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using System;
namespace Obj {
interface Measurable {
double Area ();
};
class Obj : Measurable {
public double Area () {
return 0.0;
}
};
class Rect : Obj {
int x, y, w, h;
public Rect (int vx, int vy, int vw, int vh) {
x = vx;
y = vy;
w = vw;
h = vh;
}
public new double Area () {
return (double)w*h;
}
}
class Circle : Obj {
int x, y, r;
public Circle (int vx, int vy, int vr) {
x = vx;
y = vy;
r = vr;
}
public new double Area () {
return r*r*System.Math.PI;
}
}
class Test {
static public int Main () {
Obj rect, circle;
double sum;
rect = new Rect (0, 0, 10, 20);
circle = new Circle (0, 0, 20);
sum = rect.Area() + circle.Area ();
/* surprise! this calls Obj.Area... */
if (sum != 0.0)
return 1;
/* now call the derived methods */
sum = ((Rect)rect).Area() + ((Circle)circle).Area ();
if (sum != (200 + 400*System.Math.PI))
return 2;
/* let's try to cast to the interface, instead */
sum = ((Measurable)rect).Area() + ((Measurable)circle).Area ();
if (sum != 0.0)
return 3;
return 0;
}
};
};
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