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OBJECT ORIENTED CONCEPTS

By ARIF

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DEFINITIONOF OOP

The object oriented programming (OOP) is a

programming model where Programs are organized

around object and data rather than action and logic.

OOP allow decomposition of a problem into a number of

entities called Object and then builds data and function

around these objects.

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OOPS CONCEPTS

1. Classes

2. Objects

3. Encapsulation

4. Abstraction5. Inheritance

6. Polymorphism

We will consider an example to understand all

the above OOPs Concepts

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EXAMPLE :

Consider a Banking System in which customers

are allowed to have different types of bank

accounts(such as saving , current and fixed

deposit) in any branch of the bank.

Customers can perform operations such as deposit

money, withdraw money and transfermoney

between accounts with the help of functions

provided by the system such as showbalance,

updatebalance and calculateinterest.

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OOPS CONCEPT 1: CLASSES

A class is a user defined data type with a template that

serves to define its properties.

or

Class is a blueprint of an object that contains variablesfor storing data and functions to performing operations on

these data.

The entire set of data and code of an object can be madea user-defined data type with the help of a class. In fact,

objects are variables of type class.

Class will not occupy any memory space and hence it is

only logical representation of data.

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OOPS CONCEPT 2: OBJECTS

Object is an instance ofa class

An object contains both data and methods that

manipulate that data.

The data represent the state of the object Data can also describe the relationships

between objects.

Example: A Saving Account might have

A balance (the internal state of the account) An owner (some object representing a person)

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CLASSESAND OBJECTS [CONT..]

Class SavingAccount

Account_number

Balance

Owner

Branch

Account_number 101

Balance 1000

Owner abc

Branch b1

Account_number 102

Balance 20,000

Owner xyz

Branch b1

Operations

ShowBalance

updateBalance

CalculateInterest

CLASS

Object

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OOPS CONCEPT 3: ENCAPSULATION

Wrapping up data member and method together into a

single unit (i.e. Class) is called Encapsulation.

Encapsulation provides the ability to hide internaldetails of an object from its users and other object.

The outside user may not be able to change the

state of an object directly. However state of an

object can be altered indirectly in various languagessuch as C# using accessorand mutatormethods

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ENCAPSULATION [CONT..]

Class BankAccount

Private: Account_number

Private: Balance

Private: OwnerPrivate: Branch

Public: ShowBalance

Public: UpdateBalance

Public: calculateInterest

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OOPS CONCEPT 4: ABSTRACTION

Abstraction is the act of representing the essential features without

including the background details.

lets you focus on what the object does instead of how it doesit.

provides you a generalized view of your classes or object byproviding relevant information.

Classes use the concept of abstraction and aredefined as a list of abstract attributes such as size,weight and cost, and functions to operate on these

attributes. They encapsulate all the essentialproperties of the objects that are to be created.Since the classes use the concept of dataabstraction, they are known as Abstract Data Types(ADT).

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ABSTRACTION [CONT..]

Suppose you have 2 account types namely

Saving account(accountno, owner, balance, interest)

Fixed deposit account(accountno, owner, balance, interest,

year)

Abstract information (Necessary and Common

Information) for the object Bank Account" is

balance and account no.So, for Bank Account we will have Abstract Class as

follows:

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ABSTRACTION [CONT..]

BankAccount

Account_number

Balance

Owner

Branch

ShowBalanceAbstract:calculateInterest

Saving Account

Account_number

Balance

OwnerBranch

ShowBalance

Calculate Interest

Fixed Deposit

Account

Account_number

BalanceOwner

Branch

ShowBalance

Calculate Interest

Abstract class

calculateInterest having

different implementation

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OOPS CONCEPT 5: INHERITANCE

Inheritance is the capability of one class to inherit

properties from other class.

It supports the concept of hierarchical classification.

Inheritance is process of object reusability. Enables objects to inherit attributes and behaviors

from other objects, thereby reducing the amount of

new code that must be designed, written, and

tested each time a new program is developed.

Any changes made in the parent class, are

inherently observed in the subclasses.

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INHERITANCE [CONT..]

1. Single Inheritance

2. Multi-Level Inheritance

Class A

Class B

Class A

Class B

Class C

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INHERITANCE [CONT..]

3. Hierarchical Inheritance

4. Multiple Inheritance

Class A

Class B Class C

Class A Class B

Class C

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INHERITANCE [CONT..]

5. Multi-path/Hybrid Inheritance

Class A

Class B Class C

Class D

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INHERITANCE [CONT..]

Current Account

Fixed Deposit Account

Savings Account

Bank Account

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INHERITANCE [CONT..]

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OOPS CONCEPT 6: POLYMORPHISM

Polymorphism means one name many forms.

Essentially, Polymorphism is the capability of oneobject to behaves in multiple ways.

In OOP, it is a language's ability to handle objects

differently based on their runtime type and use. For example:

An operation may exhibit different behavior in differentinstances. The behavior depends upon the types of dataused in the operation. For example, consider the operation of addition. For two

numbers, the operation will generate a sum lf the operands arestrings, then the operation would produce a third string byconcatenation

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POLYMORPHISM [CONT..]

There are two types of polymorphism.

Compile time polymorphism - It is achieved

by overloading functions and operatorsIt is also called Static binding or Early

binding.

Run time polymorphism - It is achievedby overriding virtual functions.

It is also called Dynamic binding.

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POLYMORPHISM [CONT..]

Consider Function calculateInterestto understand

the implementation of polymorphism.

Polymorphism is achieved by overriding functioncalculateInterestin subclasses SavingAccount

and FixedDepositAccount.

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POLYMORPHISM [CONT..]

BankAccount

Account_number

Balance

Owner

Branch

ShowBalance

Calculate Interest

Saving Account

Account_number

BalanceOwner

Branch

ShowBalance

Calculate Interest

Fixed Deposit

Account

Account_numberBalance

Owner

Branch

ShowBalance

Calculate Interest

For saving account

Interest =

P*(N/12)*(R/100)

For Fixed

Deposit account

Interest =P*N*(R/100)

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SUMMARY:

Encapsulation is accomplished by using Class.

Keeps data and methods that accesses that data

into a single unit

Abstraction represents the essential features

without including the background details.

Inheritance helps a class to acquire attributes and

behavior of another class.

Polymorphism allows object to behave in

different forms.