Re: determines if it is a signed type

From	Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups	comp.lang.c
Subject	Re: determines if it is a signed type
Date	2015-05-18 21:15 +0100
Organization	A noiseless patient Spider
Message-ID	<87fv6tlk00.fsf@bsb.me.uk> (permalink)
References	<6a4be947-376c-466e-aa9f-78a6e174725c@googlegroups.com> <mjbai5$u51$1@speranza.aioe.org> <87oalilmz9.fsf@bsb.me.uk> <87vbfqqqtz.fsf@kst-u.example.com>

Show all headers | View raw

Keith Thompson <kst-u@mib.org> writes:

> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>> Morris Dovey <mrdovey@iedu.com> writes:
>>> On 5/17/15 12:07 PM, asetofsymbols@gmail.com wrote:
>>>> Is there any better way?
>>>
>>> Of course - look at the declaration!
>>>
>>> If you’re too lazy to do that, you could try (untested)
>>>
>>> #define IS_SIGNED(t) (((t) < 0) || (-(t) < 0) || (~(t) < 0))
>>
>> Hmm...  Not, I think, 100% portable in that on a ones' complement
>> machine with "normal" negative zeros, C permits ~t to be zero (i.e. not
>> < 0).
>
> And it has undefined behavior on a two's-complement system if t is
> INT_MIN.

How so?

<snip>
-- 
Ben.

Thread

determines if it is a signed type asetofsymbols@gmail.com - 2015-05-17 10:07 -0700
  Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-17 18:12 +0100
    Re: determines if it is a signed type asetofsymbols@gmail.com - 2015-05-17 10:34 -0700
      Re: determines if it is a signed type asetofsymbols@gmail.com - 2015-05-17 11:09 -0700
      Re: determines if it is a signed type Kusalananda <kusalananda@example.com> - 2015-05-17 18:22 +0000
        Re: determines if it is a signed type asetofsymbols@gmail.com - 2015-05-17 11:31 -0700
          Re: determines if it is a signed type Kusalananda <kusalananda@example.com> - 2015-05-17 19:59 +0000
  Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-17 13:12 -0700
  Re: determines if it is a signed type Morris Dovey <mrdovey@iedu.com> - 2015-05-17 19:08 -0500
    Re: determines if it is a signed type Morris Dovey <mrdovey@iedu.com> - 2015-05-17 19:46 -0500
    Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-18 01:59 +0100
      Re: determines if it is a signed type Morris Dovey <mrdovey@iedu.com> - 2015-05-17 20:10 -0500
      Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-18 00:37 -0700
        Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-18 21:15 +0100
          Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-18 15:15 -0700
        Re: determines if it is a signed type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-18 21:51 +0000
          Re: determines if it is a signed type James Kuyper <jameskuyper@verizon.net> - 2015-05-18 18:00 -0400
      Re: determines if it is a signed type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-18 14:37 +0000
        Re: determines if it is a signed type jacobnavia <jacob@jacob.remcomp.fr> - 2015-05-18 17:09 +0200
          Re: determines if it is a signed type glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-18 18:14 +0000
    Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 06:34 +0100
      Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-18 00:43 -0700
        Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 13:56 +0100
          Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-18 08:00 -0700
            Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 20:35 +0100
              Re: determines if it is a signed type jacobnavia <jacob@jacob.remcomp.fr> - 2015-05-18 23:08 +0200
                Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-18 22:32 +0100
                Re: determines if it is a signed type jacobnavia <jacob@jacob.remcomp.fr> - 2015-05-19 00:44 +0200
                Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-19 00:05 +0100
                Re: determines if it is a signed type jacobnavia <jacob@jacob.remcomp.fr> - 2015-05-19 01:43 +0200
                Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-19 01:08 +0100
                Re: determines if it is a signed type "Bartc" <bartc@freeuk.com> - 2015-05-19 11:33 +0100
                Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-19 08:15 -0700
                Re: determines if it is a signed type "Bartc" <bartc@freeuk.com> - 2015-05-19 19:36 +0100
                Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-19 11:55 -0700
                Re: determines if it is a signed type jacobnavia <jacob@jacob.remcomp.fr> - 2015-05-19 11:39 +0200
                Re: determines if it is a signed type "Bartc" <bartc@freeuk.com> - 2015-05-19 11:44 +0100
                Re: determines if it is a signed type jacobnavia <jacob@jacob.remcomp.fr> - 2015-05-19 12:11 +0200
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-19 05:45 -0700
                Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-19 15:03 +0100
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-19 08:46 -0700
                Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-19 17:08 +0100
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-19 09:52 -0700
                Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-19 20:36 +0100
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-20 07:40 -0700
                Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-20 23:12 +0100
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-21 13:52 -0700
                Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-21 22:48 +0100
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-22 05:50 -0700
                Re: determines if it is a signed type Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-22 23:14 +0100
                Re: determines if it is a signed type jadill33@gmail.com - 2015-05-26 14:31 -0700
                Re: determines if it is a signed type Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-22 23:32 -0700
                Re: determines if it is a signed type David Brown <david.brown@hesbynett.no> - 2015-05-20 12:26 +0200
                Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-19 15:28 +0100
                Re: determines if it is a signed type raltbos@xs4all.nl (Richard Bos) - 2015-05-23 10:37 +0000
              Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-18 15:21 -0700
                Re: determines if it is a signed type Richard Heathfield <rjh@cpax.org.uk> - 2015-05-19 00:04 +0100
                Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-19 08:03 -0700
                Re: determines if it is a signed type David Brown <david.brown@hesbynett.no> - 2015-05-19 08:47 +0200
                Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-19 08:07 -0700
          Re: determines if it is a signed type James Kuyper <jameskuyper@verizon.net> - 2015-05-18 11:28 -0400
    Re: determines if it is a signed type Keith Thompson <kst-u@mib.org> - 2015-05-18 00:40 -0700

csiph-web