std::unordered_multiset<Key,Hash,KeyEqual,Allocator>::count
From cppreference.com
< cpp | container | unordered multiset
size_type count( const Key& key ) const; |
(1) | (since C++11) |
size_type count( const Key& key, std::size_t hash ) const; |
(1) | (since C++20) |
template< class K > size_type count( const K& x ) const; |
(2) | (since C++20) |
template< class K > size_type count( const K& x, std::size_t hash ) const; |
(2) | (since C++20) |
1) Returns the number of elements with key that compares equal to the specified argument
key
.2) Returns the number of elements with key that compares equivalent to the specified argument
x
. This overload only participates in overload resolution if the qualified-id Hash::transparent_key_equal is valid and denotes a type. This assumes that such Hash is callable with both K and Key type, and that its key_equal is transparent, which, together, allows calling this function without constructing an instance of Key
.
If present, the |
(since C++20) |
Parameters
key | - | key value of the elements to count |
x | - | a value of any type that can be transparently compared with a key |
hash | - | the hash value of the key |
Return value
1) Number of elements with key
key
.2) Number of elements with key that compares equivalent to
x
.Complexity
linear in the number of elements with key key
on average, worst case linear in the size of the container.
See also
finds element with specific key (public member function) | |
returns range of elements matching a specific key (public member function) |