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