static void Main(string[] args)
{
// One way to implement polymorphism is through an abstract class
Console.WriteLine("We created an interface, but never used it in this example");
Shape rect = new Rectangle(5, 5);
Shape tri = new Triangle(5, 5);
Console.WriteLine("Rect Area " + rect.area());
Console.WriteLine("Trit Area " + tri.area());
// Using the overloaded + on 2 Rectangles
Rectangle combRect = new Rectangle(5, 5) + new Rectangle(5, 5);
Console.WriteLine("combRect Area = " + combRect.area());
Console.Write("Hit Enter to Exit");
string exitApp = Console.ReadLine();
}
static void Main(string[] args)
{
Invoice iv = new Invoice(new object[] { "object", "object" });
iv.SaveToPDF();
iv.SaveToWord();
Shape triangle = new Triangle(); // Watch Shape type here!
// triangle.CallMethod(); won't compile
// 1
try
{
Triangle tr = (Triangle)triangle; // use cast to get an access to interface
tr.CallMethod();
}
catch (InvalidCastException e)
{
Console.WriteLine(e.Message);
}
// 2
Triangle tr2 = triangle as Triangle; // Will give null on unsucessful cast
if (tr2 != null)
{
tr2.CallMethod();
}
else
{
Console.WriteLine("No interface here.");
}
// 3
if (triangle is ISimple)
{
((Triangle)triangle).CallMethod();
}
else
{
Console.WriteLine("No interface here.");
}
}
