Question

Write a program to demonstrate the use of pure virtual function.

Answer 1

Consider the following example where parent class provides an interface to the base class to implement a function called getArea() as pure virtual function:

#include <iostream.h>

// Base class

class Shape

{

protected:

int width;

int height;

public:

virtual intgetArea() = 0;

void setWidth(int w)

{

width = w;

}

void setHeight(int h)

{

height = h;

}

};

// Derived classes

class Rectangle: public Shape

{

public:

intgetArea()

{

return (width * height); 

}

};

class Triangle: public Shape

{

public:

intgetArea()

{

return (width * height)/2;

}

};

void main(void)

{

Rectangle Rect;

Triangle Tri;

Rect.setWidth(5);

Rect.setHeight(7);

// Print the area of the object.

cout<< "Total Rectangle area: " <<Rect.getArea() <<endl;

Tri.setWidth(5);

Tri.setHeight(7);

// Print the area of the object.

cout<< "Total Triangle area: " <<Tri.getArea() <<endl;

}