Re: Whaddaya think?

From	Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: Whaddaya think?
Date	2024-06-16 23:20 -0700
Organization	None to speak of
Message-ID	<877ceo2iqq.fsf@nosuchdomain.example.com> (permalink)
References	(6 earlier) <v4ltuj$3trj2$1@dont-email.me> <87y17530a0.fsf@nosuchdomain.example.com> <v4mb92$3ak$1@dont-email.me> <87tths39yy.fsf@nosuchdomain.example.com> <v4oi9f$gnf3$1@dont-email.me>

Show all headers | View raw

Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> On 16.06.2024 22:32, Keith Thompson wrote:
>> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>>> [...] K&R at
>>> least seems to say that 'void' can only be declared for the
>>> return type of functions that do not return anything.
>>> [...]
>> 
>> No version of C has ever permitted "void main" except when an
>> implementation documents and permits it.  [...]
>
> I cannot comment on main() being handled differently than
> other C functions. I was just quoting my old copy of K&R.

First or second edition?

But main() *is* handled differently than other functions, and
that's important to understand.  It's effectively called by the
environment, which means that your definition has to cooperate
with what the environment expects.  What's slightly weird about
it is that it can be defined in (at least) two different ways,
with or without argc and argv.

Similarly, signal handlers and qsort comparison functions are code
that you write that's invoked by the environment or the runtime
library.  You don't get to change what type they return and expect
your program to work correctly.

This is all in the "Program startup" subsection of section 5 of any
edition or draft of the C standard, and it hasn't changed much from
C89 (where it's in section 2) up to the latest post-C23 draft.

> I don't understand what you mean with "no version of C has
> ever permitted", given that my C compiler doesn't complain.

I mean that no edition of the C standard has ever mentioned "void
main".  The only explicitly permitted return type has been int since
the first standard in 1989.  In K&R1, there was no void keyword.
(I think the "void" keyword was introduced before 1989, but the
ANSI C standard formalized it.)

"void main" does not require a diagnostic, so perhaps "permitted" was
not the best word.  But a conforming compiler can reject a program
that uses "void main" (that's one of the allowed consequences of
undefined behavior).

> WRT return value to the environment I'd expect any random
> or arbitrary value being returned in case that non had been
> explicitly specified to be returned.

Feel free to expect that.  The standard says that, unless the
implementation documents that "void main" is permitted, the behavior
is undefined.  Not just the status, the behavior of the program.

It happens that, for most compilers, the actual behavior of "void
main" is relatively harmless -- but why take that risk?

> If I want a defined exit status (which is what I usually
> want) I specify 'int main (...)' and provide an explicit
> return statement (or exit() call).

Why would you ever not want a defined exit status, given that it's
easier to have one than not to have one?  (Since C99 an explicit
return or exit() is optional.)  I can't think of any reason *at all*
to use "void main" in C with a hosted implementation.  Can you?
(If you don't care about the exit status, you can just write
"int main" and not bother with a return statement or exit() call.
The exit status will be 0, but that's not a problem if you don't
care about it.)

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
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

Thread

Whaddaya think? DFS <nospam@dfs.com> - 2024-06-15 15:36 -0400
  Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-15 22:33 +0100
  Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-15 23:03 +0100
    Re: Whaddaya think? bart <bc@freeuk.com> - 2024-06-16 00:22 +0100
      Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-16 10:30 +0100
    Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 11:52 -0400
      Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-17 00:17 +0100
        Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 08:49 -0400
  Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 15:22 -0700
    Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 12:20 -0400
      Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 13:54 -0700
      Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-16 22:41 -0400
        Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-16 22:45 -0700
        Re: Whaddaya think? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-17 07:39 +0000
          Re: Whaddaya think? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-17 01:22 -0700
          Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 09:50 -0400
            Re: Whaddaya think? Richard Harnden <richard.nospam@gmail.invalid> - 2024-06-17 16:23 +0100
              Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-17 18:46 +0200
              Re: Whaddaya think? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-22 22:14 +0000
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-22 17:10 -0700
                Re: Whaddaya think? Phil Carmody <pc+usenet@asdf.org> - 2024-06-23 11:20 +0300
          Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 00:19 -0700
            Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 03:10 -0700
              Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 17:24 -0700
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 17:55 -0700
                Re: Whaddaya think? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-19 01:58 +0000
        Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 08:50 -0400
          Re: Whaddaya think? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-17 15:41 +0100
            Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 08:12 +0200
              Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 03:07 -0700
      Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 00:30 -0400
  Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 01:56 +0300
    Re: Whaddaya think? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-16 03:26 +0000
      Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 05:41 +0200
        Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 21:17 -0700
          Re: Whaddaya think? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-16 04:41 +0000
          Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 06:44 +0200
            Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 11:09 -0400
              Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-16 17:56 +0200
                Re: Whaddaya think? bart <bc@freeuk.com> - 2024-06-16 18:14 +0100
                Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-17 14:44 +0200
                Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 09:52 -0400
        Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 06:51 +0200
          Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 22:21 -0700
            Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 07:41 +0200
              Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-15 22:49 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 11:29 +0200
                Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-16 16:04 +0100
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 17:13 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 13:32 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 07:41 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 23:20 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 09:16 +0200
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 09:38 -0400
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 16:17 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 07:09 +0200
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-18 03:25 -0400
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 02:57 -0700
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 16:15 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 08:02 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-18 19:07 -0700
                Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-19 09:50 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-19 13:13 -0700
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 02:21 -0400
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 09:22 +0200
              Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 11:11 +0300
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 11:07 +0200
                Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 12:38 +0300
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 12:03 +0200
                Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 14:31 +0300
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 17:37 +0200
                Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-17 00:45 +0300
              Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 17:06 -0700
                Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-16 22:40 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 07:52 +0200
                Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 09:45 -0400
                Re: Whaddaya think? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-06-17 13:16 -0700
                Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-17 17:07 -0400
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 15:48 -0700
                Re: Whaddaya think? scott@slp53.sl.home (Scott Lurndal) - 2024-06-17 22:48 +0000
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-17 15:44 -0700
                Re: Whaddaya think? David Brown <david.brown@hesbynett.no> - 2024-06-18 15:00 +0200
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-18 06:57 +0200
                Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 00:25 -0700
                Re: Whaddaya think? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-17 02:38 -0400
                Re: Whaddaya think? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-18 17:01 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 07:48 +0200
                Re: Whaddaya think? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-16 23:29 -0700
                Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-17 09:35 +0200
        Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-16 08:19 +0100
        Re: Whaddaya think? Michael S <already5chosen@yahoo.com> - 2024-06-16 10:44 +0300
          Re: Whaddaya think? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-06-16 11:13 +0200
    Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-16 11:03 -0400
  Re: Whaddaya think? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-06-16 15:52 +0000
    Re: Whaddaya think? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-06-16 17:17 +0100
    Re: Whaddaya think? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-18 08:06 +0000
    Re: Whaddaya think? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-06-25 17:37 +0000
      Re: Whaddaya think? DFS <nospam@dfs.com> - 2024-06-25 14:09 -0400
        Re: Whaddaya think? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-06-25 18:11 +0000

csiph-web