#include "CircleWithPrivateDataFields.h" // Defined in Listing 9.9 // Construct a default circle object Circle::Circle() { radius = 1; } // Construct a circle object Circle::Circle(double radius) { this->radius = radius; // or (*this).radius = radius; } // Return the area of this circle double Circle::getArea() { return radius * radius * 3.14159; } // Return the radius of this circle double Circle::getRadius() { return radius; } // Set a new radius void Circle::setRadius(double radius) { this->radius = (radius >= 0) ? radius : 0; }