带有flags属性的枚举

Question

I have the enum:

    [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
    }

And, I have property WeekDays in a class that contain value of WeekDays enum:

public int WeekDays {get; set;}

For example WorkDays contain 62( from Monday to Friday).
How to check that current WeekDays property contain current day?

Answer 1

Enum具有方法HasFlag用于确定是否在当前实例中设置了一个或多个位字段。

Answer 2

Use the bitwise operator & to see if a value is part of a set:

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

Use & :

    [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

You just need to use bitwise boolean logic to do this. if you were to say

WeekDays.Tuesday & WeekDays.WorkDays

then the boolean logic would return 4 (since 4&62 = 4).

Essentially the & is saying that for each bit position if both are 1 then return that number. So you then just need to check if it is > 0.

To get Today in your current format then you'll need to do a bit of maths...

(int)DateTime.Now.DayOfWeek will return the day of the week ranging from 0 (sunday) to 6 (saturday).

We need to map these to match your range. Fortunately this is easy to do with Math.Pow.

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“和”计算以测试WeekDays是否包含当天