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From: KK6GM <mjsilva@scriptoriumdesigns.com>
Subject: Re: Fun with C
Date: Sat, 16 Apr 2011 23:26:14 -0700 (PDT)
Date: 2011-04-16T23:26:14-07:00	[thread overview]
Message-ID: <54108d8d-4e7c-4901-bd5e-819d27720d48@a11g2000pro.googlegroups.com> (raw)
In-Reply-To: 27cf3992-4132-4483-9110-adc7a089cd4a@e8g2000vbz.googlegroups.com

On Apr 16, 10:02 am, "George P." <george.p...@gmail.com> wrote:
> Spend few days chasing bug in embedded C project which can drilled
> down to this. Consider the following program, and all reasonable men
> will expect the result to be negative.  Not in C, and it is not a
> compiler bug :-(
>
> And offcorse none of the three comilers I cheched did not bother to
> issue a warning at least..
>
> #include <stdio.h>
>
> int main()
> {
>      unsigned n = 128;
>      int i = -2048;
>      int r;
>
>      r = i / n;
>
>      printf("R = %d\n", r);
>
>      return 0;
>
>
>
> }- Hide quoted text -
>
> - Show quoted text -

Wow and wow.  I've been writing C all my adult life and I didn't
realize this could or would happen.  I would have said that the
unsigned would be promoted to signed.

I'm going to include this example in my push to use Ada in our next
project.



  parent reply	other threads:[~2011-04-17  6:26 UTC|newest]

