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Re: AVL tree insertion - programming exercise

From cross@spitfire.i.gajendra.net (Dan Cross)
Newsgroups comp.lang.c
Subject Re: AVL tree insertion - programming exercise
Date 2026-10-13 21:17 +0000
Organization PANIX Public Access Internet and UNIX, NYC
Message-ID <11am74c$54g$1@reader2.panix.com> (permalink)
References <86ece2kppv.fsf@linuxsc.com> <11al4mu$fqtl$1@kst.eternal-september.org> <11ali2e$pi$1@reader2.panix.com> <86v775h9o2.fsf@linuxsc.com>

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In article <86v775h9o2.fsf@linuxsc.com>,
Tim Rentsch  <tr.17687@z991.linuxsc.com> wrote:
>cross@spitfire.i.gajendra.net (Dan Cross) writes:
>
>> In article <11al4mu$fqtl$1@kst.eternal-september.org>,
>> Keith Thompson  <Keith.S.Thompson+u@gmail.com> wrote:
>>
>>> David Brown <david.brown@hesbynett.no> writes:
>>>
>>>> On 13/10/2026 10:38, chine.bleu wrote:
>>>>
>>>>> Tim Rentsch wrote:
>>>>>
>>>>>> sons[2] array.  These links are basically pointers, but held
>>>>>> as uintptr_t so they can take one of the bits to mean "tall",
>>>>>> which means taller than the other subtree of the node.  The
>>>>>> tree structure should maintain an invariant that at most one
>>>>>
>>>>> Memory is cheap.
>>>>
>>>> Not any more!
>>>>
>>>>> Do not encode tags into low bits of an address unless you really
>>>>> know what your doing.
>>>>
>>>> Agreed, as a principle.
>>>>
>>>>> As a precaution check the return address of malloc
>>>>>      p = malloc(m);
>>>>>      if ((uintptr_t)p)&1!=0) abort();
>>>>
>>>> malloc always returns an address with suitable alignment for any
>>>> fundamental alignment on the target.
>>
>> I don't think this is true anymore, as of C23.  Here's the
>> relevant text from n3220, sec 7.24.3, describing the return
>> value from `malloc` et al:
>>
>> |The pointer returned if the allocation succeeds is suitably
>> |aligned so that it may be assigned to a pointer to any type of
>> |object with a fundamental alignment requirement and size less
>> |than or equal to the size requested.
>>
>> This sentence is somewhat ambiguous because it's unclear whether
>> the "less than or equal to the size requested" criteria applies
>> to both the pointer type's size _and_ fundamental alignment
>> requirement, or _just_ the size, [...]
>
>It's poorly constructed but in English it has only one
>grammatical parse.

Nope.  Not even close.

	- Dan C.

