Chapter 9 - Classes: A Deeper Look, Part 1

• 9.2 Time Class Case Study
  • Time class definition
    • Use #ifndef, #define and #endif preprocessor directives to form a preprocessor warpper that prevents headers from being included more than once in a program.
  • Time class member function implementation
    • The throw statement (lines 28-29) creates a new object of type invalid_argument.
    • setfill is a "sticky" setting. Once the fill character is specified, it applies for all subsequent values.
  • Program to test class Time
    • 中文說 "下午1點27分", 英文則是 "1:27PM".
• 9.3 Class Scope and Accessing Class Members
  • Accessing an object's member through (1) the object's name, (2) a reference to the object and (3) a pointer to the object.
• 9.5 Access Functions and Utility Functions
  • SalesPerson class definition
    • The private member function "totalAnualSales()" is a utility function (helper function) for printAnnualSales().
  • SalesPerson class member-function implementation
  • Utility fucntion demonstration
• 9.6 Constructors with Default Arguments
  • Time class containing a constructor with default arguments
    • P.263 Default value of an argument must be specified with the first occurrence of the function name -- typically, in the function prototype.
  • Time class member-function implementation
  • Calling the constructor with 0 argument, 1 argument, 2 arguments, 3 arguments, and 3 invalid arguments.
• 9.7 Destructors
  • CreateAndDestroy class definition
    • The name of the destructor is a tilde character (~) followed by the class name.
  • CreateAndDestroy class member-function implementation
    • The destructor shows a message so that we can see when a destructor is invoked.
  • Order in which constructors and destructors are called
    1. Objects in Global Scope:
       • Constructors called before any function (including main).
    2. Local Automatic Objects
    3. static Local Objects
• 9.9 Dangerous to Return a Reference to a private Data Member
  • Time class declaration
    • The function badSetHour() returns a reference.
  • Time class member-function implementation
    • Bad practice: Returing a refernece to a private data member
  • fig09_16.cpp
    • With a reference, the client can bypass the validating defined in the object member functions, and modify the value of that private data member arbitrarily.
• 9.10 Default Memberwise Assignment
  • Date class declaration
  • Date class member-function definitions
  • Default memberwise assignment