Csharp/C Sharp/Language Basics/as

as operator

 

using System;
   
class Employee { }
   
class ContractEmployee : Employee { }
   
class CastExample5
{
    public static void Main ()
    {
        Employee e = new Employee();
        Console.WriteLine("e = {0}", e == null ? "null" : e.ToString());
   
        ContractEmployee c  = e as ContractEmployee;
        Console.WriteLine("c = {0}", c == null ? "null" : c.ToString());
    }
}

Using the as Keyword to Work with an Interface

 

using System;
   
public interface IPrintMessage
{
    void Print();
};
   
class Class1
{
    public void Print()
    {
        Console.WriteLine("Hello from Class1!");
    }
}
   
class Class2 : IPrintMessage
{
    public void Print()
    {
        Console.WriteLine("Hello from Class2!");
    }
}
   
class MainClass
{
    public static void Main()
    {
        PrintClass   PrintObject = new PrintClass();
   
        PrintObject.PrintMessages();
    }
}
   
class PrintClass
{
    public void PrintMessages()
    {
        Class1      Object1 = new Class1();
        Class2      Object2 = new Class2();
   
        PrintMessageFromObject(Object1);
        PrintMessageFromObject(Object2);
    }
   
    private void PrintMessageFromObject(object obj)
    {
        IPrintMessage PrintMessage;
   
        PrintMessage = obj as IPrintMessage;
        if(PrintMessage != null)
            PrintMessage.Print();
    }
}