Question

enum WeekDays
{
    Monday = 0,
    Tuesday = 1,
    Wednesday = 2,
    Thursday = 3,
    Friday = 4,
    Saturday = 5,
    Sunday = 6
}

private void button4_Click(object sender, EventArgs e)
{
    WeekDays days0 = WeekDays.Monday | WeekDays.Tuesday | WeekDays.Wednesday;

    WeekDays days1 = WeekDays.Monday | WeekDays.Tuesday | WeekDays.Wednesday | WeekDays.Thursday;

    WeekDays days2 = WeekDays.Monday | WeekDays.Tuesday | WeekDays.Wednesday | WeekDays.Thursday | WeekDays.Friday;
}

输出是：

days0 = Thursday,
days1 = Thursday,
days2 = 7

有人可以解释这是如何工作的逻辑吗？

Answer 1

基本上，您的枚举不适合按位操作使用。为了适合按位运算，每个不同的值应该由不同的位表示 - 而你只是得到数字0-6。

您获得输出的原因是：

days0为0 | 1 | 2，即3，Thursday
days1为0 | 1 | 2 | 3，仍为3，Thursday
days2是0 | 1 | 2 | 3 | 4，即7，这不是您枚举中的命名值

为了使你的枚举适合于按位运算，你应该这样声明：

[Flags] // Affects string parsing and formatting
enum BitwiseWeekDays
{
    None = 0,
    Monday = 1 << 0,
    Tuesday = 1 << 1,
    Wednesday = 1 << 2,
    Thursday = 1 << 3,
    Friday = 1 << 4,
    Saturday = 1 << 5,
    Sunday = 1 << 6
}

现在每个值都由一个单独的位表示，因此您可以＆＃34;或＆＃34;他们在一起将它们结合起来。

Answer 2

0 | 1 | 2 = (bitwise  00 | 01 | 10 = 11 ) = 3
0 | 1 | 2 | 3 = (bitwise  00 | 01 | 10 | 11 = 11 ) = 3
0 | 1 | 2 | 3 | 4 = (bitwise  000 | 001 | 010 | 011 | 100 = 111 ) = 7

Bit智能操作符如何与Enums一起使用

2 个答案: