How to get ids of not used enums?

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if i have an enum

enum days
{
sun
mon
tue
wed
thu
fri
sat
}

and i have a list of days called D that contains sun,mon,tue,wed

i want to return the enum ids that are not used, so i need the ids of thu,fri and sat

What I have tried:

i was able to get the names itself but i couldn't get the ids


<pre>  
 List<string> Days = Enum.GetNames(typeof(WeekDay)).ToList();
 var closed = Days.Except(D); // D is the list of days i mentioned above

so closed now have thur,fri and sat but i want the ids so what can i replace Enum.getNames with?

Posted 21-Apr-20 20:43pm

Member 14800672

Updated 21-Apr-20 21:37pm

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OriginalGriff · Answer 1 · 2020-04-21T21:36:00

Solution 1

It depends on what D contains: at the moment it contains strings, so you would have to convert the strings back to Enum values:

C#

var closed = Days.Except(D).Select(d => Enum.Parse(typeof(days), d));

Posted 21-Apr-20 21:36pm

OriginalGriff

Bertha Wwallace · Answer 2 · 2020-04-21T21:38:00

Either your list D is already of type days, then

{
    List<days> Days = Enum.GetValues(typeof(days)).OfType<days>().ToList();
    var D = new days[] { days.sun, days.mon, days.tue, days.wed };
    var closed = Days.Except(D);
}

or it consists of strings, then

{
    List<days> Days = Enum.GetValues(typeof(days)).OfType<days>().ToList();
    List<(days, string)> DaysAndNames = Days.Select(day => (day, Enum.GetName(typeof(days), day))).ToList();
    var D = new string[] {"sun", "mon", "tue", "wed" };
    var DAsdays = D.Select(d => DaysAndNames.Where(dn => dn.Item2 == d).Select(dn => dn.Item1).FirstOrDefault()).ToList();
    var closed = Days.Except(DAsdays);
}

Good luck!