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

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< cpp‎ | container‎ | unordered map

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::unordered_map:

Run this code

    #include <unordered_map>
    #include <iostream>

    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.

### See also

empty (C++11) | checks whether the container is empty (public member function)
max_size (C++11) | returns the maximum possible number of elements (public member function)
size ssize (C++17)(C++20) | returns the size of a container or array (function template)

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