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Groups > comp.lang.c > #138961
| Subject | Re: A final word on casting. |
|---|---|
| Newsgroups | comp.lang.c |
| References | <af569436-b2e1-492b-8379-9f927013c590@googlegroups.com> <1YKTD.30400$CD3.15082@fx05.am4> <87k1k0ie66.fsf@bsb.me.uk> |
| From | Bart <bc@freeuk.com> |
| Message-ID | <NaNTD.109597$krL1.91@fx15.am4> (permalink) |
| Organization | virginmedia.com |
| Date | 2018-12-23 14:43 +0000 |
On 23/12/2018 13:08, Ben Bacarisse wrote:
> Bart <bc@freeuk.com> writes:
>> Try:
>>
>> printf("%d\n", (int)1.9999999999999999999999999999999);
>>
>> I seem to get the answer 2.
>
> Are you really puzzled by that?
Actually, yes. It means that (int)1.something will usually be 1 but
sometimes 2.
(I tried my own language to see if it does something different, and that
was worse as it seems to round to nearest int value [for x64 target
using 'cvtsd2si'], so this effect happens when you try the equivalent of
(int)1.4999999999999999999999.
However, with my big float library, the equivalent of
(int)1.99999999999... will always give 1 no matter how many 9s there are.)
> double usually has a wider range that float but it's no guaranteed. And
> the floating point type does not necessarily have an infinity. But on
> all the machines you care about, what you say is probably true.
The OP's comment about there being loss of precision from double to
float suggested they were talking about when float was a narrower type.
Usually that means the exponent is also narrower. (Not always; I've used
a software float32 type - the top half of a float64 - where the exponent
range is the same.)
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A final word on casting. chanrasjid@gmail.com - 2018-12-23 03:02 -0800
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 12:11 +0000
Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 13:08 +0000
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 14:43 +0000
Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 14:56 +0000
Re: A final word on casting. chanrasjid@gmail.com - 2018-12-23 07:08 -0800
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 15:55 +0000
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 16:07 +0000
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 08:21 -0800
Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 17:56 +0000
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 19:23 +0000
Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 20:12 +0000
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 14:06 -0800
Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-28 09:34 -0800
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-28 20:29 +0000
Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-28 15:07 -0800
Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-28 20:56 -0500
Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-29 09:22 -0800
Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2019-01-01 13:27 -0800
Re: A final word on casting. Bart <bc@freeuk.com> - 2019-01-02 01:07 +0000
Re: A final word on casting. Bart <bc@freeuk.com> - 2019-01-03 18:55 +0000
Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2019-01-03 22:27 -0500
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-04 16:25 -0500
Re: A final word on casting. Ike Naar <ike@iceland.freeshell.org> - 2018-12-28 19:10 +0000
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-28 12:33 -0800
Re: A final word on casting. "Chris M. Thomasson" <invalid_chris_thomasson@invalid.invalid> - 2018-12-23 14:11 -0800
Re: A final word on casting. Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-12-24 02:54 -0800
Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-24 03:24 -0800
Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-24 03:29 -0800
Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-24 03:45 -0800
Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-24 13:44 +0000
Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-24 08:51 -0500
Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-23 14:53 -0500
Re: A final word on casting. Robert Wessel <robertwessel2@yahoo.com> - 2018-12-24 09:39 -0600
Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-24 13:38 -0500
Re: A final word on casting. Manfred <noname@add.invalid> - 2018-12-23 21:22 +0100
Re: A final word on casting. Manfred <noname@add.invalid> - 2018-12-23 21:33 +0100
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 10:56 -0500
Re: A final word on casting. Sjouke Burry <burrynulnulfour@ppllaanneett.nnll> - 2018-12-23 17:18 +0100
Re: A final word on casting. Bart <bc@freeuk.com> - 2018-12-23 20:03 +0000
Re: A final word on casting. "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2018-12-28 14:47 -0500
Re: A final word on casting. Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-12-23 12:24 +0000
Re: A final word on casting. Richard Damon <Richard@Damon-Family.org> - 2018-12-23 07:28 -0500
Re: A final word on casting. Tim Rentsch <txr@alumni.caltech.edu> - 2018-12-28 07:50 -0800
Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-23 04:35 -0800
Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-23 04:42 -0800
Re: A final word on casting. fir <profesor.fir@gmail.com> - 2018-12-23 04:52 -0800
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-23 10:28 -0500
Re: A final word on casting. Barry Schwarz <schwarzb@dqel.com> - 2018-12-23 11:39 -0800
Re: A final word on casting. Ike Naar <ike@iceland.freeshell.org> - 2018-12-24 07:56 +0000
Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 14:03 -0800
Re: A final word on casting. Barry Schwarz <schwarzb@dqel.com> - 2018-12-24 14:39 -0800
Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 14:50 -0800
Re: A final word on casting. Keith Thompson <kst-u@mib.org> - 2018-12-24 15:34 -0800
Re: A final word on casting. Keith Thompson <kst-u@mib.org> - 2018-12-24 15:23 -0800
Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 20:34 -0800
Re: A final word on casting. Keith Thompson <kst-u@mib.org> - 2018-12-24 14:52 -0800
Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 20:25 -0800
Re: A final word on casting. James Kuyper <jameskuyper@alumni.caltech.edu> - 2018-12-24 17:52 -0500
Re: A final word on casting. luser droog <luser.droog@gmail.com> - 2018-12-24 21:27 -0800
Re: A final word on casting. luser droog <luser.droog@gmail.com> - 2018-12-24 21:39 -0800
Re: A final word on casting. chanrasjid@gmail.com - 2018-12-24 22:36 -0800
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