Table of contents
1.
Introduction
2.
What is Inheritance?
3.
Why & When to Use Inheritance?
4.
How Does Inheritance Make Programming Easy?
4.1.
Without Inheritance
4.2.
Python
4.3.
With Inheritance
4.4.
Python
5.
Types of Inheritance
5.1.
Single Inheritance
5.2.
Multiple Inheritance
5.3.
Multilevel Inheritance
5.4.
Hierarchical Inheritance
5.5.
Hybrid Inheritance
6.
Advantages of Inheritance
6.1.
Code Reusability
6.2.
Code Organization
6.3.
Simplifies Modifications
6.4.
Extensibility
6.5.
Data Hiding
6.6.
Method Overriding
7.
Importance of Inheritance in Programming
7.1.
Foundation for Polymorphism
7.2.
Promotes Code Reusability
7.3.
Enhances Code Maintainability
7.4.
Facilitates Scalability
7.5.
Improves Code Clarity and Organization
7.6.
Encourages the Use of Standardized Coding Practices
8.
Need for Inheritance
8.1.
Avoiding Code Duplication
8.2.
Simplifying Complex Systems
8.3.
Facilitating Code Maintenance
8.4.
Enhancing Feature Expansion
8.5.
Improving Code Readability
8.6.
Enabling Polymorphic Behavior
9.
Implementation of Inheritance
9.1.
Implementation in C++
9.2.
C++
9.3.
Implementation in Java
9.4.
Java
9.5.
Implementation in C#
9.6.
C#
9.7.
Implementation in Python
9.8.
Python
10.
Frequently Asked Questions
10.1.
Can a class inherit from multiple classes?
10.2.
What is method overriding in inheritance?
10.3.
How does inheritance affect access to private members of a class?
10.4.
What are the 4 types of inheritance in OOP?
11.
Conclusion
Last Updated: Aug 31, 2024
Easy

Inheritance in Object-Oriented Programming

Author Ravi Khorwal
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Introduction

Inheritance is a key feature in object-oriented programming that lets one class take on properties and methods from another class. Think of it as a way to create a new class with everything an existing class has, plus something extra or different. This makes programming simpler and cleaner because you don't have to write the same code again for the new class; it already has what it needs from the existing class. 

Inheritance Object Oriented Programming

This article will cover how inheritance works, why it's useful, different types of inheritance, its benefits, and how it's used in programming. We'll also look at examples of how to implement inheritance in various programming languages, making it easier to understand and apply in your codes.

What is Inheritance?

Inheritance in programming is like getting a head start with a toolkit you've been given. Imagine you're building an app and you've got some basic features that many parts of your app will need. Instead of creating these features from scratch every time, you create a general template with all these common features. Now, whenever you work on a new part of your app, you just tell your code, "Start with what's in the template and add what's specific to you." This template is what we call a 'parent class', and the new parts of your app that use this template are 'child classes'. They automatically get everything from the parent class, making your job a lot easier and your code cleaner and more organized.

Why & When to Use Inheritance?

Inheritance is best used when you have a group of classes that share common features but also have their own unique features. It's like having a base model for a product, and then creating variations of this product. You use inheritance because it saves time and reduces errors. Instead of writing the same code over and over for each class, you write the common code once in a parent class and then extend it to other classes. This makes your code easier to manage and update.

For example, in a game, you might have a basic class for all characters with common attributes like health and strength. If you want to create a specific character like a 'Warrior' or 'Mage', you don't have to start from scratch. You can use inheritance to make these new classes inherit the common attributes from the character class and then add unique features like 'magic power' for a Mage. This way, your code is organized, and making changes to the common attributes is easier since you only need to update the parent class.

How Does Inheritance Make Programming Easy?

Inheritance simplifies programming by allowing you to reuse code. Without inheritance, you might find yourself typing out the same code for similar features in different parts of your program. This is not only time-consuming but can also lead to more errors, as each copy of the code needs to be updated individually if changes are needed.

With inheritance, you create a base class with common features and then extend this class to create more specific classes. These new classes inherit all the features of the base class and can also have additional features of their own. This means you write less code, make fewer errors, and save time. It's like building on solid groundwork without starting from zero every time you want to add something new. This approach makes your code more organized and easier to understand, as well.

For Example : 

Suppose you are developing a software system for a school to manage different members, including students and teachers. Both students and teachers share some common attributes like name, age, and ID, but they also have unique features like courses for students and subjects they teach for teachers.

