Chapter 04 object oriented programming

CHAPTER - 04
OBJECT ORIENTED PROGRAMMING

Unit I
Programming and Computational
Thinking (PCT-2)
(80 Theory + 70 Practical)
DCSc & Engg, PGDCA,ADCA,MCA.MSc(IT),Mtech(IT),MPhil (Comp. Sci)
Department of Computer Science, Sainik School Amaravathinagar
Cell No: 9431453730
Praveen M Jigajinni
Prepared by
Courtesy CBSE
Class XII

INTRODUCTION
An object-oriented programming (OOP) is a
programming language model which is organized
around "objects" rather than "actions" and data
rather than logic. Before the introduction of the
Object Oriented
Programming paradigm, a program was viewed
as a logical procedure that takes input data,
processes it, and produces output. But in case of
OOP a problem is viewed in terms of objects rather
than procedure for doing it.

BASIC CONCEPTS OF OBJECT ORIENTED
PROGRAMMING

The basic concepts related to OOP are as
follows:
1. Objects
2. Classes
3. Encapsulation
4. Abstraction
5. Data Hiding
6. Polymorphism
7. Inheritance
PROGRAMMING

1. Objects
An object is the basic key concept of
Object Oriented Programming. it can be anything
around us - a person, place, any activity or any other
identifiable entity. Every object is characterised by
i) identity ii) Properties iii) Behaviour
i. Identity : This is the name that identifies an
object.
For example a Student is the name given to anybody
who is pursuing a course
PROGRAMMING

ii. Properties: These are the features or attributes of
the object
For example a student will have his name, age, class,
date of birth etc. as his attributes or properties.
iii. Behaviour: The behaviour of an object signifies
what all functions an object can perform.
For example a student can pass or fail the
examination. A mobile phone can click and store
photographs (behave like a camera).
PROGRAMMING

What is Class?
A class is group of objects with same
attributes and common behaviours. It is
basically a blueprint to create objects. An
object is a basic key concept of OOP but
classes provide an ability to generalize similar
type of objects. Both data and functions
operating on the data are bundled as a unit in
a class for the same category of objects.
PROGRAMMING

for example of the class Mobile_phone
which is represented in the block diagram
below
PROGRAMMING

A class is defined before the creation of objects of
its type. The objects are then created as instances of
this class as shown in the figure.
PROGRAMMING

A class is defined before the creation of objects of
its type. The objects are then created as instances of
this class as shown in the figure.
PROGRAMMING
OBJECTS

A real instance of a class is called an object and
creating the new object is called instantiation.
PROGRAMMING
WHAT IS INSTANTIATION?

OOP FEATURES
Encapsulation
Data Hiding
Data Abstraction
Inheritance
Polymorphism

OOP FEATURES
Encapsulation
Encapsulation is the most basic concept of
OOP. It is the combining of data and the functions
associated with that data in a single unit. In most of
the languages including python, this unit is called a
class. In Fig showing class Mobile_phone, given
under the subtopic Classes, we see that the name of
the class, its properties or attributes and behaviours
are all enclosed under one independent unit. This is
encapsulation, implemented through the unit
named class.

OOP FEATURES
Data Hiding
Data hiding can be defined as the mechanism of
hiding the data of a class from the outside world
or to be precise, from other classes. This is done
to protect the data from any accidental or
intentional access.
In most of the object oriented programming
languages, encapsulation is implemented through
classes. In a class, data may be made private or
public.

OOP FEATURES
Data Hiding
Private data or function of a class cannot be
accessed from outside the class while public data
or functions can be accessed from anywhere. So
data hiding is achieved by making the members of
the class private. Access to private members is
restricted and is only available to the member
functions of the same class.

OOP FEATURES
Data Abstraction
Do you know the inner details of the
monitor of your PC or your mobile phone? What
happens when you switch ON the monitor or
when any call is received by you on your phone?
Does it really matter to you what is happening
inside these devices? No, it does not. Right?
Important thing for you is whether these devices
are working as per your requirement or not?

OOP FEATURES
Data Abstraction
You are never concerned about their inner
circuitry. This is what we call abstraction.
The process of identifying and separating
the essential features without including the
internal details is abstraction.
Only the essential information is
provided to the outside world while the
background details are hidden.

OOP FEATURES
Data Abstraction
Classes use the concept of abstraction. A
class encapsulates the relevant data and functions
that operate on data by hiding the complex
implementation details from the user. The user
needs to focus on what a class does rather than
how it does.

