C#: Generic list of enum values

Question

Is there a way to create a method that gets an enum type as a parameter, and returns a generic list of the enum underlying type from it's values, no matter if the underlying type is int\short byte etc'...
I saw this answer of Jon Skeet, but it looks way too complicated.

• Marc Gravell: Example input and output? i.e. do you want the list typed as SomeEnum, or as byte etc?
• gdoron: @MarcGravell as I wrote, I want the generic type to be of the underlying type - byte.

Answer 1

If you want to pass in a Type, it can't really be usefully generic - you'd have to return a single type that isn't directly related to the input, hence something like:

 public static Array GetUnderlyingEnumValues(Type type)
 {
 Array values = Enum.GetValues(type);
 Type underlyingType = Enum.GetUnderlyingType(type);
 Array arr = Array.CreateInstance(underlyingType, values.Length);
 for (int i = 0; i < values.Length; i++)
 {
 arr.SetValue(values.GetValue(i), i);
 }
 return arr;
 }

This is a strongly-typed vector underneath, so you could cast that to int[] etc.

• gdoron: You can set the method to get the Enum type as a generic param, but it won't change a thing, right?
• Marc Gravell: @gdoron indeed, have it <TEnumType> wouldn't help us, because we aren't returning TEnumType[], but rather an int[], byte[], etc - which we can't tell via the generics.

Answer 2

While Marc's answer isn't wrong its somewhat unnecessary. Enum.GetValues(type) returns a TEnum[] so this method is kind of unnecessary as if you know the underlying type you can just cast TEnum[] to its underlying type array.

var underlyingArray = (int[])Enum.GetValues(typeof(StringComparison));

is valid C# that will compile and won't throw an exception at runtime. Since you wanted a list once you have the array you can pass it to the List<Tunderlying> constructor or you can just call the ToArray() extension method.

Edit: you could write the function as such::

public static TUnderlying[] GetValuesAs<TUnderlying>(type enumType)
{
 return Enum.GetValues(enumType) as TUnderlying[];
}

But then you would have to know the underlying type first.

• gdoron: Wow thanks! But still you can't return the strongly type list a function, right?
• Michael B: That's correct Enums are not generic types in the traditional way, if enums were generic like say MyEnum: Enum<int> then this would be possible.