Lecture 4 inheritance , polymorphism.pptx

Explains on the object oriented programming in c++ inheritance polymorphism and other types of object oriented programming

1. Inheritance

2. Introduction Generalisation & Inheritance What happens when inheritance takes place? Multiple Inheritance Abstract Classes

3. Generalisation(1) Also known as inheritance Car Lorry Vehicle

4. Generalisation(2) Student Lecturer Module * 1 * * teaches attends StudNumb Title ModNumb Person Name

5. Inheritance Example(1) Consider these objects Red Car Yellow Truck Blue Car Green Truck

6. Inheritance Example(2) We can see that there are two car objects and two truck objects Therefore two classes ... Car Truck

7. Common & Different Data But Cars and Trucks have similar attributes (and functions) ... Car Truck TopSpeed Length Weight Colour BootVolume TopSpeed Length Weight Colour FlatBedSpace

8. Data Allocation Car Vehicle Truck float BootVolume float FlatBedSpace float TopSpeed float Length float Weight String Colour

9. Superclasses and subclasses A class defined in terms of another. SuperClass Subclasses

10. An Inheritance Tree Vehicle Car Truck SportsCar Hatchback Articulated Fixed Wheel Base 2 axle 3 axle

11. Data Attribute Location(1) Vehicle Truck Vehicle Truck float length float weight float length float weight float maximumLoad

12. Data Attribute Location(2) Truck Fixed Wheel Base Truck float length float weight float maximumLoad FixedWheelBase float length float weight float maximumLoad

13. Data Attribute Location(3) Fixed Wheel Base 2 axle 3 axle FixedWheelBase float length float weight float maximumLoad 3 axle float length float weight float maximumLoad int axleLoad

14. Inheritance Tree 3 axle Fixed Wheel Base Truck Vehicle A 3 axle truck is a Fixed WheelBase is a truck is a vehicle

15. Inheriting Data and Operations If the data or operation is missing in class try to inherit from higher level class. If the data or operation is present in class then use from this class.

16. Inheriting In Operation Person IncomeTaxCalc Student PayFees Holidays:=20 Lecturer Holidays:=35 SuperTaxCalc Holidays:= 100

17. Multiple Inheritance Vehicle FlyingBoat

18. Abstract Classes(1) Higher up inheritance hierarchy, classes become more general. They can become more abstract. An abstract class has no object instances.

19. Abstract Classes(2) Vehicle WaterVehicle LandVehicle AirVehicle Glider Plane Helicopter Balloon Rocket Abstract Classes

20. Conclusion Generalisation & Inheritance What happens when inheritance takes place? Multiple Inheritance Abstract Classes