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Re: Passing an integer to a function that accepts a void pointer

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Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> writes:
> In article <iqge5d$h58$1@dont-email.me>,
>  Eric Sosman <esosman@ieee-dot-org.invalid> wrote:
>> On 5/11/2011 9:46 AM, Columbus sailed the ocean China Blue wrote:
>> > In article<slrnisl271.p2s.fis@iris.zem.fi>,
>> >   Heikki Kallasjoki<see@end.of.message.invalid>  wrote:
>> >> [...]
>> >> In other words, the conversion to intptr_t and back is safe only for
>> >> valid pointers.  Arbitrary integer values, even if they are stored in an
>> >> intptr_t object, are not guaranteed to be safely convertible to
>> >> pointers.
>> >
>> > That's nice. Any compiler that screws this up will break so much software 
>> > that
>> > it will be rejected.
>> 
>>      This is how bad code hurts better code.  Suppose you're a compiler
>> writer, and you've figured out a nifty little optimization that reduces
>> the time for pointer operations by X% but makes pointer/integer
>
> Because this is irrelevant. Interfaces that allow integers to be
> passed through as (void*) also promise they make no changes to
> the void pointers, that they are passed through unchanged.

Do you have a concrete example of an interface that expects a void*
argument, and depends on the ability to convert an arbitrary integer
value to a pointer without loss of information?

> It's becoming clear that a large group of 'C experts' have no
> experience how C is actually used. Feel free to whinge about
> this amongst yourself, but be aware you will have no effect on
> the rest of the world.

