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Groups > comp.lang.c++ > #123725
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: Move semantics with literals |
| Date | 2026-04-14 17:26 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <10rlmc0$5jbr$1@dont-email.me> (permalink) |
| References | <10rlkk9$6hau$1@dont-email.me> <87jyu960xp.fsf@posteo.de> <87fr4x60ig.fsf@posteo.de> |
On 14/04/2026 17:10, Jonathan Lamothe wrote:
> Jonathan Lamothe <jonathan@jlamothe.net> writes:
>
>> boltar@caprica.universe writes:
>>
>>> To my chagrin I got caught out by this trick question in an interview:
>>>
>>> int func(int &&a)
>>> {
>>> return a * 2;
>>> }
>>>
>>>
>>> :
>>> int b = func(123);
>>> :
>>>
>>> Where the question was "what would happen". I assumed it wouldn't compile
>>> being a reference to a literal but it does. So I'm just wondering why on
>>> earth and when would you ever do the above? Is there some wierd use case?
>>
>> The only use case I can see is tricky interview questions. ;)
>
> More seriously though, I'm not sure off-hand, but this feels like a case
> of undefined behaviour. At any rate, it's terrible for the clarity of
> the code, which I try to prioritize.
>
As far as I understand it, it is fully defined behaviour. The value 123
is a temporary, and exists until the expression containing it is fully
evaluated. (If I am wrong here, hopefully someone will correct me!)
rvalue references are not much use for simple types like "int". They
become useful with bigger types. But it would be very strange for the
standards to say you could /only/ use them for big types.
> I hate it when job interview questions don't actually reflect the kind
> of work you'll be expected to do. Though, if this *is* the
> expectation... bullet dodged, I guess?
>
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Move semantics with literals boltar@caprica.universe - 2026-04-14 14:57 +0000
Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 11:01 -0400
Re: Move semantics with literals wij <wyniijj5@gmail.com> - 2026-04-14 23:04 +0800
Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 11:10 -0400
Re: Move semantics with literals David Brown <david.brown@hesbynett.no> - 2026-04-14 17:26 +0200
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-14 18:25 +0200
Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 13:02 -0400
Re: Move semantics with literals boltar@caprica.universe - 2026-04-15 08:18 +0000
Re: Move semantics with literals Paavo Helde <eesnimi@osa.pri.ee> - 2026-04-15 12:50 +0300
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-15 14:24 +0200
Re: Move semantics with literals boltar@caprica.universe - 2026-04-15 15:07 +0000
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-15 17:49 +0200
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-15 17:51 +0200
Re: Move semantics with literals boltar@caprica.universe - 2026-04-16 08:29 +0000
Re: Move semantics with literals scott@slp53.sl.home (Scott Lurndal) - 2026-04-16 14:41 +0000
Re: Move semantics with literals Chris Ahlstrom <OFeem1987@teleworm.us> - 2026-04-18 06:41 -0400
Re: Move semantics with literals Richard Damon <Richard@Damon-Family.org> - 2026-04-18 12:46 -0400
Re: Move semantics with literals "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-15 23:08 -0700
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-16 09:02 +0200
Re: Move semantics with literals "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2026-04-16 04:39 -0700
Re: Move semantics with literals boltar@caprica.universe - 2026-04-14 15:10 +0000
Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 11:15 -0400
Re: Move semantics with literals scott@slp53.sl.home (Scott Lurndal) - 2026-04-14 17:17 +0000
Re: Move semantics with literals Jonathan Lamothe <jonathan@jlamothe.net> - 2026-04-14 13:36 -0400
Re: Move semantics with literals boltar@caprica.universe - 2026-04-15 08:21 +0000
Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-18 10:16 -0700
Re: Move semantics with literals boltar@caprica.universe - 2026-04-19 08:59 +0000
Re: Move semantics with literals boltar@caprica.universe - 2026-04-19 09:09 +0000
Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-19 12:01 -0700
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-14 17:14 +0200
Re: Move semantics with literals boltar@caprica.universe - 2026-04-14 15:23 +0000
Re: Move semantics with literals Bonita Montero <Bonita.Montero@gmail.com> - 2026-04-14 18:23 +0200
Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-18 09:27 -0700
Re: Move semantics with literals Andrey Tarasevich <noone@noone.net> - 2026-04-18 09:46 -0700
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