std::unordered_map::emplace

 

C++

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Containers library

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std::unordered_map

Member functions

unordered_map::unordered_map

unordered_map::~unordered_map

unordered_map::operator=

unordered_map::get_allocator

Iterators

unordered_map::begin unordered_map::cbegin

unordered_map::end unordered_map::cend

Capacity

unordered_map::erase

unordered_map::size

unordered_map::max_size

Modifiers

unordered_map::clear

unordered_map::insert

unordered_map::emplace

unordered_map::emplace_hint

unordered_map::erase

unordered_map::swap

Lookup

unordered_map::count

unordered_map::find

unordered_map::equal_range

Bucket interface

unordered_map::begin(int)

unordered_map::end(int)

unordered_map::bucket_count

unordered_map::max_bucket_count

unordered_map::bucket_size

unordered_map::bucket

Hash policy

unordered_map::load_factor

unordered_map::max_load_factor

unordered_map::rehash

unordered_map::reserve

Observers

unordered_map::hash_function

unordered_map::key_eq

 

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

Inserts a new element to the container. The element is constructed in-place, i.e. no copy or move operations are performed. The constructor of the element type (value_type) is called as follows: the first argument is used to construct the key, the rest of the arguments are used to construct the value.

If rehashing occurs due to the insertion, all iterators are invalidated. Otherwise iterators are not affected. References are not invalidated. Rehashing occurs only if the new number of elements is higher than max_load_factor()*bucket_count().

Parameters

args

-

arguments to forward to the constructor of the element

Return value

returns a pair consisting of a bool denoting whether the insertion took place and an iterator to the inserted element.

Complexity

Amortized constant on average, worst case linear in the size of the container.

See also

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