std::multimap<Key,T,Compare,Allocator>::count

 

C++

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Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

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Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

Views

span (C++20)

 

std::multimap

Member functions

multimap::multimap

multimap::~multimap

multimap::operator=

multimap::get_allocator

Iterators

multimap::beginmultimap::cbegin (C++11)

multimap::endmultimap::cend (C++11)

multimap::rbeginmultimap::crbegin (C++11)

multimap::rendmultimap::crend (C++11)

Capacity

multimap::empty

multimap::size

multimap::max_size

Modifiers

multimap::clear

multimap::insert

multimap::emplace (C++11)

multimap::emplace_hint (C++11)

multimap::erase

multimap::swap

multimap::extract (C++17)

multimap::merge (C++17)

Lookup

multimap::count

multimap::find

multimap::contains (C++20)

multimap::equal_range

multimap::lower_bound

multimap::upper_bound

Observers

multimap::key_comp

multimap::value_comp

Non-member functions

std::swap

erase_if (C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides(C++17)

 

size_type count( const Key& key ) const;	(1)
template< class K > size_type count( const K& x ) const;	(2)	(since C++14)

Returns the number of elements with key that compares equivalent to the specified argument.

1) Returns the number of elements with key key.

2) Returns the number of elements with key that compares equivalent to the value x. This overload participates in overload resolution only if the qualified-id Compare::is_transparent is valid and denotes a type. They allow calling this function without constructing an instance of Key.

Parameters

key	-	key value of the elements to count
x	-	alternative value to compare to the keys

Return value

Number of elements with key that compares equivalent to key or x.

Complexity

Logarithmic in the size of the container plus linear in the number of the elements found.

See also

find	finds element with specific key (public member function)
equal_range	returns range of elements matching a specific key (public member function)