Case Study: Payroll System Using Polymorphism

• Base class Employee
  • Pure virtual function earnings (returns pay)
    • Pure virtual because need to know employee type
    • Cannot calculate for generic employee
  • Other classes derive from Employee

  Figure 14: Class hierarchy for the polymorphic employee-payroll application.

  
• Downcasting
  • dynamic_cast operator
    • Determine object's type at runtime
    • Returns 0 if not of proper type (cannot be cast)
    • NewClass *ptr = dynamic_cast < NewClass *> objectPtr;
• Keyword typeid
  • Header <typeinfo>
  • Usage: typeid(object)
    • Returns type_info object
    • Has information about type of operand, including name
    • typeid(object).name()

Figure 15: Employee class header file.

Figure 16: Employee class implementation file. (part 1 of 2)

Figure 17: Employee class implementation file (part 2 of 2) and SalariedEmployee class header file.

Figure 18: SalariedEmployee class implementation file.

Figure 19: HourlyEmployee class header file.

Figure 20: HourlyEmployee class implementation file.

Figure 21: CommissionEmployee class header file.

Figure 22: CommissionEmployee class implementation file.

Figure 23: BasePlusCommissionEmployee class header file.

Figure 24: BasePlusCommissionEmployee class implementation file.

Figure 25: Employee class hierarchy driver program.(part 1 of 2)

Figure 26: Employee class hierarchy driver program.(part 2 of 2)