Without Inheritance

  • Python

Python

class Student:

   def __init__(self, name, age, student_id, courses):

       self.name = name

       self.age = age

       self.student_id = student_id

       self.courses = courses

   def display_info(self):

       print(f"Student Name: {self.name}, Age: {self.age}, ID: {self.student_id}, Courses: {self.courses}")

class Teacher:

   def __init__(self, name, age, teacher_id, subjects):

       self.name = name

       self.age = age

       self.teacher_id = teacher_id

       self.subjects = subjects

   def display_info(self):

       print(f"Teacher Name: {self.name}, Age: {self.age}, ID: {self.teacher_id}, Subjects: {self.subjects}")
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With Inheritance

  • Python

Python

class SchoolMember:

   def __init__(self, name, age, id):

       self.name = name

       self.age = age

       self.id = id

   def display_info(self):

       print(f"Name: {self.name}, Age: {self.age}, ID: {self.id}")

class Student(SchoolMember):

   def __init__(self, name, age, student_id, courses):

       super().__init__(name, age, student_id)

       self.courses = courses

   def display_info(self):

       super().display_info()

       print(f"Courses: {self.courses}")

class Teacher(SchoolMember):

   def __init__(self, name, age, teacher_id, subjects):

       super().__init__(name, age, teacher_id)

       self.subjects = subjects

   def display_info(self):

       super().display_info()

       print(f"Subjects: {self.subjects}")
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In the example with inheritance, SchoolMember acts as the base class containing shared attributes and methods. Both Student and Teacher classes inherit from SchoolMember, which reduces code duplication since they no longer need to individually define name, age, and id attributes or the display_info method. They simply add what's unique to them, such as courses for students and subjects for teachers. This not only makes the code cleaner and shorter but also easier to maintain and extend. For instance, if a new attribute or method is needed for all school members, you only need to update the SchoolMember class, and all derived classes will automatically inherit the changes.

Types of Inheritance

 

Types of Inheritance

Single Inheritance

This is the most straightforward kind. You have one parent class and one child class. The child class inherits from the parent class, getting all its features.

Multiple Inheritance

Here, a child class can have more than one parent class. It inherits features from all its parent classes. It's like getting traits from both your mom and your dad.

Multilevel Inheritance

This type involves a chain of inheritance. For example, if class B inherits from class A, and class C inherits from class B, then class C ends up with features from both class A and class B.

Hierarchical Inheritance

In this setup, several child classes inherit from a single parent class. It's as if one parent has many children, each with traits passed down from that parent.

Hybrid Inheritance

This is a combination of two or more of the above types. It's a bit complex because it involves multiple and multilevel inheritance patterns coming together.

Each type of inheritance has its own use cases and is chosen based on what you need in your programming project. For example, single inheritance is simple and great for extending functionality, while multiple inheritance can be powerful but might lead to complexity if not used carefully. 

Advantages of Inheritance

Code Reusability

With inheritance, you can use existing code again without rewriting it. This means less work and fewer chances for errors because you're building on code that already works.

Code Organization

Inheritance helps organize your code better. It groups similar things together, making your program easier to understand and maintain.

Simplifies Modifications

If you need to update or change something, you often only need to do it in one place. Changes in the parent class automatically apply to child classes, saving you time and effort.

Extensibility

You can easily add new features or modify existing ones by creating new classes that inherit from existing ones. This makes your program more flexible and adaptable to future needs.

Data Hiding

Child classes can inherit necessary attributes and methods from parent classes while keeping their own unique features protected. This encapsulation protects the data and prevents unintended interactions.

Method Overriding

Inheritance allows child classes to modify or extend the behaviors of methods inherited from parent classes. This is known as method overriding and enables more specific or appropriate behaviors in child classes.

Importance of Inheritance in Programming

Foundation for Polymorphism

Inheritance is crucial for implementing polymorphism, a main concept in OOP that allows objects of different classes to be treated as objects of a common superclass. This is particularly useful in scenarios like implementing interfaces or method overriding, where you can interact with different objects through a common interface.

Promotes Code Reusability

By allowing new classes to inherit properties and methods from existing classes, inheritance promotes the reuse of code across the program. This not only saves time but also reduces the potential for errors since the inherited code is already tested and verified.

Enhances Code Maintainability

With inheritance, making changes to a common feature across multiple classes becomes much simpler. You only need to update the parent class, and all child classes that inherit from it will automatically receive the updated feature. This centralized management of code enhances maintainability.

Facilitates Scalability

Inheritance makes it easier to scale and extend your software. As new requirements arise, you can create new classes that inherit from existing ones, adding new functionalities while retaining the base features. This scalability is essential for the evolving nature of software projects.

Improves Code Clarity and Organization

Inheritance helps organize code into hierarchical structures, making it clearer and more logical. This hierarchical organization mirrors real-world relationships, making the codebase more intuitive and easier to navigate for developers.

