std::set<Key,Compare,Allocator>::size

< cpp‎ | container‎ | set

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

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.

Example

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

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

Output:

nums contains 4 elements.

See also

 checks whether the container is empty
(public member function)
returns the maximum possible number of elements
(public member function)
(C++17)(C++20)
 returns the size of a container or array
(function template)