public static void TestShapes() { string str = null; Console.WriteLine("Hello World!"); Ellipse ellipse2 = new Ellipse(5.7, 34.5); //TODO : Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object. //Console.WriteLine(ellipse2.ToString(null)); //Console.WriteLine(ellipse2.ToString(str)); Console.WriteLine(ellipse2.ToString("R")); Console.WriteLine(ellipse2.ToString("G")); Console.WriteLine("\n"); Rectangle rec = new Rectangle(5.7, 34.5); Console.WriteLine(rec.ToString("R")); Console.WriteLine(rec.ToString("G")); Console.WriteLine("\n"); Cuboid cub = new Cuboid(29.6, 29.6, 29.6); Console.WriteLine(cub.ToString("R")); Console.WriteLine(cub.ToString("G")); Console.WriteLine("\n"); Cylinder cyl = new Cylinder(29.6, 29.6, 29.6); Console.WriteLine(cyl.ToString("R")); Console.WriteLine(cyl.ToString("G")); Console.WriteLine("\n"); Sphere sphere = new Sphere(29.6); //Test bad value //Console.WriteLine(sphere.ToString("BADVALUE")); Console.WriteLine(sphere.ToString("R")); Console.WriteLine(sphere.ToString("G")); Console.WriteLine("\n"); }