Object oriented programming 2

OBJECT
ORIENTED
PROGRAMMING
FPL II Unit II
SPPU-2017/18
Prof. Ansari Aadil
Prof. Ansari Aadil S

Object
 OBJECT is an identifiable entity with some
characteristics and behavior.
 In OOP programming object represents a entity that
can store data and has its interface through functions.
 CLASS is a template/blue-print representing a group of
objects that share common properties and
relationships.

Structure of an
Object Oriented
Program

Features of OOP
• More emphasis on data rather than procedure.
• Programs are divided into object.
• Function and data are tied together in a data
structure.
• Objects communicate with each other through
Functions.
• Data is hidden or cannot be access by external
function.

Principle of OOPS
• Class:
It is type or a category of things.
It is similar to a structure with the difference that it
can also have function.
Ex. Class of Cars. There may be many cars with different
names and brand but all of them will share some
common properties like all of them will have 4
wheels, Speed Limit, Mileage range etc.

OBJECT : It is an instance of class. Ex. Class fruit can have apple as its object.
ABSTRACTION refers to the act of representing essential features without
including the background details or explanations.
ENCAPSULATION :The wrapping up of data and operations / functions (that
operate on the data ) into a single unit (called class) is known as
ENCAPSULATION.
INHERITANCE: Inheritance is the capability of one class of things to inherit
capabilities or properties from other class
POLYMORPHISM: Multiple form of the same thing. It is the ability for a
message or data to be processed in more than one form.

Structure of Object Oriented Program in
c++
#include<iostream.h>
class class-name
{
access-specifiers…
int i,j;
float f;
char ch;
double b;
access-specifiers…
void function-name()
{
statement 1;
statement 2;
}
}
main()
{
class-name.obj-name;
}
Header File
class
Data Variables or fields
Function or Method
Object of class
Class members

Define a Class Type
class class_name
{
permission_label:
member;
permission_label:
member;
...
};
class Rectangle
{
private:
int width;
int length;
public:
void set(int w, int
l);
int area();
};
Body
Header

class Rectangle
{
private:
int width;
int length;
public:
void set(int w, int
l);
int area();
};
Classes & Objects
Rectangle
r1;
Rectangle
r2;
Rectangle
r3;
……
int a;
Objects: Instance of a class

• Information hiding
• To prevent the internal representation from direct access
from outside the class
• Access Specifiers
• public
• may be accessible from anywhere within a program
• private
• may be accessed only by the member functions, and friends of
this class
• protected
• acts as public for derived classes
• behaves as private for the rest of the program
Class Definition - Access Control

Read and print details of a student using class
program in C++
/*C++ program to create class for a student.*/
#include <iostream>
using namespace std;
class student
{
private:
char name[30];
int rollNo;
int total;
float perc;
public:
//member function to get
student's details
void getDetails(void);
//member function to print
student's details
void putDetails(void);
};
//member function definition, outside of the class
void student::getDetails(void){
cout << "Enter name: " ;
cin >> name;
cout << "Enter roll number: ";
cin >> rollNo;
cout << "Enter total marks outof 500: ";
cin >> total;
perc=(float)total/500*100;
}
//member function definition, outside of the class
void student::putDetails(void){
cout << "Student details:n";
cout << "Name:"<< name << ",Roll
Number:" << rollNo << ",Total:" << total <<
",Percentage:" << perc;
}
int main()
{
student std; //object
creation
std.getDetails();
std.putDetails();
return 0;
}
Output: Enter name: mike
Enter roll number: 112
Enter total marks outof 500: 456
Student details:
Name:mike,Roll
Number:112,Total:456,Percentage:91.2

// Program to illustrate the working of objects and
class in C++ Programming
#include <iostream.h>
#include<conio.h>
class Test
{
private:
int data1;
float data2;
public:
void insertIntegerData(int d)
{
data1 = d;
cout << "Number: " << data1;
}
float insertFloatData()
{
cout << "nEnter data: ";
cin >> data2;
return data2;
}
};
int main()
{
Test o1, o2;
float secondDataOfObject2;
o1.insertIntegerData(12);
secondDataOfObject2 = o2.insertFloatData();
cout << "You entered " << secondDataOfObject2;
getch();
}
Output
Number: 12
Enter data: 23.3
You entered 23.3

Data Structure
Data : It is piece of Information
ex . String or any record
Types of Data:
1. Atomic– Single , Non decomposable
ex. 1234
2. Composite or structured – can be broken into sub fields
ex PRN has college code, branch code, student id.

