std::set::emplace

 

C++

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Technical Specifications

 

Containers library

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Capacity

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Modifiers

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Observers

set::key_comp

set::value_comp

 

template< class... Args > std::pair<iterator,bool> emplace( Args&&... args );		(since C++11)

Inserts a new element into the container by constructing it in-place with the given args if there is no element with the key in the container.

Careful use of emplace allows the new element to be constructed while avoiding unnecessary copy or move operations. The constructor of the new element is called with exactly the same arguments as supplied to emplace, forwarded via std::forward<Args>(args)....

No iterators or references are invalidated.

Parameters

args

-

arguments to forward to the constructor of the element

Return value

Returns a pair consisting of an iterator to the inserted element, or the already-existing element if no insertion happened, and a bool denoting whether the insertion took place.

Exceptions

If an exception is thrown by any operation, this function has no effect.

Complexity

Logarithmic in the size of the container.

See also

emplace_hint (C++11)	constructs elements in-place using a hint (public member function)
insert	inserts elements (public member function)