# std::unordered_map::count

 size_type count( const Key& key ) const; (1) (since C++11)

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

## Contents

### Parameters

 key - key value of the elements to count

### Return value

Number of elements with key key, that is either 1 or 0.

### Complexity

Constant on average, worst case linear in the size of the container.