Thread overview: 124+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-16 17:02 Fun with C George P.
2011-04-16 20:04 ` Nasser M. Abbasi
2011-04-16 21:12   ` Ludovic Brenta
2011-04-16 21:42     ` jimmaureenrogers
2011-04-17  7:17     ` Georg Bauhaus
2011-04-17  8:29       ` Martin
2011-04-17 18:19       ` George P.
2011-04-17  8:40     ` Georg Bauhaus
2011-04-18  1:04     ` Peter C. Chapin
2011-04-18  2:14       ` George P.
2011-04-16 22:03   ` George P.
2011-04-17  6:26 ` KK6GM [this message]
2011-04-17  6:59   ` Georg Bauhaus
2011-04-17 16:15     ` KK6GM
2011-04-17 19:35       ` Elias Salomão Helou Neto
2011-04-17 20:18         ` KK6GM
2011-04-18 19:47           ` Elias Salomão Helou Neto
2011-04-18 22:11             ` Peter C. Chapin
2011-04-17 22:26         ` Georg Bauhaus
2011-04-18 19:12           ` Elias Salomão Helou Neto
2011-04-18 20:56             ` KK6GM
2011-04-18 21:01             ` Georg Bauhaus
2011-04-18 21:20               ` Nasser M. Abbasi
2011-04-19  2:43                 ` George P.
2011-04-19 18:05                   ` Vinzent Hoefler
2011-04-19 19:34                     ` George P.
2011-04-19 20:08                       ` Georg Bauhaus
2011-04-19  1:10               ` Elias Salomão Helou Neto
2011-04-19 14:28                 ` Georg Bauhaus
2011-04-19 17:40                   ` Jeffrey Carter
2011-04-21 14:52                   ` Elias Salomão Helou Neto
2011-04-21 18:58                     ` Georg Bauhaus
2011-04-21 19:27                       ` Hyman Rosen
2011-04-28  5:13                         ` David Thompson
2011-04-28 13:41                           ` Hyman Rosen
2011-05-05  8:39                             ` David Thompson
2011-04-25 11:06                 ` Paul Colin Gloster
2011-04-25 11:00                   ` Georg Bauhaus
2011-04-25 12:12                     ` Martin
2011-04-25 18:39                       ` Paul Colin Gloster
2011-05-08 23:41           ` wilso
2011-05-20 10:41             ` Yannick Duchêne (Hibou57)
2011-05-20 16:04               ` Yannick Duchêne (Hibou57)
2011-04-18  0:12         ` George P.
2011-04-18 19:24           ` Elias Salomão Helou Neto
2011-04-19  1:22             ` George P.
2011-04-19  2:06               ` Elias Salomão Helou Neto
2011-04-19  2:37                 ` Bill Findlay
2011-04-19  3:00                 ` George P.
2011-04-17 19:19 ` Elias Salomão Helou Neto
2011-04-17 23:26   ` Gautier write-only
2011-04-17 23:43     ` Nasser M. Abbasi
2011-04-18 19:16       ` Elias Salomão Helou Neto
2011-04-18 23:10         ` Randy Brukardt
2011-04-19  1:36           ` Elias Salomão Helou Neto
2011-04-20 23:14             ` Randy Brukardt
2011-04-21 16:19               ` Elias Salomão Helou Neto
2011-04-21 17:36                 ` Dmitry A. Kazakov
2011-04-21 17:43                   ` Hyman Rosen
2011-04-21 19:44                     ` Dmitry A. Kazakov
2011-04-22  6:16                   ` Elias Salomão Helou Neto
2011-04-22  9:21                     ` Dmitry A. Kazakov
2011-04-22 13:18                       ` Hyman Rosen
2011-04-22 15:17                         ` Dmitry A. Kazakov
2011-04-23  2:08                       ` Elias Salomão Helou Neto
2011-04-23  7:23                         ` Dmitry A. Kazakov
2011-04-23  9:42                           ` Georg Bauhaus
2011-04-23 10:23                             ` Dmitry A. Kazakov
2011-04-23 18:37                           ` Elias Salomão Helou Neto
2011-04-23 21:36                             ` Dmitry A. Kazakov
2011-04-24 11:27                               ` Peter C. Chapin
2011-04-24 13:53                                 ` Dmitry A. Kazakov
2011-04-24 19:07                                   ` Nasser M. Abbasi
2011-04-24 19:46                                     ` Dmitry A. Kazakov
2011-04-24 21:20                                       ` Nasser M. Abbasi
2011-04-24 22:33                                         ` Elias Salomão Helou Neto
2011-04-25  7:09                                         ` Dmitry A. Kazakov
2011-04-25 20:46                                           ` Maciej Sobczak
2011-04-25 21:19                                             ` George P.
2011-04-26  6:18                                             ` Dmitry A. Kazakov
2011-04-26  6:58                                               ` Nasser M. Abbasi
2011-04-26  8:39                                                 ` Dmitry A. Kazakov
2011-04-26 20:57                                               ` Maciej Sobczak
2011-04-27  8:00                                                 ` Dmitry A. Kazakov
2011-04-27  8:19                                                   ` Georg Bauhaus
2011-04-27  9:32                                                     ` Dmitry A. Kazakov
2011-04-28  7:02                                                   ` Maciej Sobczak
2011-04-28  7:41                                                     ` Dmitry A. Kazakov
2011-04-28 10:24                                                       ` Peter C. Chapin
2011-04-28 13:56                                                         ` Dmitry A. Kazakov
2011-05-03  1:19                                                           ` Nasser M. Abbasi
2011-05-03  6:05                                                             ` J-P. Rosen
2011-05-03  6:15                                                               ` Ludovic Brenta
2011-05-03  7:43                                                                 ` Dmitry A. Kazakov
2011-05-03 15:34                                                               ` Bill Findlay
2011-05-03  7:53                                                             ` Georg Bauhaus
2011-05-03  9:29                                                             ` Simon Wright
2011-04-24 22:23                                       ` Elias Salomão Helou Neto
2011-04-25  7:10                                         ` Dmitry A. Kazakov
2011-04-24 20:37                                 ` Georg Bauhaus
2011-04-23 15:23                         ` George P.
2011-04-23 17:28                           ` Nasser M. Abbasi
2011-04-23 17:52                             ` Dmitry A. Kazakov
2011-04-23 18:11                               ` Nasser M. Abbasi
2011-04-23 20:47                               ` George P.
2011-04-24 11:36                                 ` Peter C. Chapin
2011-04-25 11:43                                   ` Paul Colin Gloster
2011-04-23 16:56                         ` Nasser M. Abbasi
2011-04-23 18:45                           ` Elias Salomão Helou Neto
2011-04-22 12:15                     ` J-P. Rosen
2011-04-22 14:56                       ` Niklas Holsti
2011-04-21 23:29                 ` Randy Brukardt
2011-04-22  6:29                   ` Elias Salomão Helou Neto
2011-04-25 11:22                 ` Paul Colin Gloster
2011-04-18 19:13     ` Elias Salomão Helou Neto
2011-04-20  5:11   ` J-P. Rosen
2011-04-20 15:45     ` KK6GM
2011-04-20 19:04     ` Vinzent Hoefler
2011-04-20 21:09       ` Georg Bauhaus
2011-04-20 22:52         ` Vinzent Hoefler
2011-04-21 14:18     ` Elias Salomão Helou Neto
2011-04-21 16:22       ` Vinzent Hoefler
2011-04-21 19:25         ` John B. Matthews
2011-04-23 23:07 ` Gerd
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