Define the class hierarachy as given . Find the area of a circle, rectangle, triangle using virtual function. Creation of Base class object should not be allowed.
Objective
Write a C++ program to demonstrate Pure Virtual Functions and Abstract Classes.
Algorithm / Approach
- Create a
class Shapewith a pure virtual function:virtual void area() = 0;. - Create derived classes (Rectangle, Triangle, Circle) that inherit from
Shape. - Force every derived class to write its own unique implementation of
void area(). - In
main(), create objects of the derived classes and call their area functions.
main.cpp
#include<iostream>
using namespace std;
class Shape {
public:
virtual void area() = 0;
};
class Rectangle : public Shape {
public:
int l,b,ar;
void area() {
cout<<"Enter Length, Breadth ";
cin>>l>>b;
ar = l*b;
cout<<"Area of Rectangle = "<< ar;
cout<< endl;
}
};
class Triangle : public Shape {
public:
int h,b,ar;
void area() {
cout<<"Enter Height, Base ";
cin>>h>>b;
ar = h*b/2;
cout<<"Area of Triangle = "<< ar;
cout<< endl;
}
};
class Circle : public Shape {
public:
int r,ar;
void area() {
cout<<"Enter Radius ";
cin>>r;
ar = 3.14*r*r;
cout<<"Area of Circle = "<< ar;
cout<< endl;
}
};
int main() {
Rectangle r;
r.area();
Triangle t;
t.area();
Circle c;
c.area();
return 0;
}Expected Output
Enter Length, Breadth 4 3 Area of Rectangle = 12 Enter Height, Base 6 8 Area of Triangle = 24 Enter Radius 7 Area of Circle = 153
Explanation of the Program
- A Pure Virtual Function (denoted by
= 0) is a strict contract. It has no code body in the parent class. It simply forces every child class to create its own version of that function. - Any class that contains at least one Pure Virtual Function becomes an "Abstract Class". You are strictly forbidden from creating an object of an Abstract Class (e.g.,
Shape s;will cause a compilation error).
Complexity
Time Complexity
O(1)
Space Complexity
O(1)
