Sams Teach Yourself C++ in 21 Days

9: void SetAge(unsigned int Age);

10:

11: unsigned int GetWeight();

12: void SetWeight(unsigned int Weight);

13:

14: // public member functions

15: void Meow();

16:

17: // private member data

18: private:

19: unsigned int itsAge;

20: unsigned int itsWeight;

21: };

This class has five public methods. Lines 8 and 9 contain the accessor methods

for itsAge. You can see that on line 8 there is a method for getting the age and

on line 9 there is one for setting it. Lines 11 and 12 contain similar accessor methods for

itsWeight. These accessor functions set the member variables and return their values.

The public member function Meow()is declared on line 15. Meow()is not an accessor

function. It doesn’t get or set a member variable; it performs another service for the

class, printing the word “Meow.”

The member variables themselves are declared on lines 19 and 20.

To set Frisky’s age, you would pass the value to the SetAge()method, as in

Cat Frisky;

Frisky.SetAge(5); // set Frisky’s age using the public accessor

Later today, you’ll see the specific code for making the SetAgeand the other methods

work.

Declaring methods or data private enables the compiler to find programming mistakes

before they become bugs. Any programmer worth his consulting fees can find a way

around privacy if he wants to. Stroustrup, the inventor of C++, said, “The C++ access

control mechanisms provide protection against accident—not against fraud” (ARM,

1990).

148 Day 6

LISTING6.2 continued

ANALYSIS

The classKeyword

Syntax for the classkeyword is as follows:

class class_name

{