1. Chapter: 09
Inheritance
Lecture: 33
Date: 10.10.2012

2. Class Hierarchies

3. Public and Private Inheritance
class employee //base class
{ };
class teacher : public employee //publicly-derived
{ };
class teacher : private employee //privately-derived
{ };

4. Public and Private Inheritance

5. Levels of Inheritance
 Classes can be derived from classes that are themselves
derived.

6. Levels of Hierarchies

7. Multiple Inheritance
 A class can be derived from more than one base class

8. Multiple Inheritance

9. Aggregation: Classes Within Classes
 Both inheritance and aggregation are class
relationships.
 Inheritance is “kind of” relationship - association.
 Aggregation is “has a” relationship - association
 Def. Aggregation - Several things grouped together
or considered as a whole.

10. Aggregation: Classes Within Classes
 Both inheritance and aggregation are class
relationships.
 Inheritance is “kind of” relationship - association.
 Aggregation is “has a” relationship - association
 Def. Aggregation - Several things grouped together
or considered as a whole.

11. Aggregation: Classes Within Classes
Aggregation may occur when one object is an attribute of another.
In other words, one class contains objects of another class.
Example:
class A
{ };
class B
{
A objA; //object of class A is an attribute of class B
};

12. Aggregation: Classes Within Classes

13. Aggregation: Classes Within Classes

14. Composition: A Stronger Aggregation
 Composition is a stronger form of aggregation, having
all its plus two more
 The part may belong to only one whole
 The lifetime of the part is the same as the lifetime of the whole
 While aggregation is a “has a” relationship, composition
is a “consists of” relationship.

15. Composition: A Stronger Aggregation
 Composition is a stronger form of aggregation, having
all its plus two more
 The part may belong to only one whole
 The lifetime of the part is the same as the lifetime of the whole
 While aggregation is a “has a” relationship, composition
is a “consists of” relationship.