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Class 12 Unit 5 Object Oriented Programming

Class 12 

Unit 5 

Object Oriented Programming 

Procedural paradigm

u  It is derived from structured programming.

u  It is based on the concept of procedure call.

u  Program code is divided into procedures, block of code.

u  Procedures are known as routine, subroutines, methods or functions.

u  It is also known as top-down language

u  We can call any procedure at any point during a program execution

Advantages of procedural programming

u  It is excellent for general-purpose programming.

u  Easy to code/ source code is portable

u  Code can be reused in different parts of program, without the need to copy it.

u  Needs less memory

Structural programing

u  It is also known as modular programming.

u  It emphasizes on separating a programs data from its functionality.

u  Based on top-down methodology.

u  Focus on dividing the program into sub parts, hence it simplifies problem solving.

u  Eg: Algol, Pascal, Basic, C


u  Code is well organized

u  Improved decision-making power.

u  Easy to code and write program.

Object oriented programming

u  Object-Oriented Programming is a methodology or paradigm to design a program using classes and objects.

u  Object-oriented programming (OOP) is a programming paradigm based upon objects (having both data and methods) that aims to incorporate the advantages of modularity and reusability.

u   Objects, which are usually instances of classes, are used to interact with one another to design applications and computer programs.

Benefits of object–oriented programming

       Modularity. Encapsulation enables objects to be self-contained, making troubleshooting and collaborative development easier.

       Reusability. Code can be reused through inheritance, meaning a team does not have to write the same code multiple times.

       Productivity. Programmers can construct new programs quicker through the use of multiple libraries and reusable code.

       Easily upgradable and scalable. Programmers can implement system functionalities independently.

       Interface descriptions. Descriptions of external systems are simple, due to message passing techniques that are used for objects communication.

       Security. Using encapsulation and abstraction, complex code is hidden, software maintenance is easier and internet protocols are protected.

       Flexibility. Polymorphism enables a single function to adapt to the class it is placed in. Different objects can also pass through the same interface.

Features of Object oriented Programming


u Any entity that has state and behavior is known as an object. For example, a chair, pen, table, keyboard, bike, etc. It can be physical or logical.

u An Object can be defined as an instance of a class. An object contains an address and takes up some space in memory.


Objects can communicate without knowing the details of each other's data or code. The only necessary thing is the type of message accepted and the type of response returned by the objects.

u An Object is an identifiable entity with some characteristics and behaviour. An Object is an instance of a Class.

u When a class is defined, no memory is allocated but when it is instantiated (i.e. an object is created) memory is allocated

u Let us take an Example of a car object.

u A car object named “Maruti” can have data such as color; make, model, speed limit, etc. and functions like accelerate.

u For example: in real life, a car is an object. The car has attributes, such as weight and colour, and methods, such as drive and brake.



u Object: Student

u Data: Roll no., Name:, and Grade

u Function: Study(), Sleep(), Playgame(), Calculate()


u Collection of objects is called class. It is a logical entity.

u   A class is a blueprint for the object.

u Before we create an object, we first need to define the class.

u A class represents a collection of objects having same characteristic properties that exhibit common behavior.

u  for example students, employee, fruits, car.

u Student class has: rollno, name, faculty, address.

u A class is a group of common behavior and functions

u If mobile is a class then Samsung galaxy a32 is a object and its attributes are ram, memory, text, and calling


u Encapsulation is the process of binding both attributes and methods together within a class.

u Binding (or wrapping) code and data together into a single unit are known as encapsulation. For example, a capsule, it is wrapped with different medicines.

u For example: capsule, it is wrapped with different medicines. 

u  Encapsulation is placing the data and the functions that work on that data in the same place. 

u Real time examples, we encapsulate data and methods that operate on it by combining them into a single unit, the class. 

u We can hide private information of a class from the outside world and only disclose functionality that is needed to interact with it this way. 

u We say a class is properly enclosed when it prevents calling code from accessing its private data directly

u Through encapsulation, the internal details of a class can be hidden from outside.

u  It permits the elements of the class to be accessed from outside only through the interface provided by the class.

u Encapsulation means containing all important information inside an object, and only exposing selected information to the outside world.


Realtime Example 1:

u School bag is one of the most real examples of Encapsulation. School bag can keep our books, pens, etc.

Realtime Example 2: 

u When you log into your email accounts such as Gmail, Yahoo Mail there is a lot of internal processes taking place in the backend and you have no control over it.

u When you enter the password for logging, they are retrieved in an encrypted form and verified, and then you are given access to your account.

u You do not have control over it that how the password has been verified. Thus, it keeps our account safe from being misused.


u Abstraction is the concept of object-oriented programming that “shows” only essential attributes and “hides” unnecessary information.

u  The main purpose of abstraction is hiding the unnecessary details from the users.

u  Abstraction is selecting data from a larger pool to show only relevant details of the object to the user.

u It helps in reducing programming complexity and efforts. It is one of the most important concepts of OOPs.

