Topic 6612 min readStructured Tutorial

Inheritance in C#: Base and Derived Classes Explained

Quick Answer

Inheritance in C# allows a class (derived) to inherit members from another class (base), promoting code reuse and polymorphism. Base classes define common functionality, while derived classes extend or customize behavior, enabling organized and maintainable code.

Learning Objectives

Explain the purpose of Base and Derived Classes in a practical learning context.
Identify the main ideas, terms, and decisions involved in Base and Derived Classes.
Apply Base and Derived Classes in a simple real-world scenario or practice task.

Introduction to Inheritance in C#

Inheritance is a fundamental concept in object-oriented programming that allows one class to acquire the properties and methods of another.

In C#, inheritance helps create a hierarchy of classes, promoting code reuse and logical organization.

Inheritance enables new classes to receive, or inherit, the properties and methods of existing classes.

Understanding Base and Derived Classes

A base class is the class whose members are inherited by another class. It defines common attributes and behaviors.

A derived class inherits from the base class and can add new members or override existing ones to provide specialized behavior.

Base class is also called the parent or superclass.
Derived class is also called the child or subclass.
Derived classes inherit public and protected members from the base class.
Private members of the base class are not accessible directly in derived classes.

Syntax for Inheritance in C#

In C#, inheritance is declared using a colon (:) followed by the base class name after the derived class name.

Example: public class DerivedClass : BaseClass {}
The derived class inherits all accessible members of the base class.

Access Modifiers and Inheritance

Access modifiers control the visibility of class members to derived classes.

Public members are accessible everywhere, protected members are accessible within derived classes, and private members are hidden.

Use protected to allow derived classes to access members but keep them hidden from other classes.

Example: Base and Derived Classes in C#

Let's look at a simple example demonstrating inheritance with a base class and a derived class.

Code Example

The following code defines a base class 'Animal' and a derived class 'Dog' that inherits from 'Animal'.

Practical Example

The Dog class inherits the Eat method from the Animal base class and adds its own Bark method.

Examples

C# Inheritance Example: Animal and Dog Classes

public class Animal
{
    public void Eat()
    {
        Console.WriteLine("Eating food.");
    }
}

public class Dog : Animal
{
    public void Bark()
    {
        Console.WriteLine("Barking loudly.");
    }
}

// Usage
Dog myDog = new Dog();
myDog.Eat();  // Inherited from Animal
myDog.Bark(); // Defined in Dog

The Dog class inherits the Eat method from the Animal base class and adds its own Bark method.

Best Practices

Use inheritance to represent 'is-a' relationships between classes.
Keep base classes focused on common functionality to maximize reuse.
Avoid deep inheritance hierarchies to reduce complexity.
Use access modifiers carefully to encapsulate class members.
Prefer composition over inheritance when behavior sharing is limited.

Common Mistakes

Using inheritance for code reuse without a true 'is-a' relationship.
Exposing base class private members directly in derived classes.
Creating overly complex inheritance chains.
Ignoring access modifiers leading to unintended member access.
Overriding methods without calling base implementations when needed.

Hands-on Exercise

Create a Base and Derived Class

Define a base class 'Vehicle' with a method 'StartEngine'. Create a derived class 'Car' that inherits from 'Vehicle' and adds a method 'Honk'. Instantiate 'Car' and call both methods.

Expected output: Console output showing 'Engine started.' and 'Car honking.'

Hint: Use the colon syntax for inheritance and ensure methods are public.

Interview Questions

What is the difference between a base class and a derived class in C#?

Interview

A base class provides common members that can be inherited, while a derived class inherits those members and can add or override functionality.

Can a derived class access private members of its base class?

Interview

No, private members of a base class are not accessible directly in derived classes.

How do you declare inheritance in C#?

Interview

Inheritance is declared by placing a colon (:) after the derived class name followed by the base class name.