Sams Teach Yourself C++ in 21 Days

Understanding Object-Oriented Programming 151

6

22: // definition of SetAge, public

23: // accessor function

24: // sets itsAge member

25: void Cat::SetAge(int age)

26: {

27: // set member variable itsAge to

28: // value passed in by parameter age

29: itsAge = age;

30: }

31:

32: // definition of Meow method

33: // returns: void

34: // parameters: None

35: // action: Prints “meow” to screen

36: void Cat::Meow()

37: {

38: std::cout << “Meow.\n”;

39: }

40:

41: // create a cat, set its age, have it

42: // meow, tell us its age, then meow again.

43: int main()

44: {

45: Cat Frisky;

46: Frisky.SetAge(5);

47: Frisky.Meow();

48: std::cout << “Frisky is a cat who is “ ;

49: std::cout << Frisky.GetAge() << “ years old.\n”;

50: Frisky.Meow();

51: return 0;

52: }

Meow.

Frisky is a cat who is 5 years old.

Meow.

Lines 5–13 contain the definition of the Catclass. Line 7 contains the keyword

public, which tells the compiler that what follows is a set of public members.

Line 8 has the declaration of the public accessor method GetAge(). GetAge()provides

access to the private member variable itsAge, which is declared on line 12. Line 9 has

the public accessor functionSetAge(). SetAge()takes an integer as an argument and

sets itsAgeto the value of that argument.

Line 10 has the declaration of the class method Meow().Meow()is not an accessor func-

tion. Here it is a general method that prints the word “Meow” to the screen.

OUTPUT

LISTING6.3 continued

ANALYSIS