This document discusses abstract classes in C++ programming. It defines an abstract class as a class designed to be used as a base class that cannot be instantiated and must contain at least one pure virtual function. It provides an example of how to declare an abstract class with a pure virtual function and how to derive a class from the abstract class, implementing the pure virtual functions. Abstract classes are important as a base class when functionality is desired for derived classes but cannot be implemented in the abstract class itself.

1. ABSTRACT CLASS
SUBJECT:PROGRAMMING WITH C++
SUBJECT CODE:15BCI303
CLASS:II B.COM IT
ACADEMIC YEAR:2018-2019 ODD
DATE:28/7/2018
HOUR:1
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2. OVERVIEW OF ABSTRACT CLASS?
 What is abstract class?
 How to make abstract class ?
 How to use abstract class ?
 Importance of abstract class ?
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3. WHAT IS ABSTRACT CLASS?
Abstract class :
 An abstract class is a class that is designed to
be specific used as a base class .
 we can’t create objects of abstract classes.
 An abstract class contains at least one pure
base class.
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4. HOW TO MAKE ABSTRACT CLASS?
 An abstract class contains at least one pure virtual
function. Declare a pure virtual function by using a
pure specifier (= 0) in the declaration of a virtual
member function.
The following is an example of an abstractclass:
class abstract
{
public:
virtual void f() = 0; //pure virtual function that
};
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5. HOW TO USE ABSTRACT CLASS ?
//this is simple program of abstract class.
//pure virtual member
#include <iostream>
using namespace std;
class Abstract {
int x, y;
public:
virtual void setData(int x = 0, int y = 0) = 0;
virtual void printData() = 0;
};
class Derived : public Abstract {
int x, y;
public:
void setData(int a= 0, int b= 0)
{
x = a;
y = b;
}
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6. void printData()
{
cout << "Derived::x = " << x << endl
<< "Derived::y = " << y << endl;
}
};
int main()
{
Derived d;
//new data set.
d.setData(10, 20);
cout << “Set New data " << endl;
d.printData();
}
OUTPUT:
Set New data:
Derived::x =10
Derived::y=20
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7. IMPORTANCE OF ABSTRACT CLASS?
 An abstract class as a base class is needed
when there is functionality that is desired for
all objects that have a type deriving from
Abstract Class, but we cannot be
implemented on the Abstract Class itself.
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8. THANK YOU
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