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Re: Differences between C and C++

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From Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups comp.lang.c++
Subject Re: Differences between C and C++
Date Tue, 26 Jul 2022 11:59:21 -0700
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Muttley@dastardlyhq.com writes:
> On Tue, 26 Jul 2022 02:42:09 -0700 (PDT)
> =?UTF-8?B?w5bDtiBUaWli?= <ootiib@hot.ee> wrote:
>>On Tuesday, 26 July 2022 at 11:09:14 UTC+3, Mut...@dastardlyhq.com wrote:
>>> On Tue, 26 Jul 2022 08:00:25 -0000 (UTC) 
>>> Juha Nieminen <nos...@thanks.invalid> wrote: 
>>> >Mut...@dastardlyhq.com wrote: 
>>> >>>C++ doesn't have compound literals, but it has some other features (that 
>>> >>>C doesn't) that make `f((struct s){1})` valid, but in C++ it's not an 
>>> >>>lvalue, so `&(struct s){1}` is not valid. 
>>> >> 
>>> >> Certainly doesn't work with Clang though you'd think if the same compiler 
>>
>>> >> can do it in C mode it should do it in C++ mode if there are no side
>>effects 
>>> >> of doing so. 
>>> > 
>>> >If the C++ standard doesn't consider it valid, then the compiler shouldn't 
>>> >consider it valid (C++) either, even if it just so happens to be valid C.
>>> Is that specifically states its not valid or simply doesn't mention it. 
>>> 
>>> Most C++ compilers will compile some C constructs which are not technically 
>>> legal in C++ such as non consts pointing to string literals, variable length 
>>
>>> arrays and variadic macros.
>>
>>It is then clearly said in documentation of such compilers. Also most
>>compilers provide standard compliant mode (like -pedantic of gcc) that
>>issues warnings about extensions used in code (and standard mandates
>>nothing else). 
>
> And? Juha said:
>
> "If the C++ standard doesn't consider it valid, then the compiler shouldn't
>  consider it valid (C++) either"
>
> Clearly plenty of compilers do consider non standard C++ valid.

Plenty of C++ compilers accept non standard C++ *in certain modes*.

The C++ standard requires certain errors to be diagnosed.  A C++
compiler that fails to diagnose, for example, an attempt to use a VLA
is not a conforming compiler.

Most C++ compilers are non-conforming by default, quietly accepting
extensions that are incompatible with the standard.  All conforming C++
compilers provide a way to issue all required diagnostics.

-- 
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 */

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Thread

Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-25 13:14 +0000
  Re: Differences between C and C++ "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-07-25 16:18 +0200
  Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-07-25 18:47 +0300
    Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-07-25 19:49 +0300
      Re: Differences between C and C++ Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-25 19:38 +0100
  Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-25 08:51 -0700
  Re: Differences between C and C++ Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-25 17:14 +0100
    Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-25 16:19 +0000
      Re: Differences between C and C++ Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-25 19:28 +0100
      Re: Differences between C and C++ Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-25 12:21 -0700
        Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-26 07:54 +0000
          Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-26 08:00 +0000
            Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-26 08:09 +0000
              Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-26 02:42 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-26 15:29 +0000
                Re: Differences between C and C++ scott@slp53.sl.home (Scott Lurndal) - 2022-07-26 16:30 +0000
                Re: Differences between C and C++ Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-26 11:59 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-27 07:52 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-27 01:56 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-27 14:51 +0000
                Re: Differences between C and C++ Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-27 11:11 -0700
    Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-26 06:09 +0000
      Re: Differences between C and C++ Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-07-27 17:33 +0100
  Re: Differences between C and C++ Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2022-07-25 17:45 +0100
  Re: Differences between C and C++ Paul N <gw7rib@aol.com> - 2022-07-27 10:09 -0700
    Re: Differences between C and C++ Bo Persson <bo@bo-persson.se> - 2022-07-27 19:28 +0200
      Re: Differences between C and C++ Paul N <gw7rib@aol.com> - 2022-07-27 11:43 -0700
        Re: Differences between C and C++ David Brown <david.brown@hesbynett.no> - 2022-07-29 18:04 +0200
          Re: Differences between C and C++ Richard Damon <Richard@Damon-Family.org> - 2022-07-29 18:47 -0400
            Re: Differences between C and C++ David Brown <david.brown@hesbynett.no> - 2022-07-30 14:08 +0200
      Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-28 08:03 +0000
        Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-28 01:57 -0700
          Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-28 09:04 +0000
    Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-28 06:53 +0000
      Re: Differences between C and C++ Richard Damon <Richard@Damon-Family.org> - 2022-07-28 07:33 -0400
        Re: Differences between C and C++ Bo Persson <bo@bo-persson.se> - 2022-07-28 15:04 +0200
          Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-28 15:11 +0000
            Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-07-28 20:03 +0300
              Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-29 07:56 +0000
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-07-29 12:03 +0300
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-29 09:28 +0000
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-29 12:27 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-29 05:43 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-29 14:14 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-29 08:25 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-29 15:48 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-29 13:12 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-30 09:28 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-30 03:39 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-30 14:23 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-30 19:07 -0700
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-31 07:22 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-31 06:07 -0700
                Re: Differences between C and C++ muttley@dastardlyhq.com - 2022-07-31 16:36 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-08-01 01:12 -0700
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-29 22:47 +0000
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-30 03:48 -0700
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-07-29 05:16 -0700
                Re: Differences between C and C++ Manfred <noname@add.invalid> - 2022-07-30 02:14 +0200
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-07-31 14:39 +0000
                Re: Differences between C and C++ "Fred. Zwarts" <F.Zwarts@KVI.nl> - 2022-07-31 18:49 +0200
                Re: Differences between C and C++ Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-31 14:49 -0700
                Re: Differences between C and C++ Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-07-31 17:03 -0700
                Re: Differences between C and C++ Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-08-01 00:16 -0700
                Re: Differences between C and C++ Ike Naar <ike@sdf.org> - 2022-08-01 07:27 +0000
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-08-01 10:47 +0300
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-08-01 10:34 +0300
                Re: Differences between C and C++ Manfred <noname@add.invalid> - 2022-08-03 01:20 +0200
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-08-03 07:59 +0000
                Re: Differences between C and C++ Bo Persson <bo@bo-persson.se> - 2022-08-03 12:45 +0200
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-08-03 10:53 +0000
                Re: Differences between C and C++ Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-08-03 03:58 -0700
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-08-03 14:49 +0300
                Re: Differences between C and C++ Öö Tiib <ootiib@hot.ee> - 2022-08-03 23:31 -0700
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-08-01 11:29 +0000
                Re: Differences between C and C++ Bo Persson <bo@bo-persson.se> - 2022-08-01 14:39 +0200
                Re: Differences between C and C++ Juha Nieminen <nospam@thanks.invalid> - 2022-08-02 05:43 +0000
                Re: Differences between C and C++ Manfred <noname@add.invalid> - 2022-08-03 01:13 +0200
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-08-03 09:34 +0300
              Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-29 09:22 +0000
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-07-29 13:53 +0300
                Re: Differences between C and C++ Paavo Helde <eesnimi@osa.pri.ee> - 2022-07-29 14:13 +0300
                Re: Differences between C and C++ Muttley@dastardlyhq.com - 2022-07-29 14:11 +0000
        Re: Differences between C and C++ Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2022-07-28 06:16 -0700

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