[] operator Overloading

//[] operator Overloading
#include <iostream.h>
#include <process.h>
class matrix
{
private:
     int mat[4];
public:

     matrix()
     {
        mat[0]=1;
        mat[1]=2;
        mat[2]=3;
        mat[3]=4;
     }


     int operator[](int index)
     {
         if(index>=0&&index<=3)
            return mat[index];
         else
            {
            cout<<"Index Out of Array Limits!";
            exit(0);
            }
     }
};

int main()
{
    matrix m;
    cout<<"\nSafe Array Access:\nm[0]= "<<m[0]<<endl<<"m[1]= "<<m[1]<<endl<<"m[2]= "<<m[2]<<endl<<"m[3]= "<<m[3]<<endl;
    cout<<"\nUnsafe Access:\n";
    cout<<"m[5]= ";
    cout<<m[5];
    return 0;
}