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Re: What is the data structure of a NULL?

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c++
Subject Re: What is the data structure of a NULL?
Date 2019-12-30 17:27 +0100
Organization A noiseless patient Spider
Message-ID <qud8ht$c46$1@dont-email.me> (permalink)
References (6 earlier) <slrnr0h0v1.to9.nedlatham@woden.valhalla.oz> <qubjcd$glg$1@dont-email.me> <slrnr0isv8.uul.nedlatham@woden.valhalla.oz> <87r20mpaxz.fsf@nosuchdomain.example.com> <slrnr0jjq0.vao.nedlatham@woden.valhalla.oz>

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On 30/12/2019 11:19, Ned Latham wrote:
> Keith Thompson wrote:
>> Ned Latham writes:
>>> James Kuyper wrote:
>>>> Ned Latham wrote:
>>>>> Keith Thompson wrote:
>>>>>>
>>>>>> You indicated that it's useful to know how a null pointer is
>>>>>> represented.  How is it useful?  Most of the time, the representation
>>>>>> doesn't matter.
>>>>>
>>>>> Knowing it's useful in that it enables me to use it.
>>>>
>>>> Can you give an example of code involving a null pointer that you could
>>>> not have used if you had not known how null pointers are represented? I
>>>> write code that deals correctly with null pointers all the time, and to
>>>> the best of my knowledge, not a single line of code I've ever written
>>>> would need a re-write if ported to a system which uses a different
>>>> representation for null pointers.
>>>
>>> http://www.users.on.net/~nedlatham/Software/mclib/Documents/sourcecode.html
>>>
>>> Check AVLC and ListC, also read
>>> http://www.users.on.net/~nedlatham/Software/mclib/Documents/mclists.html
>>
>> Can you give a *succinct* example?  I'm not going to spend the time it
>> would take to read that.
> 
> What you've got is working code and documentation describing it. The AVLC
> Specification document details three funcions that take void* parameters
> and also return void*, Extract(), Find(), Insert().
> 

Even though you apparently have no intention of answering Keith's
questions sensibly, could you at least say why you think a function
returning void* is dependent on the representation of null pointers?

Your documentation says your code relies on void* being the same size as
int.  I didn't see anything in the code that actually depends on that
(but I have not gone through it in detail) - but that bears no direct
relationship on the representation of null pointer constants.

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Thread

What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-27 13:24 -0800
  Re: What is the data structure of a NULL? Ian Collins <ian-news@hotmail.com> - 2019-12-28 10:36 +1300
    Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-27 13:55 -0800
      Re: What is the data structure of a NULL? Bo Persson <bo@bo-persson.se> - 2019-12-28 11:28 +0100
    Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-27 20:50 -0500
      Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-28 17:14 -0800
      Re: What is the data structure of a NULL? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2020-01-10 20:56 -0800
  Re: What is the data structure of a NULL? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-12-27 22:42 +0100
    Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-27 13:55 -0800
      Re: What is the data structure of a NULL? "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> - 2019-12-27 23:10 +0100
      Re: What is the data structure of a NULL? Öö Tiib <ootiib@hot.ee> - 2019-12-27 14:15 -0800
        Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-27 14:24 -0800
          Re: What is the data structure of a NULL? Öö Tiib <ootiib@hot.ee> - 2019-12-27 14:41 -0800
          Re: What is the data structure of a NULL? Manfred <noname@add.invalid> - 2019-12-28 20:11 +0100
            Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-28 17:16 -0800
              Re: What is the data structure of a NULL? Manfred <noname@invalid.add> - 2019-12-29 17:52 +0100
                Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-29 12:21 -0800
      Re: What is the data structure of a NULL? Bart <bc@freeuk.com> - 2019-12-28 01:46 +0000
        Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-28 17:17 -0800
          Re: What is the data structure of a NULL? Bart <bc@freeuk.com> - 2019-12-29 01:42 +0000
            Re: What is the data structure of a NULL? T <T@invalid.invalid> - 2019-12-28 18:39 -0800
  Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-28 02:14 -0800
    Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-28 08:33 -0600
      Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-28 13:22 -0800
        Re: What is the data structure of a NULL? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-12-28 16:02 -0800
          Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-28 22:37 -0600
        Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-28 22:37 -0600
          Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-28 21:12 -0800
            Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-29 04:45 -0600
              Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-29 13:31 -0800
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-29 21:34 -0600
                Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-29 22:48 -0800
              Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-29 20:20 -0500
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-29 21:50 -0600
                Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-29 22:46 -0800
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2019-12-30 10:25 +0100
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-30 05:20 -0600
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2019-12-30 17:24 +0100
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-30 17:22 -0600
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2019-12-31 13:57 +0100
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-31 07:33 -0600
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2019-12-31 15:45 +0100
                Re: What is the data structure of a NULL? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-12-30 18:16 +0000
                Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-30 10:45 -0800
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-30 17:29 -0600
                Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-30 21:48 -0800
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-30 04:19 -0600
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2019-12-30 17:27 +0100
                Re: What is the data structure of a NULL? Öö Tiib <ootiib@hot.ee> - 2019-12-30 03:25 -0800
                Re: What is the data structure of a NULL? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-12-31 21:54 +0000
                Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-30 06:03 -0800
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-30 17:01 -0600
                Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-30 21:42 -0500
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-31 06:03 -0600
                Re: What is the data structure of a NULL? Öö Tiib <ootiib@hot.ee> - 2019-12-31 06:17 -0800
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-31 10:46 -0600
                Re: What is the data structure of a NULL? Melzzzzz <Melzzzzz@zzzzz.com> - 2019-12-31 16:57 +0000
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2019-12-31 18:15 +0100
                Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-31 11:20 -0800
                Re: What is the data structure of a NULL? David Brown <david.brown@hesbynett.no> - 2020-01-01 17:01 +0100
                Re: What is the data structure of a NULL? Ned Latham <nedlatham@woden.valhalla.oz> - 2019-12-31 11:21 -0600
                Re: What is the data structure of a NULL? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-12-31 21:37 +0000
                Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-31 15:21 -0800
                Re: What is the data structure of a NULL? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-12-31 17:26 +0000
                Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-31 23:30 -0500
                Re: What is the data structure of a NULL? Manfred <noname@add.invalid> - 2020-01-01 18:10 +0100
                Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-01-01 12:21 -0500
                Re: What is the data structure of a NULL? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-12-31 15:20 +0000
                Re: What is the data structure of a NULL? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2019-12-31 11:11 -0800
                Re: What is the data structure of a NULL? Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2019-12-31 19:47 +0000
                Re: What is the data structure of a NULL? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-12-31 10:27 -0800

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