Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Ben Bacarisse <ben@bsb.me.uk>
Newsgroups: comp.lang.c
Subject: Re: question about nullptr
Date: Sun, 07 Jul 2024 19:59:25 +0100
Organization: A noiseless patient Spider
Lines: 55
Message-ID: <87plrpt4du.fsf@bsb.me.uk>
References: <v6bavg$3pu5i$1@dont-email.me> <20240706054641.175@kylheku.com>
	<v6bfi1$3qn4u$1@dont-email.me> <l9ciO.7$cr5e.2@fx05.iad>
	<877cdyuq0f.fsf@bsb.me.uk> <2ckiO.19403$7Ej.4487@fx46.iad>
MIME-Version: 1.0
Content-Type: text/plain
Injection-Date: Sun, 07 Jul 2024 20:59:26 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="213b794f72069ae5495c2f80bfa9f0a2";
	logging-data="480838"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+M93Bbfh4gwjBT0aCV5YCJ+BU9q3m1H1I="
User-Agent: Gnus/5.13 (Gnus v5.13)
Cancel-Lock: sha1:mpTN0j76MNd3UpDVE/XayaAvsHs=
	sha1:yc8/p++Uty1QcktOp8XkS8it/AM=
X-BSB-Auth: 1.4288a306a33759b0342b.20240707195925BST.87plrpt4du.fsf@bsb.me.uk
Bytes: 3460

scott@slp53.sl.home (Scott Lurndal) writes:

> Ben Bacarisse <ben@bsb.me.uk> writes:
>>scott@slp53.sl.home (Scott Lurndal) writes:
>>
>>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>>>>On 06.07.2024 14:54, Kaz Kylheku wrote:
>>>>> On 2024-07-06, Thiago Adams <thiago.adams@gmail.com> wrote:
>>>>>> If you were creating C code today and could use a C23 compiler, would 
>>>>>> you use nullptr instead of NULL?
>>>>> 
>>>>> In greenfield projects under my dictatorship, I use 0, as in:
>>>>> 
>>>>>    char *p = 0;
>>>>> 
>>>>> I was still 20 something when I (easily) wrapped my head around the 0
>>>>> null pointer constant, and have not had any problems with it.
>>>>> Once I learned the standard-defined truth about null pointer constants,
>>>>> and their relationship to the NULL macro, I dropped NULL like a hot
>>>>> potato, and didn't look back (except when working in code bases that use
>>>>> NULL).
>>>>
>>>>We also used 0 as "universal" pointer value regularly without
>>>>problems.
>>
>>I also like to use 0, but I'm not sure I could say exactly why.  Maybe
>>because of pre-C exposure (B and BCPL).
>>
>>> 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.
>>
>>I'm sure you know (but maybe some other readers might not) that that
>>does not stop one using 0 in C source code.  Whatever a null pointer
>>"really" is on some hardware, 0 must work in C, including in comparisons
>>with == and !=.  You can have
>
> Yes.  However, I consider that ambiguous, I prefer to be explicit and
> use NULL or nullptr.

In what sense is using 0 ambiguous?  I can't see it.

Ambiguous and explicit are not opposites, so many you did not mean to
say that 0 is ambiguous.  Its use does require the reader to know the
role played by zero integer constant expressions in C.

But then NULL might be defined to be 0.  It /looks/ more like a pointer
but there's lots of code that erroneously assumes that it is, presumably
because of that deceptive look.  (nullptr is another matter.)

Do you always cast NULL to a pointer in those (admittedly rare) cases
when one needs to?  I think it's easier to remember to do that with 0.

-- 
Ben.