REVIEW EXERCISES. Draw an inheritance diagram that shows the relationships between these classes.

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1 Review Exercises A derived-class pointer can be converted to a base-class pointer. 12. When a virtual function is called, the version belonging to the actual type of the implicit parameter is invoked. 13. A dynamically bound function is selected at run time. A statically bound function is selected at compile time. REVIEW EXERCISES Exercise R8.1. An object-oriented traffic simulation system has the following classes: Vehicle Car Truck Sedan Coupe PickupTruck SportUtilityVehicle Minivan Bicycle Motorcycle Draw an inheritance diagram that shows the relationships between these classes. Exercise R8.2. What inheritance relationships would you establish among the following classes? Student Professor TeachingAssistant Employee Secretary DepartmentChair Janitor SeminarSpeaker Person Course Seminar Lecture ComputerLab Exercise R8.3. Consider the following classes B and D: B(); B(int n); ; B::B() cout << "B::B()\n"; B::B(int n)

2 368 CHAPTER 8 Inheritance cout << "B::B(" << n << ")\n"; D(); D(int n); private: B b; ; D::D() cout << "D::D()\n"; D::D(int n) : B(n) b = B(-n); cout << "D::D("<< n <<")\n"; What does the following program print? int main() D d(3); return 0; Determine the answer by hand, not by compiling and running the program. Exercise R8.4. What does the following program print? void print(int n) const; ; void B::print(int n) const cout << n << "\n"; void print(int n) const; ; void D::print(int n) const if (n <= 1) B::print(n); else if (n % 2 == 0) print(n / 2); else print(3 * n + 1);

3 Review Exercises 369 int main() D d; d.print(3); return 0; Determine the answer by hand, not by compiling and running the program. Exercise R8.5. What is wrong with the following code? B(); B(int n); void print() const; private: int b; ; B::B() b = 0; B::B(int n) b = n; void B::print() const cout << "B: " << b << "\n"; D(); D(int n); void print() const; ; D::D() D::D(int n) b = n;

4 370 CHAPTER 8 Inheritance void D::print() const cout << "D: " << b << "\n"; How can you fix the errors? Exercise R8.6. Suppose the class D inherits from B. Which of the following assignments are legal? B b; D d; B* pb; D* pd; a. b = d; b. d = b; c. pd = pb; d. pb = pd; e. d = pd; f. b = *pd; g. *pd = *pb; Exercise R8.7. Which of the following calls are statically bound, and which are dynamically bound? What does the program print? B(); virtual void p() const; void q() const; ; B::B() void B::p() const cout << "B::p\n"; void B::q() const cout << "B::q\n"; D(); virtual void p() const; void q() const; ;

5 Review Exercises 371 D::D() void D::p() const cout << "D::p\n"; void D::q() const cout << "D::q\n"; int main() B b; D d; B* pb = new B; B* pd = new D; D* pd2 = new D; b.p(); b.q(); d.p(); d.q(); pb->p(); pb->q(); pd->p(); pd->q(); pd2->p(); pd2->q(); return 0; Determine the answer by hand, not by compiling and running the program. Exercise R8.8. True or false? a. When a member function is invoked through a pointer, it is always statically bound. b. When a member function is invoked through an object, it is always statically bound. c. Only member functions can be dynamically bound. d. Only nonmember functions can be statically bound. e. When a function is virtual in the base class, it cannot be made nonvirtual in a derived class. f. Calling a virtual function is slower than calling a nonvirtual function. g. Constructors can be virtual. h. It is good programming practice to make all member functions virtual.

6 372 CHAPTER 8 Inheritance PROGRAMMING EXERCISES Exercise P8.1. Derive a class Programmer from Employee. Supply a constructor Programmer(string name, double salary) that calls the base-class constructor. Supply a function get_name that returns the name in the format "Hacker, Harry (Programmer)". Exercise P8.2. Implement a base class Person. Derive classes Student and Instructor from Person. A person has a name and a birthday. A student has a major, and an instructor has a salary. Write the class definitions, the constructors, and the member functions print() for all classes. Exercise P8.3. Derive a class Manager from Employee. Add a data field, named department, of type string. Supply a function print that prints the manager s name, department, and salary. Derive a class Executive from Manager. Supply a function print that prints the string Executive, followed by the information stored in the Manager base object. Exercise P8.4. Implement a base class Account and derived classes Savings and Checking. In the base class, supply member functions deposit and withdraw. Provide a function daily_interest that computes and adds the daily interest. For calculations, assume that every month has 30 days. Checking accounts yield interest of 3 percent monthly on balances over $1,000. Savings accounts yield interest of 6 percent on the entire balance. Write a driver program that makes a month s worth of deposits and withdrawals and calculates the interest every day. Exercise P8.5. Measure the speed difference between a statically bound call and a dynamically bound call. Use the Time class to measure the time spent in one loop of virtual function calls and another loop of regular function calls. Exercise P8.6. Write a base class Worker and derived classes HourlyWorker and SalariedWorker. Every worker has a name and a salary rate. Write a virtual function compute_pay(int hours) that computes the weekly pay for every worker. An hourly worker gets paid the hourly wage for the actual number of hours worked, if hours is at most 40. If the hourly worker worked more than 40 hours, the excess is paid at time and a half. The salaried worker gets paid the hourly wage for 40 hours, no matter what the actual number of hours is. Exercise P8.7. Implement a base class Appointment and derived classes Onetime, Daily, Weekly, and Monthly. An appointment has a description (for example, see the dentist ) and a date and time. Write a virtual function occurs_on(int year, int month, int day) that checks whether the appointment occurs on that date. For example, for a monthly appointment, you must check whether the day of the month matches. Then fill a vector of Appointment* with a mixture of appointments. Have the user enter a date and print out all appointments that happen on that date. Exercise P8.8. Improve the appointment book program of Exercise P8.7. Give the user the option to add new appointments. The user must specify the type of the appointment, the description, and the date and time.