Encourages the Use of Standardized Coding Practices

By fostering a structured approach to code organization, inheritance encourages adherence to standardized coding practices and principles. This standardization is beneficial for collaborative projects, ensuring consistency and improving code quality across the board.

Need for Inheritance

Avoiding Code Duplication

Without inheritance, similar classes would need to have the same code written multiple times. This not only makes the code longer and harder to manage but also increases the chance of errors. Inheritance allows classes to share code, reducing duplication.

Simplifying Complex Systems

In large and complex software systems, managing relationships and functionalities can become overwhelming. Inheritance structures these systems, making them easier to understand and manage by organizing classes into hierarchies.

Facilitating Code Maintenance

Updating a common feature across multiple classes can be tedious and error-prone. With inheritance, changes made to a parent class automatically apply to all child classes, making maintenance easier.

Enhancing Feature Expansion

Inheritance makes adding new features simpler and faster. By inheriting from existing classes, new classes can quickly gain necessary functionalities, allowing developers to focus on implementing new features.

Improving Code Readability

Well-structured code is easier to read and understand. Inheritance helps organize code into clear hierarchies, improving readability and making it easier for new developers to grasp the software's architecture.

Enabling Polymorphic Behavior

Certain programming scenarios require objects of different classes to be treated as if they belong to the same class. Inheritance enables this polymorphism, allowing for more flexible and dynamic code.

Implementation of Inheritance

Implementation in C++

C++ supports single, multiple, and multilevel inheritance. Here's an example of single inheritance:

  • C++

C++

#include <iostream>

using namespace std;

class Vehicle {  // Base class

public:

   void display() {

       cout << "This is a Vehicle" << endl;

   }

};

class Car: public Vehicle {  // Derived class

};

int main() {

   Car myCar;

   myCar.display();

   return 0;

}
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In this example, Car inherits from Vehicle, allowing Car to use the display() method defined in Vehicle.

Implementation in Java

Java supports single and multilevel inheritance but not multiple inheritance with classes. It uses interfaces to achieve a similar effect. Here's an example of single inheritance:

  • Java

Java

class Vehicle {

   public void display() {

       System.out.println("This is a Vehicle");

   }

}

class Car extends Vehicle {

}

public class Main {

   public static void main(String[] args) {

       Car myCar = new Car();

       myCar.display();

   }

}
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Car extends Vehicle, inheriting its display() method.

Implementation in C#

C# is similar to Java in its support for inheritance. Here's how you can implement single inheritance:

  • C#

C#

using System;

public class Vehicle {

   public void Display() {

       Console.WriteLine("This is a Vehicle");

   }

}

public class Car : Vehicle {

}

class Program {

   static void Main(string[] args) {

       Car myCar = new Car();

       myCar.Display();

   }

}

Car inherits from Vehicle, gaining access to the Display() method.

Implementation in Python

Python supports multiple inheritance and is very straightforward with its syntax. Here's an example of single inheritance:

  • Python

Python

class Vehicle:

   def display(self):

       print("This is a Vehicle")




class Car(Vehicle):

   pass


myCar = Car()

myCar.display()
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Output

This is a Vehicle


Car inherits from Vehicle, so it can use the display() method.

Note-: C doesnt support the feature of Inheritence as it doesnt support the important concept of OOPS.

Frequently Asked Questions

Can a class inherit from multiple classes?

Yes, in languages that support multiple inheritance, like Python, a class can inherit from more than one class. However, in languages like Java and C#, multiple inheritance of classes is not supported directly but can be achieved using interfaces.

What is method overriding in inheritance?

Method overriding occurs when a subclass or child class has a method with the same name and signature as a method in the parent class. The method in the child class overrides the method in the parent class, allowing the child class to provide a specific implementation of the method.

How does inheritance affect access to private members of a class?

Private members of a class are not directly accessible by its child classes. However, child classes can access them through public or protected methods defined in the parent class. This is part of encapsulation and data hiding in object-oriented programming.

What are the 4 types of inheritance in OOP?

In object-oriented programming, there are four main types of inheritance: Single Inheritance, where a class inherits from one superclass; Multiple Inheritance, involving inheritance from multiple classes, often implemented using interfaces in Java; Multilevel Inheritance, a chain where a class inherits from a subclass; and Hierarchical Inheritance, where multiple classes inherit from a single superclass.

Conclusion

In this article, we've learned the concept of inheritance in object-oriented programming, which allows a class to inherit properties and methods from another class. We've discussed why and when to use inheritance, how it makes programming easier, the different types of inheritance, and the advantages it brings to code organization, reusability, and maintainability. We also talked about the importance of inheritance in programming and provided examples of how inheritance is implemented in various programming languages like C++, Java, C#, and Python.

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