as operator in class hearchy : as « Operator « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Operator
3. as

using System; 
 
class A {} 
class B : A {} 
 
class MainClass { 
  public static void Main() { 
    A a = new A(); 
    B b = new B(); 
 
    b = a as B; // cast, if possible 
 
    if(b==null)  
      Console.WriteLine("Cast b = (B) a is NOT allowed."); 
    else 
      Console.WriteLine("Cast b = (B) a is allowed"); 
  } 
}

Cast b = (B) a is NOT allowed.