Chapter 20, Problem 20.12E

(Payroll System Modification) Modify the payroll system of Figs20.9.— 20.17 to include private data member birthDate in class Employee. Use class Date from Figs18.6.—18.7 to represent an employee’s birthday. Assume that payroll is processed once per month. Create a vector of Employee references to store the various employee objects. In a loop, calculate the payroll for each Employee (polymorphically), and add a $100.00 bonus to the person’s payroll amount if the current month is the month in which the Employee’s birthday occurs.