Object Oriented Programming_combined.ppt.pdf

Introduction to
Object Oriented Programming
Gayathri Namasivayam
Introduction to OOP

Topics
●Why use OOP?
●Building blocks of OOP
● Classes
● Objects
●What is OOP?
●OOP concepts
● Abstraction
● Encapsulation
● Inheritance
● Polymorphism
●Advantages vs Disadvantages
●Conclusion
Introduction to OOP

Why use OOP?
●Object Oriented Programming (OOP) is one of the most
widely used programming paradigm
●Why is it extensively used?
● Well suited for building trivial and complex applications
● Allows re-use of code thereby increasing productivity
● New features can be easily built into the existing code
● Reduced production cost and maintenance cost
●Common programming languages used for OOP include
C++, Java, and C#
Introduction to OOP

Building Blocks of OOP: Objects &
Classes
●Object: models a
● Real world object (ex. computer, book, box)
● Concept (ex. meeting, interview)
● Process (ex. sorting a stack of papers or comparing two
computers to measure their performance)
●Class: prototype or blueprint from which objects are
created
Introduction to OOP

Building Blocks of OOP: Objects &
Classes
●Class has
● Set of attributes or properties that describes every object
● Set of behavior or actions that every object can perform
●Object has
● Set of data (value for each of its attribute)
● Set of actions that it can perform
● An identity
●Every object belongs to a class
Introduction to OOP

Real World Example of Objects &
Classes
Object: FordCar1
Behavior
Start, Accelerate,
Reverse, Stop
Attributes
Color: Yellow
Type: Coupe
Model: Mustang
Cylinder: 6
Attributes
Color, Type, Model, Cylinder
Behavior
Start, Accelerate, Reverse, Stop
Class: FordCar
Behavior
Start, Accelerate,
Reverse, Stop
Attributes
Color: Orange
Type: Coupe
Model: Focus
Cylinder: 4
Object: FordCar2
Introduction to OOP

Another Real World Example..
Attributes
Name, Height, Age
Behavior
Speak, Listen, Eat, Run, Walk
Class: Person
Object: Person1
Attributes
Name: Ann
Height: 5’ 4”
Age: 21
Behavior
Speak,
Listen, Eat,
Run, Walk
Attributes
Name: Adam
Height: 5’ 9”
Age: 24
Behavior
Speak,
Listen, Eat,
Run, Walk
Object: Person2
Introduction to OOP

Class
●A class is a set of variables (to represent its attributes) and
functions (to describe its behavior) that act on its variables
Introduction to OOP

Class ShippingBox
int shipping_cost() {
return cost_per_pound*weight;
}
sender_name : string
receiver_name : string
cost_per_pound : int
weight : int
shipping_cost() : int
Introduction to OOP

Object
●Object is an instance of a class that holds data (values) in
its variables. Data can be accessed by its functions
Introduction to OOP

Objects of ShippingBox class
sender_name = Jim
receiver_name = John
cost_per_pound = 5
weight = 10
shipping_cost()
Object BoxB
Object BoxA
sender_name = Julie
receiver_name = Jill
cost_per_pound = 2
weight = 5
shipping_cost()
Class
ShippingBox
Introduction to OOP

What is OOP?
●Paradigm for problem solving by interaction among objects
●It follows a natural way of solving problems
● Ex. Ann wants to start her car
(1) Ann walks to her car
(2) Ann sends a message to the car to start by turning on the ignition
(3)The car starts
Introduction to OOP

Problem Solving in OOP
Problem: Ann wants to start her car
Name = Ann
Age = 21
Speak()
Run()
Walk()
Object Ann
Color = Yellow
Type = Coupe
Model = Mustang
Cylinder = 6
Start()
Accelerate()
Stop()
Object Ann’s car
message
Introduction to OOP

Abstraction
●Extracting essential properties and behavior of an entity
●Class represents such an abstraction and is commonly
referred to as an abstract data type
Ex. In an application that computes the shipping cost of a
box, we extract its properties: cost_per_pound, weight and
its behavior: shipping_cost()
Introduction to OOP

Abstraction
sender_name : string
receiver_name : string
cost_per_pound : int
weight : int
shipping_cost() : int
Class
Shipping Box
Attributes
Sender’s name,
Receiver’s name,
Cost of shipping per pound,
Weight
Behavior
Calculate shipping cost
Abstraction
Introduction to OOP

Encapsulation
sender_name
receiver_name
cost_per_pound
weight
shipping_cost()
●Mechanism by which we combine data and the functions
that manipulate the data into one unit
●Objects & Classes enforce encapsulation
Introduction to OOP

Inheritance
●Create new classes (derived classes) from existing classes
(base classes)
●The derived class inherits the variables and functions of
the base class and adds additional ones!
●Provides the ability to re-use existing code
Introduction to OOP

Inheritance Example
BankAccount CheckingAccount SavingsAccount
customer_name : string
account_type : string
balance : int
insufficient_funds_fee : int
deposit() : int
withdrawal() : int
process_deposit() : int
balance : int
deposit() : int
withdrawal() : int
balance : int
interest_rate : int
deposit() : int
withdrawal() : int
calculate_interest() : int
Introduction to OOP

Inheritance Example
interest_rate : int
calculate_interest() : int
insufficient_funds_fee : int
process_deposit() : int
CheckingAccount SavingsAccount
balance : int
deposit() : int
withdrawal() : int
BankAccount
Introduction to OOP

Topics
●Why use OOP?
●Building blocks of OOP
● Classes
● Objects
●What is OOP?
●OOP concepts
● Abstraction
● Encapsulation
● Inheritance
● Polymorphism*
●Advantages vs Disadvantages
●Conclusion
(* To be covered in the next class)
Introduction to OOP

Disadvantages of OOP
●Initial extra effort needed in accurately modeling the
classes and sub-classes for a problem
●Suited for modeling certain real world problems as
opposed to some others
Introduction to OOP

Conclusion
●Classes & Objects
●Concepts in OOP
● Abstraction
● Encapsulation
● Inheritance
●Advantages & Disadvantages
●Next class
● Be prepared for an in-class activity (based on topics covered
today)!
● Polymorphism in OOP!
Introduction to OOP

Thank you!
Introduction to OOP

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