Re: question about nullptr

From	Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: question about nullptr
Date	2024-07-06 16:31 -0700
Organization	None to speak of
Message-ID	<87wmlyt7vj.fsf@nosuchdomain.example.com> (permalink)
References	<v6bavg$3pu5i$1@dont-email.me> <20240706054641.175@kylheku.com> <v6bfi1$3qn4u$1@dont-email.me> <l9ciO.7$cr5e.2@fx05.iad> <v6c1su$3tl33$1@dont-email.me>

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bart <bc@freeuk.com> writes:
> On 06/07/2024 15:04, Scott Lurndal wrote:
[...]
>> Whereas I spent 6 years programming on an architecture[*] where a
>> null pointer was represented in hardware by the value 0xc0eeeeee.  I always
>> use the NULL macro in both C and C++ code.
>
> You can ignore that requirement and just use all-bits-zero (in memory,
> not just in C source code). After all, the only thing you might want
> hardware support for is trapping a dereference of a NULL value.

You write this in response to someone saying they've used a system
where a null pointer is *not* all-bits-zero.

The vast majority of systems do represent a null pointer as
all-bits-zero, and you can usually get away with assuming that.
There are even some cases where it might be worthwhile, for example
if you need to memset chunks of memory that contain pointers and
aren't concerned about 100% portability (or if you're using your
own langauge).

Or you can use the language in a way that works correctly regardless
of now null pointers are represented.  That's what I do.

[...]

