c# - 向枚举类型变量添加多个值

Question

http://msdn.microsoft.com/en-us/library/cc138362.aspx

我引用了上面链接中的代码，它显示了向枚举类型添加值。 但它在我这边不起作用。 代码预期输出: 我得到实际输出:

请引用代码: **
//预期输出: session 日为周二、周四、周五

//实际输出: session 日为周五

//预期输出: session 日为周四、周五

//Actaul 输出: session 日是星期一**

     class Program
{
    enum Days2
    {
        None = 1,
        Sunday = 2,
        Monday = 3,
        Tuesday = 4,
        Wednesday = 5,
        Thursday = 6,
        Friday = 7,
        Saturday = 8
    }



    static void Main(string[] args)
    {
        Days2 meetingDays = Days2.Tuesday | Days2.Thursday;

        // Initialize with two flags using bitwise OR.
        meetingDays = Days2.Tuesday | Days2.Thursday;

        // Set an additional flag using bitwise OR.
        meetingDays = meetingDays | Days2.Friday;


        Console.WriteLine("Meeting days are {0}", meetingDays);
        // Expected Output: Meeting days are Tuesday, Thursday, Friday
        **// Actual Output: Meeting days are  Friday**

        // Remove a flag using bitwise XOR.
        meetingDays = meetingDays ^ Days2.Tuesday;
        Console.WriteLine("Meeting days are {0}", meetingDays);

        // Expected Output: Meeting days are Thursday, Friday
        **// Actaul Output: Meeting days are Monday**

        Console.ReadLine();

    }
}

Answer 1

为了能够使用按位运算来组合枚举值，它们需要具有对应于 2 的幂的值。

此外，您应该使用 Flags 属性标记枚举，并且按照惯例使用零作为“未设置标志”。示例:

[Flags]
public enum Days2 
{
    None = 0,
    Sunday = 1
    Monday = 2,
    Tuesday = 4,
    Wednesday = 8,
    Thursday = 16,
    Friday = 32,
    Saturday = 64
}

参见 C# Programming Guide了解更多信息。