text: #include "Circle.h"
  #include <cmath>
  
  // Circle member function implementation section 
  
  /********************************************
   *             Circle::Circle               *
   * This is the constructor. It initializes  *
   * the radius class member variable.        *
   ********************************************/
  Circle::Circle()
  {	radius = 1.0; 
  }
  
  Circle::Circle(double r)
  {
  	radius = r;
  }
  
  /********************************************
   *             Circle::setRadius            *
   * This function validates the value passed *
   * to it before assigning it to the radius  *
   * member variable.                         *
   ********************************************/
  void Circle::setRadius(double r)
  {	if (r >= 0.0)
  		radius = r; 
  	// else leave it set to its previous value
  }
  
  double Circle::getRadius()
  {
  	return radius;
  }
                  
  /**********************************************
   *               Circle::getArea              *
   * This function calculates and returns the   *
   * Circle object's area. It does not need any *
   * parameters because it can directly access  *
   * the member variable radius.                *
   **********************************************/
  double Circle::getArea()
  {	return 3.14 * pow(radius, 2); 
  }