C++ Deque size

C++ Deque size function determines the number of elements present in the deque container.

For example:

deque<int> d={1,2,3,4,5};
                        d.size()=5;

Syntax

return_type size();

where , return_type is an unsigned integral type.

Parameter

It does not contain any parameter.

Return value

It returns the number of elements in the deque container.

Example

Let's see a simple example

#include <iostream>
#include<deque>
using namespace std;
int main()
{
  deque<int> d;
  cout<<"size of deque is :"<<d.size();
  cout<<'\n';
  d.push_back(1);
  d.push_back(2);
  d.push_back(3);
  cout<<"size of deque is :"<<d.size();
   return 0;
}

Output:

size of deque is :0
size of deque is :3

In this example, when deque 'd' is empty then the size function returns 0. When three elements are added in the deque container then size function returns 3.