OOP FEATURES
Data Abstraction
Abstraction and Encapsulation are
complementary concepts. Through encapsulation
only we are able to enclose the components of the
object into a single unit and separate the private
and public members. It is through abstraction that
only the essential behaviours of the objects are
made visible to the outside world.
So we can say that encapsulation is the way
to implement data abstraction.

OOP FEATURES
Inheritance
Inheritance is one of the most useful
characteristic of object-oriented programming as
it enforces reusability of code. Inheritance is the
process of forming a new class (derived class)
from an existing class (called the base class). The
data members and the methods associated with
the data are accessible in the inherited class.

OOP FEATURES
Polymorphism
The word Polymorphism is formed from two words
- poly and morph where poly means many and
morph means forms. So polymorphism is the
ability to use an operator or function in various
forms. That is a single function or an operator
behaves differently depending upon the data
provided to them. Polymorphism can be achieved
in two ways:

OOP FEATURES
Polymorphism
Polymorphism can be achieved in two ways:
1. Operator Overloading
2. Function Overloading

OOP FEATURES
Polymorphism
1. Operator Overloading: The '+' operator behaves
differently with different data types. With integers it
adds the two numbers and with strings it
concatenates or joins two strings. For example:
Print 8+9 will give 17 and
Print "Python" + "programming" will give the output
as Pythonprogramming.
This feature where an operator can be used in
different forms is known as Operator Overloading and
is one of the methods to implement polymorphism.

OOP FEATURES
Polymorphism
2. Function Overloading:
Polymorphism in case of functions is a bit
different. A named function can also vary
depending on the parameters it is given. For
example, we define multiple functions with same
name but different argument list as shown below:

OOP FEATURES
Polymorphism
def test(): #function 1
print "hello"
def test(a, b): #function 2
return a+b
def test(a, b, c): #function 3
return a+b+c

Static and Dynamic Binding
Binding is the process of linking the
function call to the function definition. The
body of the function is executed when the
function call is made. Binding can be of two
types:
1. Static Binding.
2. Dynamic Binding.

Static Binding
In this type of binding, the linking of
function call to the function definition is
done during compilation of the program.

Dynamic Binding
In this type of binding, linking of a
function call to the function definition is
done at run time. That means the code of
the function that is to be linked with
function call is unknown until it is executed.
Dynamic binding of functions makes the
programs more flexible.

Advantages of OOP
Object Oriented programming has
following advantages:
1. Simplicity.
2. Modifiability.
3. Extensibility and Maintainability.
4. Re-usability.
5. Security.

Advantages of OOP
The objects in case of OOP are close to
the real world objects, so the complexity of
the program is reduced making the program
structure very clear and simple. For example
by looking at the class Mobile_phone, you
can simply identify with the properties and
behaviour of an actual mobile phone. This
makes the class Mobile_phone very simple
and easy to understand.
1. Simplicity

Advantages of OOP
It is easy to make minor changes in
the data representation or the procedures in
an OO
program. Changes inside a class do not
affect any other part of a program, since the
only public
interface that the external world has to a
class is through the use of methods.
2. Modifiability

Advantages of OOP
It is quite easy to add new features
and extend the program in case of object
oriented programming. It can be simply
done by introducing a few new objects and
modifying some existing ones. The original
base class need not be modified at all. Even
objects can be maintained separately. There
by making locating and fixing problems
easier.
3. Extensibility and Maintainability

Advantages of OOP
For example if a new version of i-
phone is introduced, a new derived class of
the class i_phone for the new version may
be created and no other class in the class
hierarchy need to be modified. Similarly if
any behaviour of a Windows phone
changes, maintenance has to be done only
for the class Windows phone
3. Extensibility and Maintainability

Advantages of OOP
Objects can be reused in different
programs. The class definitions can be
reused in various applications. Inheritance
makes it possible to define subclasses of
data objects that share some or all of the
main class characteristics. It forces a more
thorough data analysis, reduces
development time, and ensures more
accurate coding.
4. Re-usability

Advantages of OOP
Since a class defines only the data it
needs to be concerned with, when an
instance of that class (an object) is run, the
code will not be able to accidentally access
other program data. This characteristic of
data hiding provides greater system security
and avoids unintended data corruption.
5. Security

CLASS TEST
1. Explain in detail the object oriented
programming
2. What is polymorphism? Explain
3. Explain Data Abstraction
4. What is Data Hiding?
5. Explain in detail static and dynamic binding
Class : XII Time: 40 Min
Topic: OOPS Max Marks: 20
Each Question carries 5 marks

Chapter 04 object oriented programming

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