std::flat_set<Key,Compare,KeyContainer>::count

 

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std::flat_set

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flat_set::flat_set flat_set::operator= Iterators flat_set::beginflat_set::cbegin flat_set::endflat_set::cend flat_set::rbeginflat_set::crbegin flat_set::rendflat_set::crend Capacity flat_set::size flat_set::max_size flat_set::empty Observers flat_set::key_comp flat_set::value_comp      Modifiers flat_set::clear flat_set::insert flat_set::insert_range flat_set::emplace flat_set::emplace_hint flat_set::erase flat_set::swap flat_set::extract flat_set::replace Lookup flat_set::count flat_set::find flat_set::contains flat_set::equal_range flat_set::lower_bound flat_set::upper_bound Non-member functions operator==operator<=> swap(std::flat_set) erase_if(std::flat_set)

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sorted_unique      sorted_unique_t

Deduction guides

 

size_type count( const Key& key ) const;	(1)	(since C++23)
template< class K > size_type count( const K& x ) const;	(2)	(since C++23)

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

1) Returns the number of elements with key key. This is either 1 or 0 since this container does not allow duplicates.

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. It allows 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, for overload (1), is either 1 or 0.

Complexity

Logarithmic in the size of the container plus linear in the number of 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)