using System; class Animal { public void Eat() { Console.WriteLine("Eating."); } public override string ToString() { return "I am an animal."; } } class Reptile : Animal { } class Mammal : Animal { } class UnSafeCast { static void Main() { Test(new Mammal()); // Keep the console window open in debug mode. Console.WriteLine("Press any key to exit."); Console.ReadKey(); } static void Test(Animal a) { // Cause InvalidCastException at run time // because Mammal is not convertible to Reptile. Reptile r = (Reptile)a; } }