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Groups > comp.lang.c++ > #84144
| From | Ben <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: C++ (and some C) quiz questions |
| Date | 2022-05-17 11:12 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <87czgcqxgc.fsf@bsb.me.uk> (permalink) |
| References | <t5tc3s$164p$1@gioia.aioe.org> <t5u3kb$h0k$1@dont-email.me> <t5u6es$a95$1@dont-email.me> <t5u6uh$e6l$1@dont-email.me> <t5v928$1h9n$1@gioia.aioe.org> |
Juha Nieminen <nospam@thanks.invalid> writes:
> Christian Gollwitzer <auriocus@gmx.de> wrote:
>>> Re #5, I guess that the problem with
>>>
>>> long double value = 0.1;
>>>
>>> ... is that when `long double` doesn't have the same representation as
>>> `double`, one may get a less precise value than with
>>>
>>> long double value = 0.1L;
>>>
>>> Is that it?
>>
>> That's how I see it. 0.1 is a double constant and since 1/10 can't be
>> represented exactly in binary (assuming binary floats), the value in
>> "value" is not the closes approximation to 0.1 possible, which is 0.1L.
>
> It's easy to make such mistakes, and not just in variable initialization,
> but also pretty much anywhere where a literal is used, like:
>
> x = y * 0.1; // If x and y are long double, precision is lost
7.4 Usual arithmetic conversions
(1.2) — If either operand is of type long double, the other shall be
converted to long double.
--
Ben.
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C++ (and some C) quiz questions Juha Nieminen <nospam@thanks.invalid> - 2022-05-16 11:21 +0000
Re: C++ (and some C) quiz questions Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-16 17:35 +0300
Re: C++ (and some C) quiz questions Juha Nieminen <nospam@thanks.invalid> - 2022-05-16 16:13 +0000
Re: C++ (and some C) quiz questions Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-16 10:49 -0700
Re: C++ (and some C) quiz questions Christian Gollwitzer <auriocus@gmx.de> - 2022-05-16 20:02 +0200
Re: C++ (and some C) quiz questions "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-05-16 20:51 +0200
Re: C++ (and some C) quiz questions Christian Gollwitzer <auriocus@gmx.de> - 2022-05-16 20:59 +0200
Re: C++ (and some C) quiz questions Manfred <noname@add.invalid> - 2022-05-16 21:55 +0200
Re: C++ (and some C) quiz questions Christian Gollwitzer <auriocus@gmx.de> - 2022-05-16 22:09 +0200
Re: C++ (and some C) quiz questions Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-16 13:47 -0700
Re: C++ (and some C) quiz questions Ben <ben.usenet@bsb.me.uk> - 2022-05-16 22:19 +0100
Re: C++ (and some C) quiz questions Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-05-16 14:52 -0700
Re: C++ (and some C) quiz questions Ben <ben.usenet@bsb.me.uk> - 2022-05-16 22:57 +0100
Re: C++ (and some C) quiz questions Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-17 00:54 +0300
Re: C++ (and some C) quiz questions Ben <ben.usenet@bsb.me.uk> - 2022-05-17 00:34 +0100
Re: C++ (and some C) quiz questions Christian Gollwitzer <auriocus@gmx.de> - 2022-05-17 08:24 +0200
Re: C++ (and some C) quiz questions Juha Nieminen <nospam@thanks.invalid> - 2022-05-17 08:21 +0000
Re: C++ (and some C) quiz questions Ben <ben.usenet@bsb.me.uk> - 2022-05-17 11:06 +0100
Re: C++ (and some C) quiz questions Juha Nieminen <nospam@thanks.invalid> - 2022-05-17 04:41 +0000
Re: C++ (and some C) quiz questions Ben <ben.usenet@bsb.me.uk> - 2022-05-17 11:12 +0100
Re: C++ (and some C) quiz questions Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-17 14:37 +0300
Re: C++ (and some C) quiz questions Ben <ben.usenet@bsb.me.uk> - 2022-05-17 14:31 +0100
Re: C++ (and some C) quiz questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-17 04:53 -0700
Re: C++ (and some C) quiz questions Juha Nieminen <nospam@thanks.invalid> - 2022-05-18 04:40 +0000
Re: C++ (and some C) quiz questions Manfred <noname@add.invalid> - 2022-05-18 13:29 +0200
Re: C++ (and some C) quiz questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-18 06:57 -0700
Re: C++ (and some C) quiz questions Paavo Helde <eesnimi@osa.pri.ee> - 2022-05-18 17:37 +0300
Re: C++ (and some C) quiz questions Juha Nieminen <nospam@thanks.invalid> - 2022-05-19 14:43 +0000
Re: C++ (and some C) quiz questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-19 08:21 -0700
Re: C++ (and some C) quiz questions Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-05-18 06:01 -0700
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