class ParameterClass

{

       public string Name;

       public int IDNumber;

       public ParameterClass()

       {

              //set some default values;

              //since both fields are public they can

              //be overridden if necessary

              this.Name = "";

              this.IDNumber = 0;

       }

}

class OptionalParameters

{

       [STAThread]

       static void Main(string[] args)

       {

              //instantiate a parameter class object

              //and override the name field

              ParameterClass c = new ParameterClass();

              c.Name = "Lamont Adams";

              optionalObject(c);

              //show that the changed ID came back

             Console.WriteLine("c.IDNumber={0}",c.IDNumber);

             //call the method with only defaults

              optionalObject(new ParameterClass());

             //pause so we can see the output

              Console.ReadLine();

      }

       public static void optionalObject(ParameterClass arg)

       {

              //because the parameters received are encapsulated

              //in an object, they are all optional but have

              //a valid state even if not explicitly set by the caller

              Console.WriteLine("arg.Name={0}, arg.IDNumber={1}", arg.Name, arg.IDNumber);

              //change one of the field values

              arg.IDNumber = 10;

       }

}