Question

I came up with this piece of code that converts the set flags in a variable of type Flag Enumeration and returns the set flags as integers.
I’d like to know if this is the best approach.

Example enumeration:

[Flags]
enum Status {
  None = 0x0,
  Active = 0x1,
  Inactive = 0x2,
  Canceled = 0x4,
  Suspended = 0x8
}

The extension method that converts the set flags to array of int that I came up with:

public static class Extensions
{
    public static int[] ToIntArray(this System.Enum o) 
    {
        return o.ToString()
            .Split(new string[] { ", " }, StringSplitOptions.None)
            .Select(i => (int)Enum.Parse(o.GetType(), i))
            .ToArray();
    }
}

This is how I use it:

Status filterStatus = Status.Suspended | Status.Canceled;

int[] filterFlags = filterStatus.toIntArray();

foreach (int flag in filterFlags) {
   Console.WriteLine("{0}\n", flag);
}

It will output:

4
8

As you can see, to get this done I'm doing the following:

1. Converting the variable to string. It outputs something like: Suspended, Canceled
2. Splitting that string into an array of strings: { "Suspended", "Canceled" }
3. Converting that string to the enumeration value with Enum.Parse.
4. Casting the value to an integer.
5. Converting the IEnumerable to int[].

It works, but I just don't think it's the best approach. Any suggestions to improve this bit of code?

Answer 1

To keep it linq-like

var flags = Enum.GetValues(typeof(Status))
                .Cast<int>()
                .Where(f=> f & o == f)
                .ToList();

One gotcha with this approach is that it will include aggregate enumeration values. For example:

[Flags]
public enum Status
{
    None = 0,
    One = 1,
    Two = 2,
    All = One | Two,
}

var flags = Enum.GetValues(typeof(Status))
                .Cast<int>()
                .Where(f=> f & o == f)
                .ToList();

Here flags will have 1, 2, 3, not just 1, 2.