Page 103 - DCAP404 _Object Oriented Programming

Object-oriented Programming

Notes
Example:
const float g = 9.8;

cout << “The acceleration due to gravity is” << g << “m/s2”;
g=g+4; // ERROR!! Const variables cannot be modified.
The const keyword specifies that the values of the variable will not change throughout the
program. This prevents the programmer from changing the value of variable, like the one in the
example given above. If the keyword, const, has been used while defining the variable, the
compiler will report an error if the programmer tries to modify it.

5.2.1 The Class Keyword

Syntax for the class keyword is as follows.
class class_name
{

// access control keywords here
// class variables and methods declared here
};
You use the class keyword to declare new types. A class is a collection of class member data,
which are variables of various types, including other classes. The class also contains class
functions—or methods—which are functions used to manipulate the data in the class and to
perform other services for the class. You define objects of the new type in much the same way in
which you define any variable. State the type (class) and then the variable name (the object). You
access the class members and functions by using the dot (.) operator. You use access control
keywords to declare sections of the class as public or private. The default for access control is
private. Each keyword changes the access control from that point on to the end of the class or
until the next access control keyword. Class declarations end with a closing brace and a semicolon.

Example:
class Cat
{
public:
unsigned int Age;
unsigned int Weight;
void Meow();

};

Cat Frisky;
Frisky.Age = 8;
Frisky.Weight = 18;
Frisky.Meow();

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