Class T{ public: T(int n){

Copy elision is avoiding unnecessary copy and move. There used to be issues when there was no guaranteed copy elision. For example, T t = f(); This type of expression would create a temporary which would be copied before C++11 afaik. Then later C++ standards gave you the ability to extend the lifetime of the temporaries for the sake of moving them. Now with guaranteed copy elision, the object is constructed in place rather than creating an unnecessarily copy

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11 месяцев назад

Ujjawal Gupta Автор вопроса

So it's only an explicit call?

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11 месяцев назад

Manav | avoid unnecessary messaging me

Ujjawal Gupta
So it's only an explicit call?

What do you mean by that?

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11 месяцев назад

Ujjawal Gupta Автор вопроса

Manav | avoid unnecessary messaging me
What do you mean by that?

Here they said that calls like vector(2) are explicit (page: 643)

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11 месяцев назад

Manav | avoid unnecessary messaging me

Okay, I misunderstood what you meant to ask T{5}, can invoke the copy constructor but this can be elided. Gimme a moment so I can read the specific passage. Don't forget to specify the name of the book when you're asking here. It may be obvious to me that you're referring to Programming:Practice and principles using C++ by Bjarne Stroustup but it's not to other members.

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11 месяцев назад

Manav | avoid unnecessary messaging me

Ujjawal Gupta

Here they said that calls like vector(2) are expli...

Here Bjarne is talking about implicit and explicit conversions. As for your question, T{5} will call the T(int) constructor directly so there's no disambiguity there.

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11 месяцев назад

Ujjawal Gupta Автор вопроса

Manav | avoid unnecessary messaging me
Here Bjarne is talking about implicit and explicit...

it's an explicit call only?

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11 месяцев назад

Manav | avoid unnecessary messaging me

Ujjawal Gupta
it's an explicit call only?

I would say yes T{5} is you doing an explicit conversion, like T(5) T t = 5; This would be an implicit conversion

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11 месяцев назад

Ujjawal Gupta Автор вопроса

Manav | avoid unnecessary messaging me
I would say yes T{5} is you doing an explicit conv...

Got it

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11 месяцев назад

Manav | avoid unnecessary messaging me

Manav | avoid unnecessary messaging me
Okay, I misunderstood what you meant to ask T{5},...

As for what I meant by eliding the copy construction T t = T{5}; The copy construction here will be elided. There will be only one call to T(int), you won't see T(T&)

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11 месяцев назад

Ujjawal Gupta Автор вопроса

Manav | avoid unnecessary messaging me
As for what I meant by eliding the copy constructi...

Is it copy elision?

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11 месяцев назад

Manav | avoid unnecessary messaging me

Ujjawal Gupta
Is it copy elision?

Yep

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11 месяцев назад