Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.c > #167012
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: New features added into C23 standard |
| Date | 2022-07-31 16:48 -0700 |
| Organization | None to speak of |
| Message-ID | <87edy0x2r9.fsf@nosuchdomain.example.com> (permalink) |
| References | (4 earlier) <40f5c874-ba25-4020-98a0-b6ce01b38dban@googlegroups.com> <tc3903$3rs12$1@dont-email.me> <87mtcqwaes.fsf@nosuchdomain.example.com> <f4iFK.137308$%i2.27973@fx48.iad> <20220730162133.56@kylheku.com> |
Kaz Kylheku <480-992-1380@kylheku.com> writes:
> On 2022-07-30, Richard Damon <Richard@Damon-Family.org> wrote:
>> On 7/30/22 5:36 PM, Keith Thompson wrote:
>>> David Brown <david.brown@hesbynett.no> writes:
>>> [...]
>>>> The key problem with null pointers in C code is that "0" is a null
>>>> pointer as well as an integer constant. So it's easy to mix up these
>>>> very different purposes when writing or reading code. (Let's be
>>>> honest here - most null pointers in real code are written "0", not
>>>> "NULL".)
>>> [...]
>>>
>>> That doesn't match my experience at all. In C, I always use NULL for
>>> null pointer constants.
>>>
>>> (I seem to recall that Stroustrup advocated using 0 as a null pointer
>>> constant before nullptr was introduced in C++11.)
>>
>> C++ had the problem that (void *)0 didn't work for NULL as it doesn't
>> convert to other pointer types, while a constant expression 0 does.
>
> That makes no sense, though. A constant expression 1 does not convert
> to pointer types in C++; the zero-valued expression only converts
> because there is a hack in the language: that of the expression doubling
> as a null pointer constant, just like in C.
>
> Exactly the same hack can be implemented to allow (void *) 0 to
> convert in situations where (void *) 1 won't.
>
> C++ made a mess of the null pointer area; now the crap is seeping into C.
I disagree.
C++ added nullptr in the 2011 standard. It's a keyword that
is a null pointer constant and *only* a null pointer constant,
not requiring any special case rules about converting integer
expressions.
In addition, C++ narrowed the definition of "null pointer
constant", so it can be an integer literal (not a more general
integer constant expression, and not cast to void*) or a prvalue
of type std::nullptr_t.
C++ still defines NULL as an implementation-defined null pointer
constant in <cstddef>. That's necessary to avoid breaking existing
code.
But if you ignore all that and just use nullptr when you want a
null pointer constant, the result is IMHO much cleaner. I'm glad
to see C adopting a similar solution.
--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
New features added into C23 standard Thiago Adams <thiago.adams@gmail.com> - 2022-07-22 12:32 -0700
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-22 23:15 +0100
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-23 01:31 -0700
Re: New features added into C23 standard gazelle@shell.xmission.com (Kenny McCormack) - 2022-07-23 10:10 +0000
Re: New features added into C23 standard Thiago Adams <thiago.adams@gmail.com> - 2022-07-25 13:49 -0700
Re: New features added into C23 standard Thiago Adams <thiago.adams@gmail.com> - 2022-07-25 13:57 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-25 14:50 -0700
Re: New features added into C23 standard Thiago Adams <thiago.adams@gmail.com> - 2022-07-25 15:51 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-25 18:04 -0700
Re: New features added into C23 standard Thiago Adams <thiago.adams@gmail.com> - 2022-07-25 19:23 -0700
Re: New features added into C23 standard Opus <ifonly@youknew.org> - 2022-07-26 05:13 +0200
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-25 23:36 -0400
Re: New features added into C23 standard Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-07-25 21:52 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-26 11:44 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-26 11:39 -0700
Re: New features added into C23 standard David Brown <david.brown@hesbynett.no> - 2022-07-30 14:42 +0200
Re: New features added into C23 standard scott@slp53.sl.home (Scott Lurndal) - 2022-07-30 15:18 +0000
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-30 09:13 -0700
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-30 17:31 +0100
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-30 16:46 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-30 14:36 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-30 18:15 -0400
Re: New features added into C23 standard Kaz Kylheku <480-992-1380@kylheku.com> - 2022-07-30 23:28 +0000
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-31 16:48 -0700
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-31 22:42 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-31 23:25 -0700
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-08-01 00:10 -0700
Re: New features added into C23 standard David Brown <david.brown@hesbynett.no> - 2022-08-01 09:55 +0200
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-08-01 20:17 +0100
Re: New features added into C23 standard Kaz Kylheku <480-992-1380@kylheku.com> - 2022-07-30 23:21 +0000
