C++ Deque operator

C++ Deque operator function is used to access the element at specified position pos. If position pos is greater than the size of container then it returns a value 0.

Difference between operator & at

When position pos is greater than the size of the container then operator function returns a value 0 while at function throws an exception i.e out of range.

Syntax

reference operator[] (int pos);

Parameter

pos : It defines the position of an element which is to be accessed.

Return value

It returns a reference to an element at position pos in the deque container.

Example 1

Let's see a simple example

#include <iostream>
#include<deque>
using namespace std;
int main()
{
   
  deque<string> a={"mango","is","my","favorite","fruit"};
   for(int i=0;i<a.size();i++)
  {
      cout<<a.operator[](i);
      cout<<" ";
  }
    return 0;
}

Output:

mango is my favorite fruit

In this example, operator function access each element of deque a.

Example 2

Let's see a simple example when pos is out of range.

#include <iostream>
#include<deque>
using namespace std;
int main()
{
     deque<int> a={1,2,3,4,5,6};
  
  cout<<a.operator[](7);
  return 0;
}

Output:

In this example, operator function tries to access the position which is greater than the size of the container. Therefore, it returns 0.