Data Structures, Algorithms, & Applications in C+
Chapter 1, Exercise 17

We have at least two options on how to proceed. The new functions can be placed directly into the class currency or we can place the new functions in a class enhancedCurrency which is derived from currency. We shall take the former approach. The code for the new functions is given below as well as in the file enhancedCurrencyNew.h.

void input()
{
   // input the amount as a double
   cout << "Enter the currency amount as a real number" << endl;
   double theValue;
   cin >> theValue;
   
   // set the value
   setValue(theValue);
}
   
currency subtract(const currency& x)
{// Return *this - x.
   currency result;
   result.amount = amount - x.amount;
   return result;
}
   
currency percent(float x)
{// Return x percent of *this.
   currency result;
   result.amount = (long) (amount * x / 100);
   return result;
}
   
currency multiply(float x)
{// Return this * x.
   currency result;
   result.amount = (long) (amount * x);
   return result;
}
   
currency divide(float x)
{// Return this / x.
   currency result;
   result.amount = (long) (amount / x);
   return result;
}