03. oop concepts

Rising Technologies, Jalna (MH). + 91 9423156065, http://www.RisingTechnologies.in 1
Haresh Jaiswal
Rising Technologies, Jalna.

Object Oriented Concepts
 Objects
 Classes
 Data Abstraction
 Encapsulation
 Polymorphism
 Inheritance

Object
 Objects are the basic run-time entities in an OOP
environment.
 They may represent:
 a person,
 a place,
 a bank account or
 any item that the program has to handle.
 Objects are simply variables of type class. Or In pure OOP
terms an object is an instance of a user defined data type
class.

Object
 As the name object-oriented implies, objects are key to
understand object-oriented technology.
 You can look around you & can see many examples of
real-world objects:
 your cell phone,
 your dog,
 your television set,
 your car.

Object
 All these real-world objects share two characteristics:
 they all have state
 and they all have behaviour

Real-World Objects
 A Real World Object : Dog
 have state like
1. Name,
2. Colour,
3. Breed
 have behaviours like
1. Barking,
2. Eating
State Value
Name Tommy
Colour Brown
Breed Labrador

Real-World Objects
 A Real World Object : Car
 have state like
1. Brand,
2. Make,
3. Engine CC
1. Accelerate,
2. Brake,
3. Change Gear State Value
Brand Maruti
Make Swift
Engine CC 1248 CC

Programmatic Objects
 Software/Programmatic objects are modelled after real-
world objects in that they too have state and behaviour.
 A Programmatic object : Box
 have state like
 Height,
 Width,
 Depth
 getDimensions()
 putVolume()

 A Programmatic object : Bank Account
 have state like
 Acct No,
 Acct Holder’s Name,
 Current Balance
 Deposit(),
 Withdrawal()

 A Programmatic object : Employee
 have state like
 Employee ID,
 Employee Name,
 Basic Salary
 getData(),
 putSalary()

 Everything that the software object knows (its state) and
can do (its behaviour) is expressed by the variables and
methods within that object.
 A software/programmatic object maintains:
 its state in variables
 implements its behaviour with methods/functions.

Programming Objects
Object : Student
State (Data)
RollNo
Name
M1, M2, M3
Behaviour (Functions)
getData()
putResult()
Object : Employee
State (Data)
EmpNo
Name
Basic, Ta, Da, Gross
Object : Box
State (Data)
Height
Width
Depth
getDimensions()
putVolume()
getData()
putSalary()
Each object contains Data and Code to manipulate that Data
Or
An object is a bundle of variables and related methods/functions.

Example of Objects
 A software object that modelled your real-world box
would have variables that indicates the box’s current
state:
 Height : 4
 Width : 7
 Depth : 6
 The software object box would also have
methods/functions to:
 getDimensions() : to take dimensions as input from user
 putVolume() : to calculate and print volume of box

Example of Objects
 A software object that modelled your real-world car
would have variables that indicates the car’s current
state:
 speed : 10 mph,
 pedal cadence : 90 rpm,
 current gear is : 5th.
 The software object car would also have
methods/functions to:
 brake,
 change the pedal cadence,
 change gears.

Example of Objects
 You can think of an object as a fancy variable;
 it stores data and you can “make requests” to that object,
asking it to perform operations on itself.

Example of Objects
 You can represent real-world objects using software
objects. You can represent:
 real-world dog as software object in an animation program.
 real-world car as a software object within a game program.

Class
 Classes are actually special kinds of templates from which
you can create objects.
 Definition : Class is a way of binding Data and its
associated Functions/Methods together.
 When you define a class, you define a blueprint for an
abstract data type.

Class
 A class is created to characterise your programmatic
object.
 Everything a programmatic object knows (its state) and
can do (its behaviour) is characterised using variables and
methods defined inside the class.
 A class is a logical abstract but an object has a physical
existence in the memory.

Abstract Data Type
 Defining a Class means creating an abstract data type in
any object oriented programming language.
 A data type can be called abstract, if it do not reveal its
internal implementation to the user of that type.

Abstract Data Type
 There are 2 parts to each ADT:
 The external (public) part, which consists of:
 the conceptual picture (user's view of how the object looks like)
 the conceptual operations (what the user can do to the ADT)
 The internal (private) part, which consists of:
 the representation (how the structure is actually stored)
 the implementation of the operations (the actual code)

Abstraction
 In simple words, abstraction is ‘Hiding implementation
details behind the interface’
 When abstraction is created our concern is limited to
what it can do rather how it is doing it.

Abstraction
 When we drive a car we often need to change the gears
of the vehicle but we are not concerned about the inner
details of the vehicle engine. What matters to us is that
we must shift a gear, that's it. This is abstraction
 Show only those details which matters to the user.

Abstraction
 What exactly is Hiding implementation details behind the
interface?

Abstraction
class box
{
private:
float h, w, d;
public:
void getDimensions()
{
cout << “Enter Height, Width & Depth : “;
cin >> h >> w >> d;
}
void putVolume()
{
cout << “Volume : “ << (h * w * d);
}
};
Class Definition, the internal details/implementation of ADT

Abstraction
Object : Box
State(Data)
Height
Width
Depth
Behaviour/Functions
getDimensions()
putVolume()
An Object of Class Box, user has knowledge about its external
interface only.
Actual implementation,
User has no knowledge
about this part of object.
External Interface to use
this object,
User has knowledge only
about this part of the object.

Encapsulation
 The wrapping of code and data into a single unit is called
as encapsulation.
 Encapsulation binds together data and code to
manipulate that data, it keeps both them safe from
outside interference and mis-use.
 Encapsulation is a protective container that prevents code
and data from being accessed by other code defined
outside the container.
 Creating a Class is the way to implement Encapsulation.

Encapsulation
 Object encapsulates data and operations in one unit
 An object is a bundle of data; who know how to do things
to itself.

Polymorphism
 In object-oriented programming polymorphism means
the ability to appear in many forms.
 polymorphism refers to a programming language's ability
to process objects differently depending on their data
type or class.
 It is the provision of a single interface to entities of
different types.

Polymorphism
 An operation may perform different behaviors in different
instances and the behavior depends upon the type of
data used in the operation.

Polymorphism
 Consider the operation of adding two integer values using
+ operator, then the operation will generate a sum, but if
operands in the operation is of string type then the
operation would produce a third string by concatenation.
5 + 2 => 7 // integer operands
“Rising” + “Tech” => “Rising Tech” // string operands

Polymorphism
 So this process of making an operator to perform
different behaviors in different instances is known as
“operator overloading”

Polymorphism
Class : Shape
---------------------------
Draw()
Object : Circle
---------------------
Draw(circle)
Object : Box
---------------------
Draw(box)
Object : Triangle
---------------------
Draw(triangle)
This figure illustrates that a single function name can be used to handle
different number and different type of arguments.

Polymorphism
 Using a single function name to perform different types of
tasks is known as ‘Function Overloading’
 This is something similar to a particular word having
several different meanings depending on the context.
I Saw a Saw with a Saw Sawing a Saw...

Virtual Functions
 Virtual functions is the ability to redefine methods in
derived classes.
 For example, given a base class shape, polymorphism
enables the programmer to define different area
methods for any number of derived classes, such as
circles, rectangles and triangles.
 No matter what shape an object is, applying
the area method to it will return the correct results.

Polymorphism
Polymorphism
Compile Time
Function
Overloading
Operator
Overloading
Runtime
Virtual
Functions

Polymorphism
 Polymorphism plays an important role in allowing objects
to have different internal structures but to share the
same external interface.

03. oop concepts

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