// Ch 12 Circle class Demo 1 #include <iostream.h> #include <math.h> const double PI = 3.14159; // class interface (definition) class Circle { public: // constructors Circle(); // default constructor Circle(const Circle &); // copy constructor // member functions (methods) void SetRadius(double); // modifier that sets new radius double Area(); private: // member variables (data) double radius; // circle's radius }; int main() { Circle myCircle; // circle object used as an example double circleArea = 0.0; // area of the circle double userInput = 0.0; // user input for radius of circle cout << "Enter radius of the circle: "; cin >> userInput; myCircle.SetRadius(userInput); circleArea = myCircle.Area(); cout << "The area is " << circleArea << endl << endl; return 0; }// end of main // class implementation // default constructor Circle::Circle() { radius = 0.0; } // copy constructor Circle::Circle(const Circle & Object) { radius = Object.radius; } // sets the radius of the circle void Circle::SetRadius(double IncomingRadius) { radius = IncomingRadius; } // computes the area of the circle double Circle::Area() { return(PI * pow(radius, 2)); }