Re: C pointer semantics with dynamically allocated struct

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.c
Subject	Re: C pointer semantics with dynamically allocated struct
Date	2015-10-02 21:24 +0100
Organization	A noiseless patient Spider
Message-ID	<877fn5qas8.fsf@bsb.me.uk> (permalink)
References	(16 earlier) <c7584161-0233-4327-8792-cbba35ebcbaa@googlegroups.com> <874mi9s415.fsf@bsb.me.uk> <9e564d49-c531-420a-8d50-fe5fba789415@googlegroups.com> <87mvw1qggo.fsf@bsb.me.uk> <376c05c3-ee5a-4cc9-b910-6a9d753aa4f1@googlegroups.com>

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supercat@casperkitty.com writes:

> On Friday, October 2, 2015 at 1:21:44 PM UTC-5, Ben Bacarisse wrote:
>> supercat writes:
>> > On Friday, October 2, 2015 at 10:07:16 AM UTC-5, Ben Bacarisse wrote:
>> >>      For obvious reasons, the C standard doesn't say what the result
>> >> will actually be in most cases, but it's no less legal or valid than
>> >> writing CHAR_MAX + 1.
>> >
>> > When, in C, did it first become possible...
>
>> I don't understand the question, mainly because I don't know what you
>> means by equivalent here.  Maybe if you gave a full example of what you
>> think is wrong or has changed about C, it would be clear to me.
>
> I suppose one possible point of confusion is what is meant by "most cases".
> Many compilers document the way in which they store various types precisely
> even in cases where the Standard does not require it.  I would suggest that
> if an implementation documents precisely how two types are stored, there
> isn't any wiggle room for what a C89 compiler will do if one type is stored
> to the union and the other is read out.  Most code which would use unions
> for type punning is targeted toward such implementations, so in at least
> some sense the behavior was defined in "most cases".
>
>> > I recall that a major part of the C
>> > philosophy was that the state of every object can be decomposed into a
>> > sequence of "char" values.  The Strict Aliasing Rule of C99 allows for
>> > objects to have additional "hidden" state, but I don't think K&R C nor
>> > C89 allowed that.
>> 
>> Again, I'm not sure what this hidden state is.  Do you mean the
>> effective type of the object?  If so, what point are you making in
>> regard to unions?
>
> In cases where two types' representations are completely documented, if
> storing some value of one type in a union would result in a program
> executing with completely defined behavior, and storing a value of some
> other type which is documented as having the same bit-level representation
> would invoke Undefined Behavior, that would imply that a compiler is allowed
> to keep track of what type was stored in the union even though there is
> no defined mechanism by which that could happen.
>
>> > If "sizeof (float)" and "sizeof (long)" are both 4, what room would there
>> > have been for a compiler given:
>> >
>> >     union { float f; long l; } u;
>> >     u.f = 1.0;
>> >     printf("%ld", u.l);
>> >
>> > to do anything other than have "l" reinterpret the bits of 1.0 as a
>> > "long"?
>> 
>> And now it is the hypothetical that is confusing me.  I don't think
>> there has ever been any permission for the above code to anything but
>> reinterpret the bits of u.f and a long.  Do you think I've been saying
>> otherwise?  Do you think there is or once was such permission?
>
> Some people seem to think that such permission exists, and that behavior is
> only defined in cases where values are read and written as the same
> type.

Saying that something is not undefined behaviour does not mean that it
is defined!

I see zero wriggle room for anyone to say the access of u.l above is
undefined behaviour (though if anyone does, please say chip in say why).
But that does not mean that u.l is defined, or well-defined or
fully-defined or any other similar natural language term.  The result
depends on all sorts of things and the standard does not ask for all
these things to be documented, which is why it is unspecified behaviour
rather than implementation-defined behaviour.

I know that unspecified behaviour can include cases that are truly
undefined.  For example if long has padding bits and trap
representations the result of evaluating u.l may be undefined behaviour,
but that is not due to the union access.

