Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: when is casting (unsigned char*) to (signed char*) dangerous? |
| Date | 2012-01-26 11:32 -0800 |
| Organization | None to speak of |
| Message-ID | <lnty3i2rb7.fsf@nuthaus.mib.org> (permalink) |
| References | <j9ugaj$q30$4@speranza.aioe.org> <jfgdji$ilt$1@dont-email.me> <lnehuqx1a7.fsf@nuthaus.mib.org> <kfnvcny2yk8.fsf@x-alumni2.alumni.caltech.edu> |
Tim Rentsch <txr@alumni.caltech.edu> writes:
> Keith Thompson <kst-u@mib.org> writes:
>> Shao Miller <sha0.miller@gmail.com> writes:
>>> On 11/15/2011 14:59, tim wrote:
>>>> thanks in advance for your help, tim
>>>
>>> This one bothers me. We have:
>>> http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1310.htm
>>
>> That says:
>>
>> It is clear from the standard (specifically 6.2.6.2p1) that
>> unsigned integer types in general are not allowed to have trap
>> representations, and that unsigned char is not allowed to have
>> any padding bits.
>>
>> I don't believe that conclusion is correct. 6.2.6.2p1, both in C99 and
>> in C11 (N1570) defines a value of an unsigned type in terms of the value
>> bits, but unsigned types can also have padding bits, [snip]
>
> I assume he meant unsigned types cannot have trap representations
> considering just the value bits. Of course unsigned types can
> have TRs if they do have padding bits, but not if they don't
> (as is always the case for unsigned char).
I think that's a strained interpretation. It says "unsigned integer
types in general are not allowed to have trap representations";
I take that to mean that unsigned integer types are not allowed to
have trap representations (which is clearly incorrect).
I've just e-mailed the author; I'll let you know if I get a response.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Will write code for food.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
when is typecasting (unsigned char*) to (char*) dangerous? tim <nospam@nospam.com> - 2011-11-15 19:59 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? Kaz Kylheku <kaz@kylheku.com> - 2011-11-15 20:51 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? tim <nospam@nospam.com> - 2011-11-16 16:55 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? Kaz Kylheku <kaz@kylheku.com> - 2011-11-16 17:54 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 11:27 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Kaz Kylheku <kaz@kylheku.com> - 2011-11-16 19:49 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 11:52 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Kaz Kylheku <kaz@kylheku.com> - 2011-11-16 20:06 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 14:55 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 04:42 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? James Kuyper <jameskuyper@verizon.net> - 2011-11-16 15:15 -0500
Re: when is typecasting (unsigned char*) to (char*) dangerous? James Kuyper <jameskuyper@verizon.net> - 2011-11-16 15:24 -0500
Re: when is typecasting (unsigned char*) to (char*) dangerous? Harald van Dijk <truedfx@gmail.com> - 2011-11-16 12:41 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? James Kuyper <jameskuyper@verizon.net> - 2011-11-16 16:02 -0500
Re: when is typecasting (unsigned char*) to (char*) dangerous? Harald van Dijk <truedfx@gmail.com> - 2011-11-16 13:23 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 15:32 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Harald van Dijk <truedfx@gmail.com> - 2011-11-16 17:02 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? pete <pfiland@mindspring.com> - 2011-11-16 21:38 -0500
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 19:22 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Harald van Dijk <truedfx@gmail.com> - 2011-11-16 23:08 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 23:46 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Harald van Dijk <truedfx@gmail.com> - 2011-11-17 09:15 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-25 04:54 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Vincenzo Mercuri <vincenzo.mercuri@yahoo.it> - 2011-11-16 21:44 +0100
Re: when is typecasting (unsigned char*) to (char*) dangerous? Kenneth Brody <kenbrody@spamcop.net> - 2011-11-16 13:17 -0500
Re: when is typecasting (unsigned char*) to (char*) dangerous? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-11-16 00:58 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2011-11-16 01:36 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Markus Wichmann <nullplan@gmx.net> - 2011-11-16 13:28 +0100
Re: when is typecasting (unsigned char*) to (char*) dangerous? nroberts <roberts.noah@gmail.com> - 2011-11-16 08:14 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? BGB <cr88192@hotmail.com> - 2011-11-16 12:03 -0700
Re: when is typecasting (unsigned char*) to (char*) dangerous? blp@cs.stanford.edu (Ben Pfaff) - 2011-11-16 08:58 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Vincenzo Mercuri <vincenzo.mercuri@yahoo.it> - 2011-11-16 19:04 +0100
Re: when is typecasting (unsigned char*) to (char*) dangerous? Ben Pfaff <blp@cs.stanford.edu> - 2011-11-16 10:05 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-16 11:19 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Vincenzo Mercuri <vincenzo.mercuri@yahoo.it> - 2011-11-16 20:58 +0100
Re: when is typecasting (unsigned char*) to (char*) dangerous? Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-18 15:37 +0200
Re: when is typecasting (unsigned char*) to (char*) dangerous? Vincenzo Mercuri <vincenzo.mercuri@yahoo.it> - 2011-11-18 19:41 +0100
Re: when is typecasting (unsigned char*) to (char*) dangerous? Vincenzo Mercuri <vincenzo.mercuri@yahoo.it> - 2011-11-18 19:43 +0100
Re: when is typecasting (unsigned char*) to (char*) dangerous? Lauri Alanko <la@iki.fi> - 2011-11-17 19:09 +0000
Re: when is typecasting (unsigned char*) to (char*) dangerous? Harald van Dijk <truedfx@gmail.com> - 2011-11-17 11:44 -0800
Re: when is typecasting (unsigned char*) to (char*) dangerous? Keith Thompson <kst-u@mib.org> - 2011-11-17 13:16 -0800
Re: when is casting (unsigned char*) to (signed char*) dangerous? Shao Miller <sha0.miller@gmail.com> - 2012-01-22 02:22 -0500
Re: when is casting (unsigned char*) to (signed char*) dangerous? Harald van Dijk <haraldvdijk@gmail.com> - 2012-01-22 12:14 -0800
Re: when is casting (unsigned char*) to (signed char*) dangerous? Keith Thompson <kst-u@mib.org> - 2012-01-23 00:37 -0800
Re: when is casting (unsigned char*) to (signed char*) dangerous? Jens Gustedt <jens.gustedt@loria.fr> - 2012-01-24 15:10 +0100
Re: when is casting (unsigned char*) to (signed char*) dangerous? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-26 08:55 -0800
Re: when is casting (unsigned char*) to (signed char*) dangerous? Keith Thompson <kst-u@mib.org> - 2012-01-26 11:32 -0800
Re: when is casting (unsigned char*) to (signed char*) dangerous? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-31 21:57 -0800
Re: when is casting (unsigned char*) to (signed char*) dangerous? Shao Miller <sha0.miller@gmail.com> - 2012-02-01 01:12 -0500
Re: when is casting (unsigned char*) to (signed char*) dangerous? Tim Rentsch <txr@alumni.caltech.edu> - 2012-01-26 08:48 -0800
csiph-web