std::vector<T,Allocator>::size

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::vector<int>:

#include <vector>
#include <iostream>
 
int main()
{ 
    std::vector<int> nums {1, 3, 5, 7};
 
    std::cout << "nums contains " << nums.size() << " elements.\n";
}

Output:

nums contains 4 elements.

See also

returns the number of elements that can be held in currently allocated storage
(public member function)
checks whether the container is empty
(public member function)
returns the maximum possible number of elements
(public member function)
changes the number of elements stored
(public member function)

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/container/vector/size