Real life examples of abstraction

u Abstraction shows only important things to the user and hides the internal details,

u for example, when we ride a bike, we only know about how to ride bikes but can not know about how it work? And also we do not know the internal functionality of a bike.

u Another real life example of Abstraction is ATM Machine; All are performing operations on the ATM machine like cash withdrawal, money transfer, retrieve mini-statement…etc. but we can't know internal details about ATM.


u Inheritance in Java is a mechanism in which one object acquires all the properties and behaviors of a parent object.

u The Inheritance has many advantages, the most important of them being the reusability of code

u The reuse of existing classes saves time and effort.

u Inheritance is a process in which one object acquires all the properties and behaviors of its parent object automatically. In such way, you can reuse, extend or modify the attributes and behaviors which are defined in other class. 

u  Using inheritance object of one class can inherit or acquire the properties of the object of another class. Inheritance provides reusability of code. 

u  Inheritance is the process of forming a new class from an existing class

u  It provides code reusability.

Example: For instance, we are humans. We inherit certain properties from the class 'human' such as the ability to speak, breathe, eat, drink, etc. We can also take the example of cars. The class 'car' inherits its properties from the class 'Automobiles' which inherits some of its properties from another class 'Vehicles'.

Single inheritance

u When a class extends another one class only then we  call it a single inheritance.

u The below flow diagram shows that class B extends only one class which is A.

u  Here A is a parent class of B and B would be  a child class of A.

Multi-level inheritance

u In this inheritance, a derived class is created from another derived class.

u In the given example, class c inherits the properties and behavior of class B and class B inherits the properties and behavior of class A.

u So, here A is the parent class of B and class B is the parent class of C. So, here class C implicitly inherits the properties and behavior of class A along with Class B i.e there is a multilevel of inheritance.




Multiple inheritance

u  In this inheritance, a derived class is created from more than one base class. This inheritance is not supported by .NET Languages like C#, F#, etc., and Java Language.

u  In the given example, class c inherits the properties and behavior of class B and class A at the same level. So, here A and Class B both are the parent classes for Class C.

Hierarchical Inheritance

u  In this inheritance, more than one derived class is created from a single base class and further child classes act as parent classes for more than one child class.

u  In the given example, class A has two children class B and class C. Further, class B and class C both are having two children - class D and E; class F and G respectively


Hybrid inheritance

u  This is a combination of more than one inheritance.

u  Hence, it may be a combination of Multilevel and Multiple inheritance or Hierarchical and Multilevel inheritance Hierarchical and Multipath inheritance, or Hierarchical, Multilevel and Multiple inheritances.


Multipath inheritance

u  In this inheritance, a derived class is created from other derived classes and the same base class of other derived classes. This inheritance is not supported by .NET Languages like C#, F#, etc.

u  In the given example, class D inherits the properties and behavior of class C and class B as well as Class A.

u  Both class C and class B inherit the Class A. So, Class A is the parent for Class B and Class C as well as Class D. So, it's making it a Multipath inheritance.



u Polymorphism means "many forms", and it occurs when we have many classes that are related to each other by inheritance.

u In simple words, we can define polymorphism as the ability of a message to be displayed in more than one form. 

u Polymorphism allows us to perform a single action in different ways. In other words, polymorphism allows you to define one interface and have multiple implementations.

u The word “poly” means many and “morphs” means forms, So it means many forms.

Examples of polymorphism

u A real-life example of polymorphism is a person who at the same time can have different characteristics. A man at the same time is a father, a husband, and an employee.

u So the same person exhibits different behavior in different situations. This is called polymorphism. Polymorphism is considered one of the important features of Object-Oriented Programming.

Advantages of Oops

Disadvantages of Oops

We can reuse the code multiple times using class

Bigger program size

Inherit the class to subclass for data redundancy

It required a lot of effort to create

It is easy to maintain and modify

It is slower than other programs

It maintains the security of data

It is not suitable for some sorts of problems

Low-cost development

It takes time to get used to it.

Application of Oops

      Real-Time System design: Real-time system inherits complexities and makes it difficult to build them. OOP techniques make it easier to handle those complexities.

      Hypertext and Hypermedia: Hypertext is similar to regular text as it can be stored, searched, and edited easily. Hypermedia on the other hand is a superset of hypertext. OOP also helps in laying the framework for hypertext and hypermedia.

      AI Expert System: These are computer application that is developed to solve complex problems which are far beyond the human brain. OOP helps to develop such an AI expert System

      Office automation System: These include formal as well as informal electronic systems that primarily concerned with information sharing and communication to and from people inside and outside the organization. OOP also help in making office automation principle.

      Neural networking and parallel programming: It addresses the problem of prediction and approximation of complex-time varying systems. OOP simplifies the entire process by simplifying the approximation and prediction ability of the network.

      Stimulation and modeling system: It is difficult to model complex systems due to varying specifications of variables. Stimulating complex systems require modeling and understanding interaction explicitly. OOP provides an appropriate approach for simplifying these complex models.

      Object-oriented database: The databases try to maintain a direct correspondence between the real world and database object in order to let the object retain it identity and integrity.

      Client-server system: Object-oriented client-server system provides the IT infrastructure creating object-oriented server internet(OCSI) applications.

      CIM/CAD/CAM systems: OOP can also be used in manufacturing and designing applications as it allows people to reduce the efforts involved. For instance, it can be used while designing blueprints and flowcharts. So it makes it possible to produce these flowcharts and blueprint accurately.


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