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std::map count() method

// (1) Const version only
size_type count( const Key& key ) const;

// (2) Const version only
template< class K >
size_type count( const K& x ) const;

Returns the number of elements with key that compares equivalent to the specified argument, which is either 1 or 0 since this container does not allow duplicates.

  • (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, which is either 1 or 0 for (1).

Complexity​

Logarithmic in the size of the container - O(log size()).

Exceptions​

(none)

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std::map count() method

// (1) Const version only
size_type count( const Key& key ) const;

// (2) Const version only
template< class K >
size_type count( const K& x ) const;

Returns the number of elements with key that compares equivalent to the specified argument, which is either 1 or 0 since this container does not allow duplicates.

  • (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, which is either 1 or 0 for (1).

Complexity​

Logarithmic in the size of the container - O(log size()).

Exceptions​

(none)

This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.