具有flags属性的枚举

Question

我有一个枚举：

    [Flags, Serializable,]
    public enum WeekDays {
        Sunday = 1,
        Monday = 2,
        Tuesday = 4,
        Wednesday = 8,
        Thursday = 16,
        Friday = 32,
        Saturday = 64,
        WeekendDays = Sunday | Saturday,
        WorkDays = Monday | Tuesday | Wednesday | Thursday | Friday,
        EveryDay = WeekendDays | WorkDays
    }

并且，我在一个包含WeekDays枚举值的类中有属性WeekDays：

public int WeekDays {get; set;}

例如，WorkDays包含62（从星期一到星期五）
如何检查当前WeekDays属性是否包含当前日期？

Answer 1

Enum有方法HasFlag来确定是否在当前实例中设置了一个或多个位字段。

Answer 2

使用逐位运算符&查看值是否是集合的一部分：

var today = WeekDays.Thursday;
var workdays = WeekDays.WorkDays;
if((today & workdays) == today) {
    // today is a workday
}
if((today & WeekDays.Friday) == today) {
    // it's friday
}

Answer 3

使用&:

    [Flags, Serializable,]
    public enum WeekDays
    {
        Sunday = 1,
        Monday = 2,
        Tuesday = 4,
        Wednesday = 8,
        Thursday = 16,
        Friday = 32,
        Saturday = 64,
        WeekendDays = Sunday | Saturday,
        WorkDays = Monday | Tuesday | Wednesday | Thursday | Friday,
        EveryDay = WeekendDays | WorkDays
    }
    public static WeekDays Days { get; set; }
    private static void Main(string[] args)
    {
        WeekDays today = WeekDays.Sunday;
        Days = WeekDays.WorkDays;
        if ((Days & today) == today)
        {
            Console.WriteLine("Today is included in Days");
        }
        Console.ReadKey();
    }

Answer 4

WeekDays weekDayValue = .... ;
var today = Enum.Parse(typeof(WeekDays),DateTime.Now.DayOfWeek.ToString())
bool matches = ( weekDayValue & today ) == today;

Answer 5

do:

int r = (int)(WeekDays.WorkDays & WeekDays.Sunday)
if (r !=0)
  you have it.

Answer 6

您只需要使用逐位布尔逻辑即可完成此操作。如果你说

WeekDays.Tuesday & WeekDays.WorkDays

则布尔逻辑将返回4（因为4&62＝4）。

本质上是&是说对于每个比特位置，如果两者都是1，则返回该数字。因此，您只需要检查它是否大于0。

要想以当前的格式获得《今日》，你需要做一些数学运算。。。

(int)DateTime.Now.DayOfWeek将返回从0（星期日）至6（星期六）。

我们需要绘制这些地图以匹配您的范围。幸运的是，这对数学很容易做到

int today = Math.Pow(2,(int)DateTime.Now.DayOfWeek);
if (today&WeekDays.WorkDays>0)
    isWorkDay = true;
else
    isWorkDay = false;

Answer 7

获取所有枚举名称和值，然后执行"one_answers"计算以测试WeekDays是否包含当前日期