Program 9 BCA Madras University BCA Object Oriented Programming using C++ Practical Madras University Program 9 Create a class to represent a 2-d shape and derive classes to represent a triangle, rectangle and circle. Write a program using run-time polymorphism to compute the area of the figures.

 

BCA

Object Oriented Programming using C++ Practical

Madras University 

Program 9

Create a class to represent a 2-d shape and derive classes to represent a triangle, rectangle and circle. Write a program using run-time polymorphism to compute the area of the figures.

SOURCE CODE:

#include <iostream>

#include <cmath> // for M_PI

using namespace std;

// Base class for 2D shapes

class Shape {

public:

    virtual double area() const = 0; // Pure virtual function to compute area

    virtual ~Shape() = default;      // Virtual destructor

};

// Derived class for Triangle

class Triangle : public Shape {

private:

    double base;

    double height;

public:

    Triangle(double b, double h) : base(b), height(h) {}

    double area() const override {

        cout<<"Triangle Shape"<<endl;

        return 0.5 * base * height;

    }

};

// Derived class for Rectangle

class Rectangle : public Shape {

private:

    double width;

    double height;

public:

    Rectangle(double w, double h) : width(w), height(h) {}

    double area() const override {

                cout<<"Rectangle Shape"<<endl;

        return width * height;

    }

};

// Derived class for Circle

class Circle : public Shape {

private:

    double radius;

public:

    Circle(double r) : radius(r) {}

    double area() const override {

        cout<<"Circle Shape"<<endl;

        return M_PI * radius * radius;

    }

};

int main() {

    // Creating objects for each shape

    Shape* shapes[] = {

        new Triangle(3.0, 4.0),

        new Rectangle(5.0, 6.0),

        new Circle(7.0)

    };

    // Computing and displaying the area of each shape

    for (Shape* shape : shapes) {

        cout << "Area: " << shape->area() << endl;

    }

    // Cleaning up dynamically allocated memory

    for (Shape* shape : shapes) {

        delete shape;

    }

    return 0;

}

OUTPUT:

Triangle Shape

Area: 6

Rectangle Shape

Area: 30

Circle Shape

Area: 153.938

Explanation:

1. Base Class Shape:

   • Shape is an abstract base class with a pure virtual function area().
   • The destructor is virtual to ensure proper cleanup of derived class objects.

2. Derived Classes:

   • Triangle, Rectangle, and Circle classes inherit from Shape.
   • Each class implements the area() function to calculate the area specific to the shape.

3. Main Function:

   • An array of pointers to Shape objects is created, each pointing to a different shape.
   • The area() function is called on each shape object, demonstrating runtime polymorphism.
   • Memory allocated with new is released with delete.