[C#] Null 條件運算子(C# 6.0 新功能)

?.：物件為null，指派null給變數；物件為非null，指派屬性值給變數。

?.??：物件為null，指派null給變數；物件為非null、屬性為Null，則指派預設值給變數；物件為非null、屬性為非Null，指派屬性的值給變數。

public class Program
{
   public static void Main(string[] args)
   {
      Student person1 = null;
      string obj1 = person1?.Name ?? "Tim";
      Console.WriteLine(obj1);

      Student person2 = new Student();
      string obj2 = person2?.Name ?? "Tim";
      Console.WriteLine(obj2);
   }
}

public class Student
{
   public string Name { get; set; } = "Mike.Lin";
}