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Difference between revisions of "cpp/container/unordered multimap/emplace hint"

From cppreference.com
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{{cpp/container/unordered_multimap/title|emplace_hint}}
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{{include page|cpp/container/emplace_hint|unordered_multimap}}
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{{dcl begin}}
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{{dcl|since=c++11|
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template< class... Args >
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iterator emplace_hint( const_iterator hint, Args&&... args );
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}}
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{{dcl end}}
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Inserts a new element to the container, using {{c|hint}} as a suggestion where the element should go. The element is constructed in-place, i.e. no copy or move operations are performed.
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The constructor of the element type ({{tt|value_type}}, that is, {{c|std::pair<const Key, T>}}) is called with exactly the same arguments as supplied to the function, forwarded with {{c|std::forward<Args>(args)...}}.
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{{cpp/container/note_iterator_invalidation|unordered_multimap|emplace_hint}}
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===Parameters===
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{{par begin}}
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{{par|hint|iterator, used as a suggestion as to where to insert the new element}}
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{{par|args|arguments to forward to the constructor of the element}}
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{{par end}}
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===Return value===
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Returns an iterator to the newly inserted element.
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===Exceptions===
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If an exception is thrown by any operation, this function has no effect (strong exception guarantee).
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===Complexity===
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Amortized constant on average, worst case linear in the size of the container.
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===See also===
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{{dsc begin}}
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{{dsc inc|cpp/container/dsc emplace|unordered_multimap}}
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{{dsc inc|cpp/container/dsc insert|unordered_multimap}}
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{{dsc end}}
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{{langlinks|de|es|fr|it|ja|pt|ru|zh}}
 
{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Latest revision as of 08:04, 30 January 2024

[edit template]
 
C++
 
Containers library
 
std::unordered_multimap
Member types
Member functions
Non-member functions
(until C++20)
Deduction guides (C++17)
 
template< class... Args >
iterator emplace_hint( const_iterator hint, Args&&... args );
 (since C++11)

Inserts a new element into the container, using hint as a suggestion where the element should go.

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 after the operation the new number of elements is greater than old max_load_factor() * bucket_count() a rehashing takes place.
If rehashing occurs (due to the insertion), all iterators are invalidated. Otherwise (no rehashing), iterators are not invalidated.

Contents

[edit] 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

[edit] Return value

An iterator to the inserted element.

[edit] Exceptions

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

[edit] Complexity

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

[edit] Example

This section is incomplete
Reason: no example

[edit] See also

 constructs element in-place
(public member function) [edit]
inserts elements or nodes(since C++17)
(public member function) [edit]
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