#include <iostream>
#include <string>

using namespace std;

int main( )
{
   string credit_card( "4578 9906 512 6661" );
   cout << "Credit card number: " << credit_card;

   // equivalent of strnset()
   credit_card.replace( 0, credit_card.length()-4,credit_card.length()-4, '*' );
   cout << "\nSecure display of credit card number: " << credit_card;

}
