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std::map::size

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< cpp‎ | container‎ | map
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size_type size() const;

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] Exceptions

(none) (until C++11)
noexcept specification:  
noexcept
  
(since C++11)

[edit] Complexity

Constant.

[edit] Example

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

#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.

[edit] See also

checks whether the container is empty
(public member function) [edit]
returns the maximum possible number of elements
(public member function) [edit]