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Groups > comp.lang.c > #392898
| From | Keith Thompson <Keith.S.Thompson+u@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: integer divided by zero |
| Date | 2025-04-25 13:31 -0700 |
| Organization | None to speak of |
| Message-ID | <87o6wkouea.fsf@nosuchdomain.example.com> (permalink) |
| References | <vughb7$g6cm$1@dont-email.me> <87selwoydy.fsf@nosuchdomain.example.com> <vugo19$m2n2$1@dont-email.me> |
Thiago Adams <thiago.adams@gmail.com> writes:
> Em 4/25/2025 4:05 PM, Keith Thompson escreveu:
>> Thiago Adams <thiago.adams@gmail.com> writes:
>>> Does anyone know of any platform where integer division by zero
>>> returns a number, or in other words, where it's not treated as an
>>> error? I'm asking because division by zero is undefined behaviour, but
>>> I think division by a constant zero should be a constraint instead.
>> Division by a constant zero is a constraint violation in a context
>> that requires a constant expression.
>
> Consider this sample
>
> int main(){
> int a[1/0];
> }
>
> 1/0 does not have a value in compile time,
> So I believe compilers are making "a" a VLA because 1/0 is
> not constant.
1/0 is not a constant expression.
A conforming compiler that supports VLAs (C99, or optionally C11 or
later) would make `a` a VLA, with undefined behavior at runtime when
1/0 is evaluated. For a conforming compiler that doesn't support
VLAs (C89/C90, or optionally C11 or later) the declaration is a
constraint violation.
> (But what old c89 compilers where doing in this case?)
>
> This sample is a motivation to make integer divided by
> zero a constrain.
I consider it motivation not to write code like that.
Sure, I wouldn't mind if using / or % with a right operand
that's a constant expression with value zero (either integer or
floating-point) were a constraint violation, but some compilers
are going to warn about it anyway, and I doubt that such a language
change would catch many errors.
--
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
integer divided by zero Thiago Adams <thiago.adams@gmail.com> - 2025-04-25 14:38 -0300
Re: integer divided by zero David Brown <david.brown@hesbynett.no> - 2025-04-25 19:50 +0200
Re: integer divided by zero Thiago Adams <thiago.adams@gmail.com> - 2025-04-25 16:37 -0300
Re: integer divided by zero Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-04-25 13:32 -0700
Re: integer divided by zero Thiago Adams <thiago.adams@gmail.com> - 2025-04-26 12:30 -0300
Re: integer divided by zero gazelle@shell.xmission.com (Kenny McCormack) - 2025-04-26 16:27 +0000
Re: integer divided by zero Kaz Kylheku <643-408-1753@kylheku.com> - 2025-04-26 17:01 +0000
Re: integer divided by zero Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-04-25 12:05 -0700
Re: integer divided by zero Thiago Adams <thiago.adams@gmail.com> - 2025-04-25 16:32 -0300
Re: integer divided by zero Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-04-25 13:31 -0700
Re: integer divided by zero Kaz Kylheku <643-408-1753@kylheku.com> - 2025-04-25 21:36 +0000
Re: integer divided by zero Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-04-25 16:09 -0700
Re: integer divided by zero Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-05-14 01:09 -0700
Re: integer divided by zero Thiago Adams <thiago.adams@gmail.com> - 2025-04-28 11:05 -0300
Re: integer divided by zero Rosario19 <Ros@invalid.invalid> - 2025-04-30 12:41 +0200
Re: integer divided by zero David Brown <david.brown@hesbynett.no> - 2025-04-30 13:35 +0200
Re: integer divided by zero John McCue <jmccue@magnetar.jmcunx.com> - 2025-04-25 19:41 +0000
Re: integer divided by zero antispam@fricas.org (Waldek Hebisch) - 2025-04-26 09:57 +0000
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-27 15:33 +0200
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-27 15:46 +0200
Did you get confused again? You seem eaily bewildered. (Was: integer divided by zero) gazelle@shell.xmission.com (Kenny McCormack) - 2025-04-27 14:43 +0000
Re: Did you get confused again? You seem eaily bewildered. (Was: integer divided by zero) Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-27 16:54 +0200
Re: Did you get confused again? You seem eaily bewildered. (Was: integer divided by zero) scott@slp53.sl.home (Scott Lurndal) - 2025-04-27 16:16 +0000
Re: Did you get confused again? You seem eaily bewildered. (Was: integer divided by zero) Kaz Kylheku <643-408-1753@kylheku.com> - 2025-04-27 16:23 +0000
Re: Did you get confused again? You seem eaily bewildered. (Was: integer divided by zero) Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-27 20:28 +0200
Re: Did you get confused again? You seem eaily bewildered. (Was: integer divided by zero) scott@slp53.sl.home (Scott Lurndal) - 2025-04-27 22:52 +0000
Re: Did you get confused again? You seem eaily bewildered. antispam@fricas.org (Waldek Hebisch) - 2025-04-28 10:41 +0000
Re: Did you get confused again? You seem eaily bewildered. antispam@fricas.org (Waldek Hebisch) - 2025-04-28 10:12 +0000
Re: Did you get confused again? You seem eaily bewildered. Rosario19 <Ros@invalid.invalid> - 2025-04-30 09:16 +0200
Re: Did you get confused again? You seem eaily bewildered. Richard Heathfield <rjh@cpax.org.uk> - 2025-04-30 08:36 +0100
Re: Did you get confused again? You seem eaily bewildered. antispam@fricas.org (Waldek Hebisch) - 2025-04-28 10:39 +0000
Re: Did you get confused again? You seem eaily bewildered. Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 12:50 +0200
Re: integer divided by zero Richard Heathfield <rjh@cpax.org.uk> - 2025-04-28 08:54 +0100
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 12:49 +0200
Re: integer divided by zero Richard Heathfield <rjh@cpax.org.uk> - 2025-04-28 12:01 +0100
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 13:27 +0200
Re: integer divided by zero Richard Damon <richard@damon-family.org> - 2025-04-28 07:15 -0400
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 13:28 +0200
Re: integer divided by zero scott@slp53.sl.home (Scott Lurndal) - 2025-04-28 14:28 +0000
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 16:51 +0200
Re: integer divided by zero Michael S <already5chosen@yahoo.com> - 2025-04-28 18:03 +0300
Re: integer divided by zero scott@slp53.sl.home (Scott Lurndal) - 2025-04-28 16:35 +0000
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 18:38 +0200
Re: integer divided by zero Muttley@DastardlyHQ.org - 2025-04-28 17:02 +0000
Re: integer divided by zero antispam@fricas.org (Waldek Hebisch) - 2025-04-28 14:44 +0000
Re: integer divided by zero Bonita Montero <Bonita.Montero@gmail.com> - 2025-04-28 16:52 +0200
Re: integer divided by zero Richard Heathfield <rjh@cpax.org.uk> - 2025-04-28 14:52 +0100
Re: integer divided by zero Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-04-28 13:44 -0700
Re: integer divided by zero Vir Campestris <vir.campestris@invalid.invalid> - 2025-05-03 21:47 +0100
Re: integer divided by zero Michael S <already5chosen@yahoo.com> - 2025-05-03 23:58 +0300
Re: integer divided by zero goldside000@outlook.com - 2025-05-31 18:56 +0000
Re: integer divided by zero Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-31 14:07 -0700
Re: integer divided by zero scott@slp53.sl.home (Scott Lurndal) - 2025-05-31 21:53 +0000
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