Listing 4.4: A property
class Director
{
    public string FirstName;
    public string LastName;
    public double FullName
     {
        get
         {
            return FirstName + " " + LastName;
         }
     }
}

should read

Listing 4.4: A property
class Director
{
    private string firstName;
    private string lastName;
    public string FullName
     {
        get
         {
            return firstName + " " + lastName;
         }
     }
}