public member function
<unordered_set>

std::unordered_multiset::count

size_type count ( const key_type& k ) const;
Count elements with a specific key
Searches the container for elements with a value of k and returns the number of elements found.

Parameters

k
Value of the elements to be counted.
Member type key_type is the type of the elements in the container. In unordered_multiset containers it is the same as value_type, defined as an alias of the class's first template parameter (Key).

Return value

The number of elements in the container with a key equivalent to k.

Member type size_type is an unsigned integral type.

Example

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// unordered_multiset::count
#include <iostream>
#include <string>
#include <unordered_set>

int main ()
{
  std::unordered_multiset<std::string> myums =
    {"cow","pig","chicken","pig","pig","cow"};

  for (auto& x: {"cow","sheep","pig"}) {
    std::cout << x << ": " << myums.count(x) << std::endl;
  }

  return 0;
}


Output:
cow: 2
sheep: 0
pig: 3

Complexity

Average case: linear in the number of elements counted.
Worst case: linear in container size.

Iterator validity

No changes.

See also

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