Re: Types in C

From	Ian Collins <ian-news@hotmail.com>
Newsgroups	comp.lang.c
Subject	Re: Types in C
Date	2011-05-24 13:47 +1200
Message-ID	<940h22Ft2pU21@mid.individual.net> (permalink)
References	(6 earlier) <50d915539d62563-19304@gmail.com> <9405q4Ft2pU12@mid.individual.net> <56d1adcc041e87f-81300@gmail.com> <940aukFt2pU18@mid.individual.net> <e086f8c7d12fb8d-c2f4b@gmail.com>

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On 05/24/11 01:27 PM, Uncle Steve wrote:
> On Tue, May 24, 2011 at 12:03:32PM +1200, Ian Collins wrote:
>> On 05/24/11 11:33 AM, Uncle Steve wrote:
>>
>>> This produces an error if there is no struct bar definition because
>>> the compiler cannot guess what code to generate.  Hence, it would
>>> never be encountered at run-time.  Please correct me if this is not
>>> the case.
>>
>> It is, but a pointer to an incomplete may be used.
>
> I see the logic, as pointers ought to be the same size regardless of
> the thing they point to.  But of what use is it to define an
> incomplete pointer type?  All you can do is suppress warnings by
> casting any assignment to a complete type that the compiler knows
> about.

I wrote "pointer to an incomplete type" (OK, I omitted "type"!).

A pointer to an incomplete type is frequently used as an handle type to 
avoid exposing the type definition to the user.  FILE* is the most 
obvious example.

-- 
Ian Collins

Thread

Types in C jacob navia <jacob@spamsink.net> - 2011-05-22 21:29 +0200
  Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-22 12:48 -0700
  Re: Types in C Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-22 23:03 +0100
    Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 10:35 +0200
      Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 08:40 -0700
        Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 17:19 +0000
          Re: Types in C John Gordon <gordon@panix.com> - 2011-05-23 17:54 +0000
            Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 11:33 -0700
              Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 11:44 -0700
            Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 19:08 +0000
          Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 20:50 +0200
            Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 12:11 -0700
              Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 19:45 +0000
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 13:03 -0700
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 22:25 +0200
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 14:38 -0700
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 23:45 +0200
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:02 +0000
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 00:10 +0200
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 22:12 +0200
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-23 13:27 -0700
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 22:33 +0200
                Re: Types in C Martin Ambuhl <mambuhl@earthlink.net> - 2011-05-24 03:17 -0400
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 10:55 +0200
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:29 +1200
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 23:42 +0200
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:51 +1200
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 00:04 +0200
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:57 +1200
                Re: Types in C David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 19:33 -0500
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 08:27 -0700
                Re: Types in C Tim Rentsch <txr@alumni.caltech.edu> - 2011-05-31 00:40 -0700
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-31 11:32 +0200
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-31 11:30 -0700
                Re: Types in C Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-01 01:23 -0700
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 16:51 -0400
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 09:25 +1200
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-23 23:40 +0200
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 08:36 -0700
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 17:53 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:24 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:23 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:57 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:22 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 03:46 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 00:24 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 04:44 +0000
                Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 07:46 -0400
                Re: Types in C James Kuyper <jameskuyper@verizon.net> - 2011-05-24 07:48 -0400
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:35 +1200
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:38 +0000
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 10:53 +1200
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:17 +0000
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 11:24 +1200
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:39 +0000
                Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-24 11:23 +0200
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 08:46 -0700
                Re: Types in C Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-05-24 09:14 -0700
                Re: Types in C Michael Press <rubrum@pacbell.net> - 2011-05-28 21:50 -0700
                Re: Types in C "io_x" <a@b.c.invalid> - 2011-06-07 19:50 +0200
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:33 -0400
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 12:03 +1200
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:27 -0400
                Re: Types in C Ian Collins <ian-news@hotmail.com> - 2011-05-24 13:47 +1200
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 23:45 -0400
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 00:07 -0700
                Re: Types in C James Kuyper <jameskuyper@verizon.net> - 2011-05-24 08:05 -0400
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 19:54 -0500
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:03 -0400
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 22:12 -0500
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 00:03 -0400
                Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 00:19 -0400
                Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 00:20 -0400
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-24 00:46 -0500
                Re: Types in C pete <pfiland@mindspring.com> - 2011-05-24 07:36 -0400
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 10:58 -0400
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 09:40 -0700
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:36 -0400
                Re: Types in C David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 16:50 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:10 -0400
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 18:19 -0700
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:42 -0400
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-24 23:47 -0500
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-25 10:13 -0400
                Re: Types in C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-24 22:19 -0600
                Re: Types in C Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-25 07:04 +0100
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-25 08:53 -0700
                Re: Types in C Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2011-05-25 10:11 -0600
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 09:02 -0700
                Re: Types in C James Kuyper <jameskuyper@verizon.net> - 2011-05-24 07:37 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:02 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 18:15 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 22:25 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 19:39 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-23 23:57 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 21:10 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 01:58 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-23 23:56 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 04:32 +0000
                Re: Types in C "BartC" <bc@freeuk.com> - 2011-05-25 01:29 +0100
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 22:20 -0500
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-23 22:42 -0500
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 00:07 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 04:44 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 10:24 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-24 16:50 +0000
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 21:16 -0400
                Re: Types in C Seebs <usenet-nospam@seebs.net> - 2011-05-25 03:36 +0000
                Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-24 01:26 -0500
                Re: Types in C Uncle Steve <stevet810@gmail.com> - 2011-05-24 11:04 -0400
                Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-24 09:06 -0700
            Re: Types in C David Thompson <dave.thompson2@verizon.net> - 2011-06-01 16:33 -0400
  Re: Types in C Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-05-30 22:42 +0200
    Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-30 17:45 -0500
      Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-05-31 08:47 -0700
        Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-31 13:54 -0400
    Re: Types in C jacob navia <jacob@spamsink.net> - 2011-05-31 00:16 +0200
      Re: Types in C Shao Miller <sha0.miller@gmail.com> - 2011-05-30 18:30 -0500
      Re: Types in C Marcin Grzegorczyk <mgrzegor@poczta.onet.pl> - 2011-06-02 22:44 +0200
        Re: Types in C jacob navia <jacob@spamsink.net> - 2011-06-02 22:49 +0200
          Re: Types in C Keith Thompson <kst-u@mib.org> - 2011-06-02 15:26 -0700

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