CODEWITHSUNDEEP
c#datetimedayofweek
kenazs
kenazs

Reputation: 91

How to compare standard DayOfWeek to own with Flag

I have my own DaysOfWeek Flag enum (kind of https://learn.microsoft.com/en-us/previous-versions/ms886541(v=msdn.10))

[Flags]
public enum DayOfWeek
{
    Sunday = 0,
    Monday = 1,
    Tuesday = 2,
    Wednesday = 4,
    Thursday = 8,
    Friday = 16,
    Saturday = 32
}

And I need to compare standard DayOfWeek with mine. How can I do that?

Upvotes: 3

Views: 2242

Answers (4)

idnotbe
idnotbe

Reputation: 1

public enum BitwiseDayOfWeek
{
    Sunday   = 1,
    Monday   = 2,
    Tuesday  = 4,
    Wednesday    = 8,
    Thursday     = 16,
    Friday   = 32,
    Saturday     = 64
}

public class Program
{
    public static void Main(string[] args)
    {
        BitwiseDayOfWeek scheduledDayOfWeek
            = BitwiseDayOfWeek.Saturday | BitwiseDayOfWeek.Sunday;

        // turn System.DayOfWeek (DateTime.Now.DayOfWeek) into BitwiseDayOfWeek
        BitwiseDayOfWeek currentDayOfWeek
            = (BitwiseDayOfWeek)Math.Pow(2, (double)DateTime.Now.DayOfWeek);

        // test if today is the scheduled day
        if ( (currentDayOfWeek & scheduledDayOfWeek) == currentDayOfWeek )
            Console.WriteLine(currentDayOfWeek);

        Console.WriteLine("---------------------");
        Console.ReadLine();
    }
}

Upvotes: 0

kenazs
kenazs

Reputation: 91

Thanks everyone for help. Finally, I have solution

Own DaysOfWeek with flag:

[Flags]
public enum DaysOfWeek
{
    None = 0,
    Sunday = 1 << 0,
    Monday = 1 << 1,
    Tuesday = 1 << 2,
    Wednesday = 1 << 3,
    Thursday = 1 << 4,
    Friday = 1 << 5,
    Saturday = 1 << 6,
}

Since own enum has same order of days, we can write extension method to convert standard DayOfWeek to own

public static class EnumExtensions
{
    public static DaysOfWeek ToFlag(this DayOfWeek dayOfWeek)
    {
        var mask = 1 << (int)dayOfWeek;
        return (DaysOfWeek)Enum.ToObject(typeof(DaysOfWeek), mask);
    }
}

And usage:

  var days = DaysOfWeek.Sunday | DaysOfWeek.Friday;
  var day = DayOfWeek.Sunday;
  var ownDay = day.ToFlag();
  if (days.HasFlag(ownDay))
      // Do whatever;

playground: https://dotnetfiddle.net/sV3yge

Upvotes: 3

Saeid Amini
Saeid Amini

Reputation: 1307

If you change your Enum like this:

[Flags]
public enum DayOfWeek
{
    Sunday = 0,
    Monday = 1,
    Tuesday = 2,
    Wednesday = 3,
    Thursday = 4,
    Friday = 5,
    Saturday = 6
}

You can try this:

class Program
{
    public static bool Equal(DayOfWeek mine, System.DayOfWeek cSharp)
    {
        int mineInt = (int)mine;
        int cSharpInt = (int)cSharp;
        return mineInt == cSharpInt;
    }

    static void Main(string[] args)
    {

        DateTime dateTime = DateTime.Now;
        DayOfWeek dayOfWeek = DayOfWeek.Sunday;

        bool areEqual = Equal(dayOfWeek, dateTime.DayOfWeek);
        Console.WriteLine(areEqual);
        Console.ReadKey();
    }
}

If you can't change your Enum, you can try this:

class Program
{
    public static bool Equal(DayOfWeek mine, System.DayOfWeek cSharp)
    {
        if (mine == DayOfWeek.Friday && cSharp == System.DayOfWeek.Friday       || 
            mine == DayOfWeek.Monday && cSharp == System.DayOfWeek.Monday       || 
            mine == DayOfWeek.Saturday && cSharp == System.DayOfWeek.Saturday   || 
            mine == DayOfWeek.Sunday && cSharp == System.DayOfWeek.Sunday       || 
            mine == DayOfWeek.Thursday && cSharp == System.DayOfWeek.Thursday   ||
            mine == DayOfWeek.Tuesday && cSharp == System.DayOfWeek.Tuesday     || 
            mine == DayOfWeek.Wednesday && cSharp == System.DayOfWeek.Wednesday)
            return true;

        return false;
    }

    static void Main(string[] args)
    {

        DateTime dateTime = DateTime.Now;
        DayOfWeek dayOfWeek = DayOfWeek.Tuesday;

        bool areEqual = Equal(dayOfWeek, dateTime.DayOfWeek);
        Console.WriteLine(areEqual);
        Console.ReadKey();
    }
}

Upvotes: -3

dotNET
dotNET

Reputation: 35380

Since your enum uses the same order of days as the built-in DayOfWeek, all you need to do is to use the variable of DayOfWeek type as the exponent of 2 and then bitwise-AND it with your enum variable.

Something like this (this will check if Monday flag of your enum is 1 or not):

MyDayOfWeek Days = MyDayOfWeek.Monday | MyDayOfWeek.Friday;
DayOfWeek D = DayOfWeek.Monday;
var Mask = 1 << (int)D;

if ((Mask & (int)Days) == Mask)
  //Do whatever;

I have renamed your enum to MyDaysOfWeek, whereas DayOfWeek is the built-in .NET type. You can do the same for any day of week.

Edit

As @HenkHolterman pointed out (thanks for that), you'll have problems with your Sunday set to 0. A Flags enum should normally start with a member named None that is equal to 0 and which indicates that none of the flags of the variable are set.

Upvotes: 3

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