Unit III — Overview: Inheritance, Polymorphism & Operator Overloading

Unit III is the largest OOP unit (12 hrs) and contains the highest-impact topics:

1. Inheritance — types, derivation modes (public/private/protected), ambiguity resolution
2. Aggregation vs Classification (composition)
3. Virtual base class
4. Constructor / destructor in derived classes — order of execution
5. Polymorphism — early vs late binding, types
6. Virtual functions — pure virtual, abstract classes
7. Operator overloading — unary, binary, with friend functions
8. Type conversion — basic to user-defined and reverse

Learning outcomes

After Unit III you should be able to:

• Distinguish single, multiple, multilevel, hierarchical, hybrid inheritance
• Choose public/protected/private derivation
• Resolve ambiguities (function overriding, multiple inheritance)
• Use virtual base class to solve the diamond problem
• Order constructor/destructor calls in inheritance chains
• Distinguish early vs late binding
• Implement virtual functions + abstract classes
• Overload unary, binary, and stream operators
• Implement conversion operators

Topic map

Chapter mapping (IPU)

• TB1 (Venugopal): Chapters 13, 14, 15
• TB2 (Balagurusamy): Chapters 7, 8, 9

Typical exam weight

Unit III contributes 3 long questions — highest among all units:

• Explain types of inheritance with diagram and example. — 12.5 marks (very high)
• What are virtual functions? Differentiate early and late binding. — 12.5 marks (very high)
• What is operator overloading? Overload + for a Complex number class. — 12.5 marks (very high)
• What is an abstract class? Why use pure virtual functions? — short or 12.5
• Explain the diamond problem and how virtual base class solves it. — 12.5 marks