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std::unordered_map<Key,T,Hash,KeyEqual,Allocator>::size

From cppreference.com
 
 
 
 
size_type size() const noexcept;
(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] Complexity

Constant.

[edit] Example

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

#include <iostream>
#include <unordered_map>
 
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) [edit]
returns the maximum possible number of elements
(public member function) [edit]
(C++17)(C++20)
returns the size of a container or array
(function template) [edit]