std::map<Key,T,Compare,Allocator>:: size

From cppreference.com

C++
Containers library
std::map
Member functions
Non-member functions
(until C++20) (until C++20) (until C++20) (until C++20) (until C++20)
Deduction guides (C++17)
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

Run this code 
#include <cassert>
#include <map>
 
int main()
{
    std::map<int, char> nums{{1, 'a'}, {1, 'b'}, {2, 'c'}, {2, 'd'}};
    assert(nums.size() == 2); 
}

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)
Retrieved from " https://en.cppreference.com/mwiki/index.php?title=cpp/container/map/size&oldid=135932 "