#include
using namespace std;
const double PI = 3.14159;
class Shape {
public:
virtual double area() const { return 0.0; }
};
class Circle: public Shape {
public:
Circle( int r = 1 ) { radius = r; }
virtual double area() const
{
return PI * radius * radius;
};
protected:
int radius;
};
class Cylinder: public Circle {
public:
Cylinder( int h = 1 ) { height = h; }
virtual double area() const
{
return 2 * PI * radius * height +
2 * Circle::area();
}
private:
int height;
};
void outputShapeArea( const Shape * );
int main()
{
Circle circle;
Cylinder cylinder;
Shape *ptr = 0;
outputShapeArea( &circle );
outputShapeArea( &cylinder );
outputShapeArea( ptr );
return 0;
}
void outputShapeArea( const Shape *shapePtr )
{
const Circle *circlePtr;
const Cylinder *cylinderPtr;
cylinderPtr = dynamic_cast< const Cylinder * >( shapePtr );
if ( cylinderPtr != 0 )
cout << "Cylinder's area: " << cylinderPtr->area();
else {
circlePtr = dynamic_cast< const Circle * >( shapePtr );
if ( circlePtr != 0 )
cout << "Circle's area: " << circlePtr->area();
else
cout << "Neither a Circle nor a Cylinder.";
}
cout << endl;
}