Wrap-Up

Answers to Self Review Exercises

3.1	a) object. b) class. c) .h d) type, name. e) data member. f) access specifier. g) void. h) getline. i) binary scope resolution operator (::). j) #include.
3.2	a) False. By convention, function names begin with a lowercase letter and all subsequent words in the name begin with a capital letter. b) True. c) True. d) False. Such variables are called local variables and can be used only in the member function in which they are declared. e) True. f) True. g) True.
3.3	A local variable is declared in the body of a function and can be used only from the point at which it is declared to the immediately following closing brace. A data member is declared in a class definition, but not in the body of any of the class's member functions. Every object (instance) of a class has a separate copy of the class's data members. Also, data members are accessible to all member functions of the class.
3.4	A parameter represents additional information that a function requires to perform its task. Each parameter required by a function is specified in the function header. An argument is the value supplied in the function call. When the function is called, the argument value is passed into the function parameter so that the function can perform its task.

Exercises

3.5	Explain the difference between a function prototype and a function definition.
3.6	What is a default constructor? How are an object's data members initialized if a class has only an implicitly defined default constructor?
3.7	Explain the purpose of a data member.
3.8	What is a header file? What is a source-code file? Discuss the purpose of each.
3.9	Explain how a program could use class string without inserting a using declaration.
3.10	Explain why a class might provide a set function and a get function for a data member.
3.11	(Modifying Class GradeBook) Modify class GradeBook (Figs. 3.113.12) as follows: Include a second string data member that represents the course instructor's name. Provide a set function to change the instructor's name and a get function to retrieve it. Modify the constructor to specify two parametersone for the course name and one for the instructor's name. Modify member function displayMessage such that it first outputs the welcome message and course name, then outputs "This course is presented by: " followed by the instructor's name. Use your modified class in a test program that demonstrates the class's new capabilities.
3.12	(Account Class) Create a class called Account that a bank might use to represent customers' bank accounts. Your class should include one data member of type int to represent the account balance. [Note: In subsequent chapters, we'll use numbers that contain decimal points (e.g., 2.75)called floating-point valuesto represent dollar amounts.] Your class should provide a constructor that receives an initial balance and uses it to initialize the data member. The constructor should validate the initial balance to ensure that it is greater than or equal to 0. If not, the balance should be set to 0 and the constructor should display an error message, indicating that the initial balance was invalid. The class should provide three member functions. Member function credit should add an amount to the current balance. Member function debit should withdraw money from the Account and should ensure that the debit amount does not exceed the Account's balance. If it does, the balance should be left unchanged and the function should print a message indicating "Debit amount exceeded account balance." Member function getBalance should return the current balance. Create a program that creates two Account objects and tests the member functions of class Account.
3.13	(Invoice Class) Create a class called Invoice that a hardware store might use to represent an invoice for an item sold at the store. An Invoice should include four pieces of information as data membersa part number (type string), a part description (type string), a quantity of the item being purchased (type int) and a price per item (type int). [Note: In subsequent chapters, we'll use numbers that contain decimal points (e.g., 2.75)called floating-point valuesto represent dollar amounts.] Your class should have a constructor that initializes the four data members. Provide a set and a get function for each data member. In addition, provide a member function named getInvoiceAmount that calculates the invoice amount (i.e., multiplies the quantity by the price per item), then returns the amount as an int value. If the quantity is not positive, it should be set to 0. If the price per item is not positive, it should be set to 0. Write a test program that demonstrates class Invoice's capabilities.
3.14	(Employee Class) Create a class called Employee that includes three pieces of information as data membersa first name (type string), a last name (type string) and a monthly salary (type int). [Note: In subsequent chapters, we'll use numbers that contain decimal points (e.g., 2.75)called floating-point valuesto represent dollar amounts.] Your class should have a constructor that initializes the three data members. Provide a set and a get function for each data member. If the monthly salary is not positive, set it to 0. Write a test program that demonstrates class Employee's capabilities. Create two Employee objects and display each object's yearly salary. Then give each Employee a 10 percent raise and display each Employee's yearly salary again.
3.15	(Date Class) Create a class called Date that includes three pieces of information as data membersa month (type int), a day (type int) and a year (type int). Your class should have a constructor with three parameters that uses the parameters to initialize the three data members. For the purpose of this exercise, assume that the values provided for the year and day are correct, but ensure that the month value is in the range 112; if it is not, set the month to 1. Provide a set and a get function for each data member. Provide a member function displayDate that displays the month, day and year separated by forward slashes (/). Write a test program that demonstrates class Date's capabilities.