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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question about nullptr Thiago Adams <thiago.adams@gmail.com> - 2024-07-06 08:49 -0300
  Re: question about nullptr Bonita Montero <Bonita.Montero@gmail.com> - 2024-07-06 14:13 +0200
  Re: question about nullptr John McCue <jmccue@neutron.jmcunx.com> - 2024-07-06 12:33 +0000
  Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-06 12:54 +0000
    Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-06 15:07 +0200
      Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-06 14:04 +0000
        Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-06 16:42 +0200
          Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-06 16:45 +0200
        Re: question about nullptr Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-07-06 10:50 -0700
          Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-06 23:04 +0000
            Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-06 20:06 -0700
        Re: question about nullptr bart <bc@freeuk.com> - 2024-07-06 19:20 +0100
          Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-06 23:09 +0000
          Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-06 16:31 -0700
        Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-06 13:23 -0700
          Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-06 13:28 -0700
            Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-07 08:01 +0000
              Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-08 22:08 -0700
          Re: question about nullptr Richard Damon <richard@damon-family.org> - 2024-07-06 17:04 -0400
            Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-06 23:10 +0000
          Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-06 23:03 +0000
          Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-06 21:44 -0400
            Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-06 19:29 -0700
              Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-07 12:53 -0700
          Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-07 08:03 +0000
        Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-06 23:14 +0100
          Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-06 23:13 +0000
            Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-06 20:10 -0700
            Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-07 08:46 +0000
            Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-07 19:59 +0100
              Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-07 19:40 +0000
                Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-07 15:17 -0700
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-08 20:11 +0200
                Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-08 13:32 -0700
                Re: question about nullptr Michael S <already5chosen@yahoo.com> - 2024-07-08 22:28 +0300
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-08 15:23 -0700
                Re: question about nullptr Michael S <already5chosen@yahoo.com> - 2024-07-09 10:48 +0300
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-09 04:32 -0700
                Re: question about nullptr Thiago Adams <thiago.adams@gmail.com> - 2024-07-09 09:10 -0300
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-09 07:52 -0700
                Re: question about nullptr Thiago Adams <thiago.adams@gmail.com> - 2024-07-09 13:16 -0300
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-09 14:22 -0700
                Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-09 22:25 +0000
                Re: question about nullptr Thiago Adams <thiago.adams@gmail.com> - 2024-07-10 08:50 -0300
                Re: question about nullptr Michael S <already5chosen@yahoo.com> - 2024-07-09 15:50 +0300
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-09 07:50 -0700
                Re: question about nullptr David Brown <david.brown@hesbynett.no> - 2024-07-09 18:19 +0200
                Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-09 02:49 +0000
                Re: question about nullptr Michael S <already5chosen@yahoo.com> - 2024-07-09 11:00 +0300
                Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-09 08:21 +0000
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-09 03:57 -0700
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-08 20:17 -0700
                Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-08 21:01 -0700
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-08 22:06 -0700
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-10 07:51 -0700
                Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-10 14:23 -0700
                Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-10 18:50 -0400
                Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-08 14:09 +0000
                Re: question about nullptr Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-07-08 21:45 -0700
                Re: question about nullptr Andrey Tarasevich <andreytarasevich@hotmail.com> - 2024-07-08 21:49 -0700
                Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-11 02:42 +0000
                Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-08 22:58 -0700
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-10 07:36 -0700
                Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-10 14:15 -0700
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-08 20:07 +0200
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-08 23:55 +0100
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-10 17:28 +0200
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-11 00:25 +0100
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-12 14:08 +0200
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-13 00:59 +0100
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-13 04:01 +0200
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-15 00:00 +0100
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-13 04:18 +0200
                Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-17 09:26 -0700
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-08 12:29 +0200
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-08 17:23 +0100
                Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-08 11:03 -0400
                Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-09 02:45 +0000
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-08 11:08 +0200
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-08 11:18 +0100
                Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-09 02:32 +0000
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-08 22:02 -0700
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-09 10:21 +0100
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-10 17:32 -0700
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-11 02:12 +0100
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-10 18:41 -0700
                Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-11 02:38 +0000
                Re: question about nullptr Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-07-12 14:11 +0200
                Re: question about nullptr Richard Damon <richard@damon-family.org> - 2024-07-08 07:18 -0400
                Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-08 07:19 +0000
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-08 00:42 +0100
          Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-06 20:36 -0700
      Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-06 22:11 +0000
    Re: question about nullptr bart <bc@freeuk.com> - 2024-07-06 14:51 +0100
      Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-07 04:55 +0000
        Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-07 00:04 -0700
        Re: question about nullptr bart <bc@freeuk.com> - 2024-07-07 18:40 +0100
    Re: question about nullptr Richard Harnden <richard.nospam@gmail.invalid> - 2024-07-12 14:19 +0100
      Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-12 21:52 +0000
        Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-12 22:27 +0000
          Re: question about nullptr Kaz Kylheku <643-408-1753@kylheku.com> - 2024-07-12 23:28 +0000
            Re: question about nullptr scott@slp53.sl.home (Scott Lurndal) - 2024-07-13 00:10 +0000
              Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-12 20:28 -0400
              Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-12 17:30 -0700
      Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-07-13 17:21 -0700
      Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-15 22:51 +0000
        Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-15 16:32 -0700
        Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-15 19:49 -0400
          Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-07-15 18:22 -0700
  Re: question about nullptr Richard Damon <richard@damon-family.org> - 2024-07-06 10:39 -0400
    Re: question about nullptr David Brown <david.brown@hesbynett.no> - 2024-07-06 18:57 +0200
      Re: question about nullptr Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-07-07 08:00 +0000
        Re: question about nullptr David Brown <david.brown@hesbynett.no> - 2024-07-07 12:07 +0200
      Re: question about nullptr Thiago Adams <thiago.adams@gmail.com> - 2024-07-07 08:40 -0300
      Re: question about nullptr Richard Harnden <richard.nospam@gmail.invalid> - 2024-07-09 06:42 +0100
        Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-08 23:17 -0700
          Re: question about nullptr Richard Harnden <richard.nospam@gmail.invalid> - 2024-07-09 08:02 +0100
            Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-09 00:12 -0700
              Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-09 11:14 +0100
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-09 13:24 -0700
                Re: question about nullptr "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-07-09 13:28 -0700
                Re: question about nullptr Ben Bacarisse <ben@bsb.me.uk> - 2024-07-10 14:27 +0100
                Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-07-10 11:09 -0400

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