How to enumerate an enum

Question

How can you enumerate an enum in C#?

E.g. the following code does not compile:

public enum Suit
{         


        

Answer 1

enum types are called "enumeration types" not because they are containers that "enumerate" values (which they aren't), but because they are defined by enumerating the possible values for a variable of that type.

(Actually, that's a bit more complicated than that - enum types are considered to have an "underlying" integer type, which means each enum value corresponds to an integer value (this is typically implicit, but can be manually specified). C# was designed in a way so that you could stuff any integer of that type into the enum variable, even if it isn't a "named" value.)

The System.Enum.GetNames method can be used to retrieve an array of strings which are the names of the enum values, as the name suggests.

EDIT: Should have suggested the System.Enum.GetValues method instead. Oops.

Answer 2

foreach (Suit suit in Enum.GetValues(typeof(Suit))) { }

I've heard vague rumours that this is terifically slow. Anyone know? – Orion Edwards Oct 15 '08 at 1:31 7

I think caching the array would speed it up considerably. It looks like you're getting a new array (through reflection) every time. Rather:

Array enums = Enum.GetValues(typeof(Suit));
foreach (Suit suitEnum in enums) 
{
    DoSomething(suitEnum);
}

That's at least a little faster, ja?

Answer 3

Here is a working example of creating select options for a DDL:

var resman = ViewModelResources.TimeFrame.ResourceManager;

ViewBag.TimeFrames = from MapOverlayTimeFrames timeFrame
      in Enum.GetValues(typeof(MapOverlayTimeFrames))
      select new SelectListItem
      {
         Value = timeFrame.ToString(),
         Text = resman.GetString(timeFrame.ToString()) ?? timeFrame.ToString()
      };

Answer 4

Some versions of the .NET framework do not support Enum.GetValues. Here's a good workaround from Ideas 2.0: Enum.GetValues in Compact Framework:

public Enum[] GetValues(Enum enumeration)
{
    FieldInfo[] fields = enumeration.GetType().GetFields(BindingFlags.Static | BindingFlags.Public);
    Enum[] enumerations = new Enum[fields.Length];

    for (var i = 0; i < fields.Length; i++)
        enumerations[i] = (Enum) fields[i].GetValue(enumeration);

    return enumerations;
}

As with any code that involves reflection, you should take steps to ensure it runs only once and results are cached.

Answer 5

public void PrintAllSuits()
{
    foreach(string suit in Enum.GetNames(typeof(Suits)))
    {
        Console.WriteLine(suit);
    }
}

Answer 6

Add method public static IEnumerable<T> GetValues<T>() to your class, like:

public static IEnumerable<T> GetValues<T>()
{
    return Enum.GetValues(typeof(T)).Cast<T>();
}

Call and pass your enum. Now you can iterate through it using foreach:

 public static void EnumerateAllSuitsDemoMethod()
 {
     // Custom method
     var foos = GetValues<Suit>();
     foreach (var foo in foos)
     {
         // Do something
     }
 }