This would be a lot clearer if you'd back up your specific claims.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Nokia
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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Passing an integer to a function that accepts a void pointer pozz <pozzugno@gmail.com> - 2011-05-11 03:01 -0700
  Re: Passing an integer to a function that accepts a void pointer Tom St Denis <tom@iahu.ca> - 2011-05-11 03:52 -0700
    Re: Passing an integer to a function that accepts a void pointer pete <pfiland@mindspring.com> - 2011-05-11 08:10 -0400
    Re: Passing an integer to a function that accepts a void pointer pozz <pozzugno@gmail.com> - 2011-05-11 18:28 +0200
      Re: Passing an integer to a function that accepts a void pointer Shao Miller <sha0.miller@gmail.com> - 2011-05-11 22:10 -0500
        Re: Passing an integer to a function that accepts a void pointer pozz <pozzugno@gmail.com> - 2011-05-12 19:44 +0200
          Re: Passing an integer to a function that accepts a void pointer Shao Miller <sha0.miller@gmail.com> - 2011-05-12 14:16 -0400
            Re: Passing an integer to a function that accepts a void pointer pozz <pozzugno@gmail.com> - 2011-05-12 21:21 +0200
              Re: Passing an integer to a function that accepts a void pointer Shao Miller <sha0.miller@gmail.com> - 2011-05-12 16:05 -0400
                Re: Passing an integer to a function that accepts a void pointer pozz <pozzugno@gmail.com> - 2011-05-13 23:39 +0200
                Re: Passing an integer to a function that accepts a void pointer Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-14 09:41 +0100
          Re: Passing an integer to a function that accepts a void pointer Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-12 22:07 -0400
            Re: Passing an integer to a function that accepts a void pointer pozz <pozzugno@gmail.com> - 2011-05-13 23:12 +0200
              Re: Passing an integer to a function that accepts a void pointer Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-13 23:30 -0400
  Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-11 04:03 -0700
    Re: Passing an integer to a function that accepts a void pointer Heikki Kallasjoki <see@end.of.message.invalid> - 2011-05-11 13:03 +0000
      Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-11 06:46 -0700
        Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-11 08:24 -0700
          Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-11 08:44 -0700
            Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-11 08:58 -0700
              Re: Passing an integer to a function that accepts a void pointer gazelle@shell.xmission.com (Kenny McCormack) - 2011-05-11 17:38 +0000
                Re: Passing an integer to a function that accepts a void pointer Kenneth Brody <kenbrody@spamcop.net> - 2011-05-11 14:57 -0400
                Re: Passing an integer to a function that accepts a void pointer Paul N <gw7rib@aol.com> - 2011-05-11 14:06 -0700
                Re: Passing an integer to a function that accepts a void pointer Michael Press <rubrum@pacbell.net> - 2011-05-12 13:59 -0700
                Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 14:12 -0700
                Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 15:27 -0700
                Re: Passing an integer to a function that accepts a void pointer Seebs <usenet-nospam@seebs.net> - 2011-05-12 22:37 +0000
                Re: Passing an integer to a function that accepts a void pointer Ian Collins <ian-news@hotmail.com> - 2011-05-13 10:41 +1200
                Re: Passing an integer to a function that accepts a void pointer Shao Miller <sha0.miller@gmail.com> - 2011-05-12 17:57 -0500
                Re: Passing an integer to a function that accepts a void pointer Ian Collins <ian-news@hotmail.com> - 2011-05-13 11:05 +1200
                Re: Passing an integer to a function that accepts a void pointer Seebs <usenet-nospam@seebs.net> - 2011-05-12 23:19 +0000
                Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 16:32 -0700
                Re: Passing an integer to a function that accepts a void pointer Shao Miller <sha0.miller@gmail.com> - 2011-05-12 19:13 -0500
                Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 18:18 -0700
                Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 16:18 -0700
                Re: Passing an integer to a function that accepts a void pointer Tobias Blass <tobiasblass@gmx.net> - 2011-05-13 08:24 +0000
                Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-13 01:33 -0700
                Re: Passing an integer to a function that accepts a void pointer Seebs <usenet-nospam@seebs.net> - 2011-05-13 08:36 +0000
                Re: Passing an integer to a function that accepts a void pointer "madamemandm@yahoo.com" <madamemandm@yahoo.com> - 2011-05-13 07:08 -0700
                Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 15:59 -0700
            Re: Passing an integer to a function that accepts a void pointer Seebs <usenet-nospam@seebs.net> - 2011-05-11 21:46 +0000
              Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 00:56 -0700
                Re: Passing an integer to a function that accepts a void pointer Ian Collins <ian-news@hotmail.com> - 2011-05-12 20:06 +1200
                Re: Passing an integer to a function that accepts a void pointer Heikki Kallasjoki <see@end.of.message.invalid> - 2011-05-12 08:59 +0000
                Re: Passing an integer to a function that accepts a void pointer Ian Collins <ian-news@hotmail.com> - 2011-05-13 10:39 +1200
        Re: Passing an integer to a function that accepts a void pointer Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-12 06:51 -0400
          Re: Passing an integer to a function that accepts a void pointer Columbus sailed the ocean China Blue <chine.bleu@yahoo.com> - 2011-05-12 04:08 -0700
            Re: Passing an integer to a function that accepts a void pointer Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-12 07:33 -0400
            Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 07:58 -0700
              Re: Passing an integer to a function that accepts a void pointer gazelle@shell.xmission.com (Kenny McCormack) - 2011-05-12 15:23 +0000
              Re: Passing an integer to a function that accepts a void pointer Shao Miller <sha0.miller@gmail.com> - 2011-05-12 13:36 -0400
                Re: Passing an integer to a function that accepts a void pointer Keith Thompson <kst-u@mib.org> - 2011-05-12 12:03 -0700
            Re: Passing an integer to a function that accepts a void pointer Seebs <usenet-nospam@seebs.net> - 2011-05-12 15:57 +0000
          Re: Passing an integer to a function that accepts a void pointer Michael Press <rubrum@pacbell.net> - 2011-05-12 14:14 -0700
            Re: Passing an integer to a function that accepts a void pointer Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-12 22:20 -0400
              Re: Passing an integer to a function that accepts a void pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-05-14 02:39 +0100
  Re: Passing an integer to a function that accepts a void pointer Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-05-11 07:37 -0400
  Re: Passing an integer to a function that accepts a void pointer James Kuyper <jameskuyper@verizon.net> - 2011-05-11 09:42 -0400
  Re: Passing an integer to a function that accepts a void pointer Datesfat Chicks <datesfat.chicks@gmail.com> - 2011-05-11 11:53 -0400
    Re: Passing an integer to a function that accepts a void pointer Fred <fred.l.kleinschmidt@boeing.com> - 2011-05-11 10:44 -0700
      Re: Passing an integer to a function that accepts a void pointer Datesfat Chicks <datesfat.chicks@gmail.com> - 2011-05-12 07:58 -0400
    Re: Passing an integer to a function that accepts a void pointer Dr Nick <3-nospam@temporary-address.org.uk> - 2011-05-11 21:27 +0100

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