Csharp/CSharp Tutorial/Class/cast

Conversions of Classes (Reference Types) to an Interface the Object Might Implement

<source lang="csharp">using System; interface Printable {

   string Print();

} class NonPrintablePaper {

   public NonPrintablePaper(int value)
   {
       this.value = value;
   }
   public override string ToString()
   {
       return(value.ToString());
   }
   int value;

} class PrintablePaper: Printable {

   public PrintablePaper(string name)
   {
       this.name = name;
   }
   public override string ToString()
   {
       return(name);
   }
   string Printable.Print()
   {
       return("print...");
   }
   string name;

} class MainClass {

   public static void TryPrinting(params object[] arr)
   {
       foreach (object o in arr)
       {
           Printable printableObject = o as Printable;
           if (printableObject != null)
           Console.WriteLine("{0}", printableObject.Print());
           else
           Console.WriteLine("{0}", o);
       }
   }
   public static void Main()
   {
       NonPrintablePaper s = new NonPrintablePaper(13);
       PrintablePaper c = new PrintablePaper("Tracking Test");
       TryPrinting(s, c);
   }

}</source>

13
print...

Conversions of Classes (Reference Types) To the Base Class of an Object

<source lang="csharp">using System; public class Base {

   public virtual void talk()
   {
       Console.WriteLine("Base");
   }

} public class Derived: Base {

   public override void talk()
   {
       Console.WriteLine("Derived");
   }

} public class Test {

   public static void Main()
   {
       Derived d = new Derived();
       Base b = d;
       
       b.talk();
       Derived d2 = (Derived) b;
       
       object o = d;
       Derived d3 = (Derived) o;
   }

}</source>

Derived