Assume you have a class square. this class has an instance variable, side that is protected and of type double. write the class definition of a subclass of square called fancysquare that has a method called getdiagonal. the getdiagonal method gets no arguments but returns the value of side multiplied by the square root of two.

#include<iostream>

#include<math.h>

using namespace std;

class Square

{

   protected:

   double side;

   public:

   void set(int s)  //sets value of side

   {

       side=s;  

   }

};

class FancySquare : public Square  //inheriting publicly

{

   public:

   double getDiagonal() //returns diagonal of type double

   {

       return side*(sqrt(2));

   }

};

int main() {

   FancySquare f;   //instantiating class

   f.set(4);

   cout<<f.getDiagonal();  //returns diagonal of side 4

return 0;

}

OUTPUT :

5.65685

Explanation:

In the above code, a set() method with public access specifier is defined which takes a value of int type and sets its value to side variable, which is of int type. FancySquare is a class which inherits publicly from class Square and contains a member function getDiagonal() which uses data member side of its parent class Square. In the main method, an object of class FancySquare is created and getDiagonal() is called.