std::unordered_set size() method

since C++11

// Const version only
size_type size() const noexcept;

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

Parameters

(none)

Return value

The number of elements in the container.

Complexity

Constant - O(1).

Exceptions

(none)

Example

Main.cpp

#include <unordered_set>
#include <iostream>
 
int main()
{ 
    std::unordered_set<int> nums {1, 3, 5, 7};
 
    std::cout << "nums contains " << nums.size() << " elements.\n";
}

Output

nums contains 4 elements.