NAME¶

std::map::size - std::map::size

Synopsis¶

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::map:

// Run this code

#include <map>
#include <iostream>

int main()
{
std::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.

See also¶

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