How to Pass Multiple Enum Values in C#

How do you pass multiple enum values in C#?

When you define the enum, just attribute it with [Flags], set values to powers of two, and it will work this way.

Nothing else changes, other than passing multiple values into a function.

For example:

[Flags]
enum DaysOfWeek
{
   Sunday = 1,
   Monday = 2,
   Tuesday = 4,
   Wednesday = 8,
   Thursday = 16,
   Friday = 32,
   Saturday = 64
}

public void RunOnDays(DaysOfWeek days)
{
   bool isTuesdaySet = (days & DaysOfWeek.Tuesday) == DaysOfWeek.Tuesday;

   if (isTuesdaySet)
      //...
   // Do your work here..
}

public void CallMethodWithTuesdayAndThursday()
{
    this.RunOnDays(DaysOfWeek.Tuesday | DaysOfWeek.Thursday);
}

For more details, see MSDN's documentation on Enumeration Types.

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Edit in response to additions to question.

You won't be able to use that enum as is, unless you wanted to do something like pass it as an array/collection/params array. That would let you pass multiple values. The flags syntax requires the Enum to be specified as flags (or to bastardize the language in a way that's its not designed).

Pass multiple enum to methods and get their values

Here are few steps to follow to get flagged enum :

1. Use 2 exp (n) integer (1, 2, 4, 8, 16, 32, ...)
   to define your enum. Why ? : Actually each active state of your
   enum will take a single bit of a 32 bits integer.
2. Add the Flags attribute.

Then,

    [Flags] 
    public enum Status
    {
        S1 = 1,
        S2 = 2,
        S3 = 4,
        S4 = 8
    }

You can use Enum.HasFlag to check if a specific status is active :

public void DoWork(Status s) 
{
    var statusResult = Enum.GetValues(typeof(Status)).Where(v => s.HasFlag(v)).ToArray() ; 

    // StatusResult should now contains {1, 2}
} 

C# Difference betwen passing multiple enum values with pipe and ampersand

When you do |, you select both. When you do &, you only what overlaps.

Please note that these operators only make sense when you apply the [Flags] attribute to your enum. See http://msdn.microsoft.com/en-us/library/system.flagsattribute.aspx for a complete explanation on this attribute.

As an example, the following enum:

[Flags]
public enum TestEnum
{
    Value1 = 1,
    Value2 = 2,
    Value1And2 = Value1 | Value2
}

And a few test cases:

var testValue = TestEnum.Value1;

Here we test that testValue overlaps with Value1And2 (i.e. is part of):

if ((testValue & TestEnum.Value1And2) != 0)
    Console.WriteLine("testValue is part of Value1And2");

Here we test whether testValue is exactly equal to Value1And2. This is of course not true:

if (testValue == TestEnum.Value1And2)
    Console.WriteLine("testValue is equal to Value1And2"); // Will not display!

Here we test whether the combination of testValue and Value2 is exactly equal to Value1And2:

if ((testValue | TestEnum.Value2) == TestEnum.Value1And2)
    Console.WriteLine("testValue | Value2 is equal to Value1And2");

Assign multiple values to enum elements

Ah I just used a function instead of directly typecasting. Far more easier than to implement something entirely different. I already have lot of code running on this so cant change it much but here is what I did.

public Country GetCountryByTaxID(int taxID)
        {
            if (taxID == 3 || taxID == 4)
            {
                return Country.USA;
            }
            else 
            {
                return Country.Canada;
            }
        }  

how to add multiple enum values with pipe based on conditions?

If SharedAccessBlobPermissions has been declared with [Flags] attribute
you can do some set arithemtics. If initially

  SharedAccessBlobPermissions t = SharedAccessBlobPermissions.Write | SharedAccessBlobPermissions.Read;

Addtion:

  // Add SharedAccessBlobPermissions.Delete and SharedAccessBlobPermissions.Clear 
  t |= SharedAccessBlobPermissions.Delete | SharedAccessBlobPermissions.Clear;

Subtraction:

  // Remove SharedAccessBlobPermissions.Delete
  t = (t | SharedAccessBlobPermissions.Delete) ^ SharedAccessBlobPermissions.Delete;

Combining Enum Values with Bit-Flags

Enum.HasFlag is what you want to use

Console.WriteLine("Custodian is in All: {0}", Role.All.HasFlag(Role.Custodian));

Just noticed that your enum should be defined like this with the Flags attribute and values spaced out by powers of 2

[Flags]
public enum Role
{
    NormalUser = 1,
    Custodian = 2,
    Finance = 4,
    SuperUser = Custodian | Finance,
    All = Custodian | Finance | NormalUser
}

The reason powers of 2 are used for flagged enums is that each power of 2 represents a unique bit being set in the binary representation:

NormalUser = 1 = 00000001
Custodian  = 2 = 00000010
Finance    = 4 = 00000100
Other      = 8 = 00001000

Because each item in the enum has a unique bit set this allows them to be combined by setting their respective bits.

SuperUser  = 6 = 00000110 = Custodian + Finance
All        = 7 = 00000111 = NormalUser + Custodian + Finance
NormOther  = 9 = 00001001 = NormalUser + Other

Notice how each 1 in the binary form lines up with the bit set for the flag in the section above.

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