Inheritance -OOP

​INT201: Object-Oriented Programming – Inheritance (C#)

By Dr. Prosper Yeng

Learning Objectives (Aligned with Bloom’s Taxonomy).By the end of this lesson, students will be able to:

• Revise on the concepts of object, and class

• Define inheritance in object-oriented programming.

• Explain how inheritance enables code reusability and hierarchical class relationships.

• Demonstrate single and multilevel inheritance in C# through practical code examples (e.g., Car → ElectricCar)

• Differentiate between various types of inheritance

1. What Is an Object?

An object is a real-world entity that has data (attributes) and behavior (methods).

Example: A Car object has:

• brand = Toyota

• color = red

• speed = 120

• Methods: Start(), Stop()

Objects are created from templates or blueprints called classes.

2. What Is a Class?

A class is a blueprint that defines what data and actions its objects can have.

Example:

public class Car {

    public string brand;

    public int speed;

    public void Start() {

        Console.WriteLine("Car started");

    }

    public void Stop() {

        Console.WriteLine("Car stopped");

    }

}

3. Creating an Object instance from a Class

Example:

• Car myCar = new Car();

• myCar.brand = "Toyota";

• myCar.speed = 120;

• myCar.Start();

Output:

Car started

• Inheritance is an object-oriented programming (OOP) principle

• Allows a new class (called the child or derived class)

• To acquire the properties and behaviors of an existing class (called the parent or base class).

• Example: ElectricCar inherits all properties from Car and adds new ones like ChargeBattery().

4. What Is Inheritance?

5. Example: Car → ElectricCar

public class Car {

    public string brand;

    public void Start()

{

Console.WriteLine("Car started");

 }

}

public class ElectricCar : Car {

    public int batteryLevel;

    public void ChargeBattery()

  {

        Console.WriteLine("Battery charging...");

        batteryLevel = 100;

      }

}

6. Using the ElectricCar Class

• ElectricCar myTesla = new ElectricCar();

• myTesla.brand = "Tesla";

• myTesla.Start();        // from Car

• myTesla.ChargeBattery(); // from ElectricCar

• Output:

• Car started

• Battery charging...

7. Calling Parent Method Using base

8.Recap

• Object – real-world entity

• Class – blueprint for objects

• Inheritance – child uses parent’s code

• Inheritance types

• Next class:

• base – calls parent method

• override – modifies parent behavior

• Inheritance type implementation