std::unordered_map::size

From cppreference.com

size_type size() const;
(since C++11)

Returns the number of elements in the container, i.e. std::distance(begin(), end()).

Contents

[edit] Parameters

(none)

[edit] Return value

the number of elements in the container

[edit] Exceptions

noexcept specification:  
noexcept
  (since C++11)

[edit] Complexity

Constant

[edit] Example

The following code uses size to display the number of elements in a std::unordered_map<int>:

#include <unordered_map>
#include <iostream>
 
int main()
{
    std::unordered_map<int, char> nums {{1, 'a'}, {3, 'b'}, {5, 'c'}, {7, 'd'}};
 
    std::cout << "nums contains " << nums.size() << " elements.\n";
}

Output:

nums contains 4 elements.

[edit] See also

checks whether the container is empty
(public member function)
returns the maximum possible number of elements
(public member function)