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AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-06 23:08 -0700
  Re: AVL tree insertion - programming exercise fir <profesor.fir@gmail.com> - 2026-10-07 15:25 +0200
    Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-07 12:13 -0700
      Re: AVL tree insertion - programming exercise fir <profesor.fir@gmail.com> - 2026-10-07 21:28 +0200
        Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-08 05:31 -0700
          Re: AVL tree insertion - programming exercise fir <profesor.fir@gmail.com> - 2026-10-09 11:12 +0200
            Re: AVL tree insertion - programming exercise fir <profesor.fir@gmail.com> - 2026-10-09 11:12 +0200
      Re: AVL tree insertion - programming exercise BGB <cr88192@gmail.com> - 2026-10-07 20:10 -0500
        Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-08 05:56 -0700
          Re: AVL tree insertion - programming exercise BGB <cr88192@gmail.com> - 2026-10-08 15:09 -0500
            Re: AVL tree insertion - programming exercise fir <profesor.fir@gmail.com> - 2026-10-08 22:56 +0200
              Re: AVL tree insertion - programming exercise BGB <cr88192@gmail.com> - 2026-10-08 17:29 -0500
                Re: AVL tree insertion - programming exercise fir <profesor.fir@gmail.com> - 2026-10-09 09:56 +0200
            Re: AVL tree insertion - programming exercise Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-09 01:39 +0200
              Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-09 00:03 -0700
            Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-08 23:53 -0700
              Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-09 10:34 +0200
                Re: AVL tree insertion - programming exercise Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-09 12:27 +0200
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-09 12:59 +0200
                Re: AVL tree insertion - programming exercise bart <bc@freeuk.com> - 2026-10-09 11:43 +0100
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-09 13:20 +0200
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-09 12:38 +0000
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-09 16:05 +0200
                Re: AVL tree insertion - programming exercise Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-09 17:54 +0200
                Re: AVL tree insertion - programming exercise Johann 'Myrkraverk' Oskarsson <johann@myrkraverk.invalid> - 2026-10-10 10:38 +0800
                Re: AVL tree insertion - programming exercise ram@zedat.fu-berlin.de (Stefan Ram) - 2026-10-10 03:12 +0000
                Re: AVL tree insertion - programming exercise Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-10-10 04:44 +0000
                Re: AVL tree insertion - programming exercise "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-10 14:12 -0700
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-09 19:48 +0000
                Re: AVL tree insertion - programming exercise scott@slp53.sl.home (Scott Lurndal) - 2026-10-09 23:18 +0000
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-10 15:27 +0200
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-12 18:26 +0000
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-12 21:17 +0200
                Re: AVL tree insertion - programming exercise Michael S <already5chosen@yahoo.com> - 2026-10-09 17:47 +0300
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-09 16:48 +0000
                Re: AVL tree insertion - programming exercise Michael S <already5chosen@yahoo.com> - 2026-10-10 19:08 +0300
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-10 18:29 +0200
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-10 17:44 +0000
                Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-10 23:22 +0200
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-10 17:43 +0000
                Re: AVL tree insertion - programming exercise Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-10 20:35 +0200
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-10 19:36 +0000
                Re: AVL tree insertion - programming exercise Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-10 22:08 +0200
                Re: AVL tree insertion - programming exercise Michael S <already5chosen@yahoo.com> - 2026-10-10 23:21 +0300
                Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-10 20:55 +0000
                Re: AVL tree insertion - programming exercise scott@slp53.sl.home (Scott Lurndal) - 2026-10-10 20:22 +0000
                Re: AVL tree insertion - programming exercise Michael S <already5chosen@yahoo.com> - 2026-10-10 23:32 +0300
                Re: AVL tree insertion - programming exercise scott@slp53.sl.home (Scott Lurndal) - 2026-10-11 15:24 +0000
  Re: AVL tree insertion - programming exercise Bonita Montero <Bonita.Montero@gmail.com> - 2026-10-10 19:40 +0200
  Re: AVL tree insertion - programming exercise Andrey Tarasevich <noone@noone.net> - 2026-10-10 12:39 -0700
    Re: AVL tree insertion - programming exercise Michael S <already5chosen@yahoo.com> - 2026-10-10 23:00 +0300
    Re: AVL tree insertion - programming exercise Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2026-10-10 22:28 +0200
    Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-10 19:02 -0700
  Re: AVL tree insertion - programming exercise "chine.bleu" <chine.bleu@yahoo.com> - 2026-10-13 01:38 -0700
    Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-13 11:42 +0200
      Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-13 10:55 +0000
      Re: AVL tree insertion - programming exercise Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-13 04:29 -0700
        Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-13 14:01 +0200
          Re: AVL tree insertion - programming exercise Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2026-10-13 05:09 -0700
          Re: AVL tree insertion - programming exercise antispam@fricas.org (Waldek Hebisch) - 2026-10-13 19:01 +0000
        Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-13 15:17 +0000
          Re: AVL tree insertion - programming exercise David Brown <david.brown@hesbynett.no> - 2026-10-13 17:39 +0200
          Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-13 09:01 -0700
            Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-13 21:17 +0000
          Re: AVL tree insertion - programming exercise scott@slp53.sl.home (Scott Lurndal) - 2026-10-13 17:15 +0000
            Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-13 21:30 +0000
      Re: AVL tree insertion - programming exercise "chine.bleu" <chine.bleu@yahoo.com> - 2026-10-13 08:19 -0700
      Re: AVL tree insertion - programming exercise "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-10-13 13:16 -0700
        Re: AVL tree insertion - programming exercise Michael S <already5chosen@yahoo.com> - 2026-10-13 23:28 +0300
    Re: AVL tree insertion - programming exercise James Kuyper <jameskuyper@alumni.caltech.edu> - 2026-10-13 06:20 -0400
      Re: AVL tree insertion - programming exercise cross@spitfire.i.gajendra.net (Dan Cross) - 2026-10-13 14:34 +0000
    Re: AVL tree insertion - programming exercise Tim Rentsch <tr.17687@z991.linuxsc.com> - 2026-10-13 03:52 -0700

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