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 14:34 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<11alfgs$t7q$1@reader2.panix.com> (permalink)
References	<86ece2kppv.fsf@linuxsc.com> <11akqm4$c6h9$1@dont-email.me> <11al0l0$eefv$1@dont-email.me>

Show all headers | View raw

In article <11al0l0$eefv$1@dont-email.me>,
James Kuyper  <jameskuyper@alumni.caltech.edu> wrote:
>On 13/10/2026 10:38, chine.bleu wrote:
>...> As a precaution check the return
>> address of malloc
>> 
>>      p = malloc(m);
>>      if ((uintptr_t)p)&1!=0) abort();
>
>Just to be pedantic, the standard doesn't guarantee that the expression
>you use will test what you want to test. Since there is a guarantee that
>malloc() returns a universally aligned memory, I think it's actually
>more likely that the test will fail than that malloc() will fail, though
>both probabilities are quite negligible, so it's hard to be sure.

The syntax and precedence errors aside, the test is clearly
meant to ensure that the low bit in the return from `malloc` is
clear, so that it can be repurposed for other things.  It should
likely be:

	p = malloc(m);
	if (p == NULL || ((uintptr_t)p & 1) != 0) abort();

	- Dan C.

Thread

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

csiph-web