> Prior to C99 I don't think anyone perceived there as being any wiggle room,
> and I don't know that any compilers behaved as though there were; in C++,
> type punning in the general case (where one or both types may have virtual
> members) invokes Undefined Behavior, and I don't think the Standard has
> done anything to clarify that in cases where two types have documented
> representations, implementations are required to behave in terms of those
> representations, and type punning may only trigger Undefined Behavior in
> cases where the bytes interpreted as an rvalue of some type could hold a
> trap representation for that type.

Sorry, I can't see where you stop talking about C++ there so I don't know
how to comment.

> As it is, there's still a lot of murkiness about things like:
>
>     union U { float f; long l; } u;
>     u.l = 1234;
>     scanf("%f", &u.f);
>     printf("%08lX", u.l);
>
> The intention of scanf is that it should store some value into u.f, but
> scanf doesn't store to a (union U*) but instead to a "float*", so it's
> not clear whether a compiler would be required to store 1234 into the
> memory associated with "u" before the scanf and read it back
> afterward.

This code contravenes a "shall" in the standard by not passing an
unsigned long as printf's second argument but I don't suppose that is
the murkiness you are referring to.

I don't see what you are worried about.  Setting *&u.f via scanf is
fine.  Reading u.l is also fine, but the result is unspecified and it
could be catastrophic if long has trap representations.  I don't see why
you think 1234 needs to be read back (thought it might be, of course).

-- 
Ben.