A data structure is a particular way of organizing data in a
computer so that it can be used effectively.
Data structure is linear or non Linear in nature
1.Linear- every item is attach to previous and next item
ex. Array , Linked list, Stack ,Queue
2. Non linear – every item is attached to many other items.
Multidimensional array, Tree , Graph.

Stack
Queue
Linked List Graph Tree

Defining member function
1. Internally defined function- when member function of a
class are defined inside the class itself
#include<conio.h>
class circle
{
float r,a;
public:
void read()
{
cout<<“Enter radius:”;
cin>>r;
}
void compute()
{
a= 3.14 *r * r;
}
void display()
{
cout<<“Area”=<<a; }
};
void main()
{
clrscr();
circle c;
c.read();
c.compute();
c.display();
getch();
}
Output: Enter radius: 5
Area= 78.5

2. Externally defined function
When the member function of a class are defined outside the class.
:: () scope resolution operator is used.
#include<conio.h>
class circle
{
float r,a;
public:
void read();
void compute();
void display();
};
void circle :: read()
{
cin>>r;
}
void circle :: compute()
{
a= 3.14 *r * r;
}
void circle :: display()
{
};
void main()
{
clrscr();
circle c;
c.read();
c.compute();
c.display();
getch();
}
Area= 78.5

3. Inline Member function
If a function is defined outside the class but still to be treated as internally
defined function then such function has to be made “inline” function
#include<conio.h>
class circle
{
float r,a;
public:
void read();
void compute();
void display();
};
inline void circle :: read()
{
cin>>r;
}
inline void circle :: compute()
{
a= 3.14 *r * r;
}
inline void circle :: display()
{
};
void main()
{
clrscr();
circle c;
c.read();
c.compute();
c.display();
getch();
}
Area= 78.5

Constructor
A constructor is a member function of a class which initializes
objects of a class.
• Constructor has same name as the class itself
• Constructors don’t have return type
• A constructor is automatically called when an object is created.
• If we do not specify a constructor, C++ compiler generates a
default constructor for us (expects no parameters and has an
empty body).

Types of Constructors
1. Default Constructors
2. Parameterized Constructors:
3. Copy Constructor

Default Constructors:
Default constructor is the constructor which doesn’t take any
argument. It has no parameters.
#include <iostream.h>
#include<conio.h>
using namespace std;
class construct
{
public:
int a, b;
// Default Constructor
construct()
{
a = 10;
b = 20;
}
};
void main()
{
// Default constructor called automatically
// when the object is created
construct c;
cout << "a: "<< c.a << endl << "b: "<< c.b;
getch();
}
Output:
a: 10
b: 20

Parameterized Constructors
To create a parameterized constructor, simply add parameters to it the way you would to any other
function. When you define the constructor’s body, use the parameters to initialize the object.
#include<conio.h>
class Point
{
private:
int x, y;
public:
// Parameterized Constructor
Point(int x1, int y1)
{
x = x1;
y = y1;
}
int getX()
{
return x;
}
int getY()
{
return y;
}
};
int main()
{
// Constructor called
Point p1(10, 15);
// Access values assigned by constructor
cout << "p1.x = " << p1.getX() << ", p1.y
= " << p1.getY();
return 0;
}
Output:
p1.x = 10, p1.y = 15

Copy Constructor
A copy constructor is a member function which initializes
an object using another object of the same class.
ClassName (const ClassName &old_obj);

Destructors
Destructor is a member function which destructs or deletes an object.
Destructors have same name as the class preceded by a tilde (~)
class test
{
int *p;
public:
test()
{
p=new int;
}
void read()
{
cout<< “ Enter a number: ”;
cin>> *p;
}
void display()
{
cout<< “ Value= “<<*p<< endl;
}
~ test()
{
delete p;
cout<<“Destroyed”;
}
};
void main()
{
clrscr();
test t;
t.read();
t.display();
getch();
}
Output: Enter a number: 5
Value=5;
Destroyed

Object oriented programming 2

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