Subscripting [] Operator Overloading in C++

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The subscript operator [] is normally used to access array elements. This operator can be overloaded to enhance the existing functionality of C++ arrays.

Following example explains how a subscript operator [] can be overloaded.

#include <iostream>
using namespace std;
const int SIZE = 10;

class safearay {
   private:
      int arr[SIZE];
      
   public:
      safearay() {
         register int i;
         for(i = 0; i < SIZE; i++) {
           arr[i] = i;
         }
      }
      
      int &operator[](int i) {
         if( i > SIZE ) {
            cout << "Index out of bounds" <<endl; 
            // return first element.
            return arr[0];
         }
         
         return arr[i];
      }
};

int main() {
   safearay A;

   cout << "Value of A[2] : " << A[2] <<endl;
   cout << "Value of A[5] : " << A[5]<<endl;
   cout << "Value of A[12] : " << A[12]<<endl;

   return 0;
}

When the above code is compiled and executed, it produces the following result −

Value of A[2] : 2
Value of A[5] : 5
Index out of bounds
Value of A[12] : 0