NAME¶

std::unordered_map::emplace_hint - std::unordered_map::emplace_hint

Synopsis¶

template <class... Args> (since C++11)
iterator emplace_hint( const_iterator hint, Args&&... args );

Inserts a new element to the container, using hint as a suggestion where the element
should go. The element is constructed in-place, i.e. no copy or move operations are
performed.

The constructor of the element type (value_type, that is, std::pair<const Key, T>)
is called with exactly the same arguments as supplied to the function, forwarded
with std::forward<Args>(args)....

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 greater than max_load_factor()*bucket_count().

Parameters¶

hint - iterator, used as a suggestion as to where to insert the new element
args - arguments to forward to the constructor of the element

Return value¶

Returns an iterator to the newly inserted element.

If the insertion failed because the element already exists, returns an iterator to
the already existing element with the equivalent key.

Exceptions¶

If an exception is thrown by any operation, this function has no effect (strong
exception guarantee).

Complexity¶

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

See also¶

emplace constructs element in-place
(C++11) (public member function)
inserts elements
insert or nodes
(C++11) (since C++17)
(public member function)