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| From | Eric Sosman <esosman@ieee-dot-org.invalid> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: c99 and the lack of warnings when int operations are applied to a bool |
| Date | 2012-04-26 21:29 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <jncspr$on8$1@dont-email.me> (permalink) |
| References | <jki5iu$jea$1@dont-email.me> <jkinde$or2$1@speranza.aioe.org> <jksrbo$p2a$1@dont-email.me> <jnbd7q$17a$1@dont-email.me> <jnbhej$ovn$1@dont-email.me> |
On 4/26/2012 9:09 AM, James Kuyper wrote:
> On 04/26/2012 07:57 AM, Eric Sosman wrote:
>> On 3/27/2012 12:53 PM, mathog wrote:
> ...
>>> My point exactly, even if a bool in some implementation is stored more
>>> or less the same way as an integer type, none of the integer operations
>>> should be applicable to it.
>>
>> bool expensive(), complicated(), long_winded();
>> switch (4*expensive() + 2*complicated() + long_winded()) {
>> case 0: ...
>> case 1: ...
>> case 2: ...
>> case 3: ...
>> case 4: ...
>> case 5: ...
>> case 6: ...
>> case 7: ...
>> }
>>
>> I'll grant that this sort of situation doesn't arise all that often,
>> and I'll grant that there are other ways to write the logic (there's
>> usually more than one way to do something in C), but I think you're
>> going overboard in trying to legislate the pattern out of existence.
>
> If bool were a strictly logical type, on which no arithmetic could be
> performed, that pattern would still be allowed, the syntax would just be
> slightly more complicated:
>
> (expensive()?4:0) + (complicated()?2:0) + (long_winded()?1:0)
"I'll grant that there are other ways to write the logic," as
a person I deeply respect once wrote.
Here's another example where arithmetic on bool is handy:
const int days_in_month[2][12] = {
{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};
bool is_leap_year = ...;
int month = ...;
int days = days_in_month[is_leap_year][month - 1];
"One (int) cast and all's well," but don't forget the skeptical
glance one usually casts upon casts...
--
Eric Sosman
esosman@ieee-dot-org.invalid
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c99 and the lack of warnings when int operations are applied to a bool mathog <dmathog@gmail.com> - 2012-03-23 08:40 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-03-23 12:07 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-23 21:45 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Robert Wessel <robertwessel2@yahoo.com> - 2012-03-23 17:17 -0500
Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-23 23:29 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Ian Collins <ian-news@hotmail.com> - 2012-03-24 11:48 +1300
Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-24 23:47 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Willem <willem@toad.stack.nl> - 2012-03-25 09:05 +0000
Re: c99 and the lack of warnings when int operations are applied to a bool "BartC" <bc@freeuk.com> - 2012-03-25 11:30 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-25 21:05 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Lowell Gilbert <lgusenet@be-well.ilk.org> - 2012-03-25 16:15 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-25 22:14 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-03-25 23:46 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-26 12:05 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Lowell Gilbert <lgusenet@be-well.ilk.org> - 2012-03-26 15:22 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Gareth Owen <gwowen@gmail.com> - 2012-03-25 11:44 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-03-25 13:06 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Tim Rentsch <txr@alumni.caltech.edu> - 2012-03-27 11:12 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool Robert Wessel <robertwessel2@yahoo.com> - 2012-03-24 01:15 -0500
Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-03-24 23:29 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool mathog <dmathog@gmail.com> - 2012-03-27 09:53 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-03-27 11:07 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-03-27 14:16 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-26 07:57 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool jacob navia <jacob@spamsink.net> - 2012-04-26 14:08 +0200
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-26 09:09 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-26 21:29 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-26 21:58 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-26 22:32 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-27 06:31 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Lanarcam <lanarcam1@yahoo.fr> - 2012-04-27 19:26 +0200
Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-04-27 11:28 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool Lanarcam <lanarcam1@yahoo.fr> - 2012-04-27 20:51 +0200
Re: c99 and the lack of warnings when int operations are applied to a bool ImpalerCore <jadill33@gmail.com> - 2012-04-27 12:17 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool Jens Gustedt <jens.gustedt@loria.fr> - 2012-04-28 09:17 +0200
Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-04-28 13:26 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool Willem <willem@toad.stack.nl> - 2012-04-27 18:11 +0000
Re: c99 and the lack of warnings when int operations are applied to a bool ImpalerCore <jadill33@gmail.com> - 2012-04-27 12:05 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-27 15:32 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Willem <willem@toad.stack.nl> - 2012-04-27 20:16 +0000
Re: c99 and the lack of warnings when int operations are applied to a bool James Kuyper <jameskuyper@verizon.net> - 2012-04-27 16:45 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Rui Maciel <rui.maciel@gmail.com> - 2012-04-27 21:26 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-27 21:18 -0400
Re: c99 and the lack of warnings when int operations are applied to a bool Rui Maciel <rui.maciel@gmail.com> - 2012-04-27 21:33 +0100
Re: c99 and the lack of warnings when int operations are applied to a bool Keith Thompson <kst-u@mib.org> - 2012-04-27 15:36 -0700
Re: c99 and the lack of warnings when int operations are applied to a bool ImpalerCore <jadill33@gmail.com> - 2012-04-27 08:31 -0700
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