & UB Robert Wessel <robertwessel2@yahoo.com> - 2012-12-20 12:21 -0600
                Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-20 13:40 -0500
                Re: Pointer Arithmetic & UB Robert Wessel <robertwessel2@yahoo.com> - 2012-12-20 13:32 -0600
                Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-20 14:58 -0500
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-20 21:54 +0000
                Re: Pointer Arithmetic & UB Lanarcam <lanarcam1@yahoo.fr> - 2012-12-20 19:49 +0100
                Re: Pointer Arithmetic & UB Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-12-21 02:38 +0200
                Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-21 14:33 -0500
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2012-12-21 03:18 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-21 13:16 -0800
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2012-12-21 17:57 -0500
                Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-21 23:52 +0000
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2012-12-21 19:47 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-21 22:54 -0800
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2012-12-22 03:31 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-22 09:16 -0800
                Re: Pointer Arithmetic & UB Shao Miller <sha0.miller@gmail.com> - 2012-12-24 04:23 -0500
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-27 11:07 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-17 02:33 -0800
                Re: Pointer Arithmetic & UB Tim Rentsch <txr@alumni.caltech.edu> - 2012-12-17 02:18 -0800
        Re: Pointer Arithmetic & UB Noob <root@127.0.0.1> - 2012-12-11 11:36 +0100
          Re: Pointer Arithmetic & UB "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-12-11 10:00 -0800
            Re: Pointer Arithmetic & UB Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-12-17 12:11 +0200
        Re: Pointer Arithmetic & UB Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-11 15:27 -0500
          Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-11 21:09 +0000
        Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-12 14:30 -0500
          Re: Pointer Arithmetic & UB Keith Thompson <kst-u@mib.org> - 2012-12-12 11:42 -0800
          Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-12 17:12 -0500
          Re: Pointer Arithmetic & UB Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-12-17 12:16 +0200
  Re: Pointer Arithmetic & UB Prathamesh Kulkarni <bilbotheelffriend@gmail.com> - 2012-12-10 12:04 -0800
    Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-10 15:29 -0500
      Re: Pointer Arithmetic & UB Prathamesh Kulkarni <bilbotheelffriend@gmail.com> - 2012-12-10 12:44 -0800
        Re: Pointer Arithmetic & UB Prathamesh Kulkarni <bilbotheelffriend@gmail.com> - 2012-12-10 12:47 -0800
          Re: Pointer Arithmetic & UB James Kuyper <jameskuyper@verizon.net> - 2012-12-10 16:02 -0500
            Re: Pointer Arithmetic & UB Prathamesh Kulkarni <bilbotheelffriend@gmail.com> - 2012-12-10 13:08 -0800
              Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-12 14:26 -0500
            Re: Pointer Arithmetic & UB Greg Martin <greg@softsprocket.com> - 2012-12-10 14:55 -0800
        Re: Pointer Arithmetic & UB Sjouke Burry <s@b> - 2012-12-10 21:18 +0000
        Re: Pointer Arithmetic & UB falk@rahul.net (Edward A. Falk) - 2012-12-11 00:48 +0000
      Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-10 21:01 +0000
      Re: Pointer Arithmetic & UB Ken Brody <kenbrody@spamcop.net> - 2012-12-12 14:24 -0500
        Re: Pointer Arithmetic & UB Robert Wessel <robertwessel2@yahoo.com> - 2012-12-12 14:34 -0600
        Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-12 20:45 +0000
          Re: Pointer Arithmetic & UB Robert Wessel <robertwessel2@yahoo.com> - 2012-12-12 15:29 -0600
            Re: Pointer Arithmetic & UB glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-12-13 02:02 +0000
        Re: Pointer Arithmetic & UB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-12-17 05:57 -0800
    Re: Pointer Arithmetic & UB pete <pfiland@mindspring.com> - 2012-12-10 20:20 -0500

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