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-25 22:59 -0700
Re: New features added into C23 standard Öö Tiib <ootiib@hot.ee> - 2022-07-26 00:48 -0700
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-26 02:08 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-26 06:59 -0400
Re: New features added into C23 standard Öö Tiib <ootiib@hot.ee> - 2022-07-26 04:02 -0700
Re: New features added into C23 standard Vir Campestris <vir.campestris@invalid.invalid> - 2022-07-29 21:18 +0100
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-29 16:55 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-26 11:51 -0700
Re: New features added into C23 standard David Brown <david.brown@hesbynett.no> - 2022-07-31 11:12 +0200
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-31 07:40 -0400
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-31 17:40 +0100
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-31 12:56 -0400
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-31 19:28 +0100
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-31 14:52 -0400
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-31 21:35 +0100
Re: New features added into C23 standard Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-08-15 23:24 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-31 16:57 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-31 16:55 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-31 20:09 -0400
Re: New features added into C23 standard Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-08-15 22:52 -0700
Re: New features added into C23 standard David Brown <david.brown@hesbynett.no> - 2022-08-16 09:21 +0200
Re: New features added into C23 standard Philipp Klaus Krause <pkk@spth.de> - 2022-08-16 09:32 +0200
Re: New features added into C23 standard David Brown <david.brown@hesbynett.no> - 2022-08-16 11:06 +0200
Re: New features added into C23 standard Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-08-15 23:17 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-08-17 20:11 -0400
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-08-17 20:08 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-08-17 23:19 -0400
Re: New features added into C23 standard Kaz Kylheku <480-992-1380@kylheku.com> - 2022-08-18 07:03 +0000
Re: New features added into C23 standard Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-08-23 09:43 -0700
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-08-23 11:02 -0700
Re: New features added into C23 standard Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-08-23 13:40 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-26 07:04 -0400
Re: New features added into C23 standard Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-26 05:24 -0700
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-26 22:30 -0400
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-29 00:02 +0100
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-28 21:20 -0400
Re: New features added into C23 standard William Ahern <william@25thandClement.com> - 2022-07-28 19:36 -0700
Re: New features added into C23 standard scott@slp53.sl.home (Scott Lurndal) - 2022-07-29 16:39 +0000
Re: New features added into C23 standard Richard Damon <Richard@Damon-Family.org> - 2022-07-29 18:55 -0400
Re: New features added into C23 standard Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-29 15:17 +0100
Re: New features added into C23 standard scott@slp53.sl.home (Scott Lurndal) - 2022-07-26 13:27 +0000
Re: New features added into C23 standard Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-26 11:47 -0700
Re: New features added into C23 standard Kaz Kylheku <480-992-1380@kylheku.com> - 2022-07-26 20:27 +0000
Re: New features added into C23 standard Philipp Klaus Krause <pkk@spth.de> - 2022-08-16 08:42 +0200
Re: New features added into C23 standard Bonita Montero <Bonita.Montero@gmail.com> - 2022-07-26 05:37 +0200
Re: New features added into C23 standard Lynn McGuire <lynnmcguire5@gmail.com> - 2022-07-28 16:47 -0500
Re: New features added into C23 standard Bonita Montero <Bonita.Montero@gmail.com> - 2022-07-29 07:14 +0200
Re: New features added into C23 standard Vir Campestris <vir.campestris@invalid.invalid> - 2022-07-29 21:21 +0100
Re: New features added into C23 standard Grant Mulholland <grantlmul@gmail.com> - 2022-08-13 22:21 -0700
Re: New features added into C23 standard Lynn McGuire <lynnmcguire5@gmail.com> - 2022-08-15 21:21 -0500
Re: New features added into C23 standard Bonita Montero <Bonita.Montero@gmail.com> - 2022-08-16 08:39 +0200
Re: New features added into C23 standard Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-08-15 22:54 -0700
Re: New features added into C23 standard Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-08-18 12:03 -0700
Re: New features added into C23 standard "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-08-18 12:56 -0700
Re: New features added into C23 standard William Ahern <william@25thandClement.com> - 2022-08-18 16:07 -0700
Re: New features added into C23 standard Thiago Adams <thiago.adams@gmail.com> - 2022-08-18 18:47 -0700
Re: New features added into C23 standard Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-08-18 20:23 -0700
csiph-web