Thread

Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-09-29 09:49 -0700
  Re: C pointer semantics with dynamically allocated struct wssimms@gmail.com - 2015-09-30 21:18 -0700
    Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-01 09:35 -0700
      Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-01 09:41 -0700
        Re: C pointer semantics with dynamically allocated struct gazelle@shell.xmission.com (Kenny McCormack) - 2015-10-01 18:34 +0000
          Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-01 12:02 -0700
    Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-02 13:03 +0000
      Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-02 06:20 -0700
        Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 16:07 +0100
          Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-02 08:46 -0700
            Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 17:28 +0100
              Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-02 10:30 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 20:32 +0100
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-02 12:58 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 22:06 +0100
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-03 09:31 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-03 14:31 -0700
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-03 09:27 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-03 20:36 +0100
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-03 13:00 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-03 23:37 +0100
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-03 17:07 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-03 17:42 -0700
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-03 17:49 -0700
                Re: C pointer semantics with dynamically allocated struct Richard Damon <Richard@Damon-Family.org> - 2015-10-03 23:28 -0400
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-04 00:10 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-04 13:24 +0100
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-04 14:07 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-04 14:40 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-04 18:04 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-04 20:10 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-04 22:15 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-05 08:53 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-06 08:45 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-06 12:34 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-06 17:16 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-06 21:47 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-07 11:05 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-07 11:47 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-07 13:50 -0700
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-07 18:10 -0400
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-07 16:10 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-07 16:33 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-08 09:08 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-08 10:43 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-08 11:50 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-08 12:19 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-07 15:32 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-07 16:21 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-08 08:54 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-08 11:15 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-08 12:38 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-08 13:30 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-08 14:15 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-08 14:53 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-08 15:23 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-08 17:24 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-09 08:02 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-09 09:02 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-09 12:43 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-09 14:21 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-09 15:14 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-13 18:37 -0700
                Re: C pointer semantics with dynamically allocated struct Martin Shobe <martin.shobe@yahoo.com> - 2015-10-07 20:56 -0500
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-07 19:41 -0700
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-07 23:15 -0400
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-14 10:05 +0000
                Re: C pointer semantics with dynamically allocated struct Richard Heathfield <rjh@cpax.org.uk> - 2015-10-14 11:23 +0100
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-14 08:24 -0700
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-16 11:12 +0000
                Re: C pointer semantics with dynamically allocated struct Gareth Owen <gwowen@gmail.com> - 2015-10-16 21:55 +0100
                Re: C pointer semantics with dynamically allocated struct Les Cargill <lcargill99@comcast.com> - 2015-10-16 22:08 -0500
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-14 11:44 -0400
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-14 11:12 -0700
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-07 10:34 +0000
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-07 07:23 -0400
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-07 09:53 -0700
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-14 10:13 +0000
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-14 11:36 -0400
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-04 13:35 +0100
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-04 06:23 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-04 15:34 +0100
                Re: C pointer semantics with dynamically allocated struct "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-10-04 08:07 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-04 14:42 +0000
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-04 15:37 +0000
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-05 00:33 +0100
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-14 10:20 +0000
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-14 13:55 +0100
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 22:06 -0700
                Re: C pointer semantics with dynamically allocated struct raltbos@xs4all.nl (Richard Bos) - 2015-10-14 10:30 +0000
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-14 08:39 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-14 23:47 +0000
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-15 10:20 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-15 11:10 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-15 12:11 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-15 12:35 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-15 13:52 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-15 14:35 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-15 15:51 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-16 06:48 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-16 08:50 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-16 10:06 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-16 12:45 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-16 13:56 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-16 14:29 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-16 14:52 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-16 15:32 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-16 15:59 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-17 00:03 +0000
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-17 00:08 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 15:26 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-17 16:38 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-16 23:43 +0000
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-16 23:57 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 14:50 -0700
                Re: C pointer semantics with dynamically allocated struct Ian Collins <ian-news@hotmail.com> - 2015-10-18 10:55 +1300
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-17 18:24 -0400
                Re: C pointer semantics with dynamically allocated struct Richard Damon <Richard@Damon-Family.org> - 2015-10-17 18:39 -0400
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-17 18:56 -0400
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 16:17 -0700
                Re: C pointer semantics with dynamically allocated struct James Kuyper <jameskuyper@verizon.net> - 2015-10-18 11:46 -0400
                Re: C pointer semantics with dynamically allocated struct Richard Damon <Richard@Damon-Family.org> - 2015-10-17 19:44 -0400
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-17 16:48 -0700
                Re: C pointer semantics with dynamically allocated struct Richard Heathfield <rjh@cpax.org.uk> - 2015-10-18 01:14 +0100
                Re: C pointer semantics with dynamically allocated struct Richard Damon <Richard@Damon-Family.org> - 2015-10-17 20:22 -0400
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-17 17:26 -0700
                Re: C pointer semantics with dynamically allocated struct Richard Heathfield <rjh@cpax.org.uk> - 2015-10-18 01:44 +0100
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 20:09 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-18 11:24 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-19 04:42 +0000
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-19 16:24 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-20 02:20 +0000
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-19 19:53 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-20 09:41 +0000
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 19:53 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 16:07 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-17 14:55 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-18 04:28 +0000
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-15 12:49 -0700
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-15 12:26 -0700
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-15 12:48 -0700
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-17 08:21 -0700
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 22:23 -0700
          Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-02 09:10 -0700
            Re: C pointer semantics with dynamically allocated struct Martin Shobe <martin.shobe@yahoo.com> - 2015-10-02 11:58 -0500
              Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-02 11:38 -0700
                Re: C pointer semantics with dynamically allocated struct Martin Shobe <martin.shobe@yahoo.com> - 2015-10-05 09:36 -0500
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-12 09:47 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-13 02:51 +0000
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-12 23:45 -0700
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-15 13:54 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-16 01:07 +0000
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-19 15:33 -0700
            Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 19:21 +0100
              Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-02 12:10 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 21:24 +0100
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-02 14:32 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-02 23:43 +0100
                Re: C pointer semantics with dynamically allocated struct supercat@casperkitty.com - 2015-10-02 16:49 -0700
                Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-03 02:01 +0100
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-03 00:38 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-02 16:10 -0700
                Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 21:54 -0700
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-05 08:19 -0700
          Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-02 15:16 -0700
            Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-02 22:52 +0000
              Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-03 00:48 -0700
                Re: C pointer semantics with dynamically allocated struct glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-10-03 08:22 +0000
                Re: C pointer semantics with dynamically allocated struct Keith Thompson <kst-u@mib.org> - 2015-10-03 12:05 -0700
              Re: C pointer semantics with dynamically allocated struct Richard Damon <Richard@Damon-Family.org> - 2015-10-03 16:38 -0400
            Re: C pointer semantics with dynamically allocated struct Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-10-03 00:00 +0100
              Re: C pointer semantics with dynamically allocated struct Tim Rentsch <txr@alumni.caltech.edu> - 2015-10-04 22:16 -0700

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