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Groups > comp.lang.c > #387783
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: question about nullptr |
| Date | 2024-08-25 18:18 -0700 |
| Organization | None to speak of |
| Message-ID | <87wmk4dqu8.fsf@nosuchdomain.example.com> (permalink) |
| References | (8 earlier) <v6k6a3$1gsq2$3@dont-email.me> <v6k6ha$1gsq2$4@dont-email.me> <v6m87m$1v1rh$1@dont-email.me> <cj6ncj93220a0hmgj64itsrlmngfmur44h@4ax.com> <vagjcl$25csn$1@dont-email.me> |
James Kuyper <jameskuyper@alumni.caltech.edu> writes:
> On 8/25/24 16:56, dave_thompson_2@comcast.net wrote:
>> On Wed, 10 Jul 2024 11:09:41 -0400, James Kuyper
>> <jameskuyper@alumni.caltech.edu> wrote:
>>
>>> NULL is required to expand
>>> into a null pointer constant ... 0 and (void*)0 are the
>>> two most likely and common choices.
>>>
>> ((void*)0)
>>
>> Otherwise NULL["foo"] gives quite the wrong result
>
> Correct. Sorry.
A mostly meaningless price of trivia: In C17 and earlier, an excessively
literal reading of the standard implies that ((void*)0) is not a null
pointer constant. It says that a null pointer constant is "An integer
constant expression with the value 0, or such an expression cast to type
void *". It does not say that a parenthesized null pointer constant is
a null pointer constant. (And (void*)0 is a null pointer constant but
not a valid definition for NULL.)
C23 fixes this by updating the wording for parenthesized expressions.
C17: "A *parenthesized expression* is a primary expression. Its type and
value are identical to those of the unparenthesized expression. It is an
lvalue, a function designator, or a void expression if the
unparenthesized expression is, respectively, an lvalue, a function
designator, or a void expression."
C23: "A *parenthesized expression* is a primary expression. Its type,
value, and semantics are identical to those of the unparenthesized
expression."
This was surely the intent all along.
--
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 Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 17:42 -0700
Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-12 18:33 -0700
Re: question about nullptr Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 18:10 -0700
Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-12 18:44 -0700
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 Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-11 20:52 -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 dave_thompson_2@comcast.net - 2024-08-25 16:55 -0400
Re: question about nullptr Richard Damon <richard@damon-family.org> - 2024-08-25 17:09 -0400
Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-25 23:46 -0400
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
Re: question about nullptr dave_thompson_2@comcast.net - 2024-08-25 16:56 -0400
Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-25 20:48 -0400
Re: question about nullptr Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-25 18:18 -0700
Re: question about nullptr James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-25 23:45 -0400
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