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Spring 2002 CS 403 Class Notes Page 1
Lecture 30 – Tuesday, April 23
• Today:
– Introduction to Object-Oriented Programming
• Reading Assignments For Next Class:
– Chapter 10
• No class Thursday
Spring 2002 CS 403 Class Notes Page 2
Data Abstraction and Object-Oriented
Programming
• Fundamental concepts:
– Classes
– Inheritance
– Polymorphism
• Class design issues:
– Object initialization
– Object finalization
– Copying and equality testing
Spring 2002 CS 403 Class Notes Page 3
Classes
• Basi c structure:
– Private data elements
– Public methods
class foo{
private:
int a;
int b;
public:
foo();
foo(int x);
int c();
};
Spring 2002 CS 403 Class Notes Page 4
Clients
void main(void){
foo f;
f.c();
f.a = 3; //illegal
}
• f is an object with space for 2 ints on main’s
activation record
Spring 2002 CS 403 Class Notes Page 5
Inheritance
class foo2: public fo o{
public:
int d(); //this method c an reference a and b
}
• foo2 inherits the data and method members of foo
• Public members of fooare exported as public members of foo2.
• This makes the foll owing legal:
foo2 f2;
f2.c();
f2.d();
Spring 2002 CS 403 Class Notes Page 6
Polymorphism
• Base class shape:
– Virtual m ethod draw (unimplemented)
– This mak es shape “abstract”
• Not legal to instantia te objects of this class
• Derived classes:
– Triangle
– Rectangle
– Each with its own draw, shade and rotate method
• Client program:
– User cl icks on either “triangle” or “rectangle” and the
appropriate shape is drawn, shaded and rotated
