Question

Consider I have this extension method:

public static bool HasAnyFlagInCommon(this System.Enum type, Enum value)
{
    var flags = value.ToString().Split(new string[] { ", " }, 
                                    StringSplitOptions.None);
    foreach (var flag in flags)
    {
        if (type.ToString() == flag)
            return true;
    }
    return false;
}

And the following situation:

[Flags]
enum Bla
{
    A = 0,
    B = 1,
    C = 2,
    D = 4
}

Bla foo = Bla.A | Bla.B;
Bla bar = Bla.A;

bar.HasAnyFlagInCommon(foo); //returns true

I want to check if foo has any flags in common with bar, but there got to be a better way of achiving this behavior in the extension method.

I also tried like this, but is always returns true:

    public static bool HasAnyFlagInCommon(this System.Enum type, Enum value)
    {
        var flags = Enum.GetValues(value.GetType()).Cast<Enum>()
                                 .Where(item => value.HasFlag(item));
        foreach (var flag in flags)
        {
            if (type == flag)
                return true;
        }
        return false;
    }

Answer 1

Something like

public static bool HasAnyFlagInCommon(this System.Enum type, Enum value)
{
    return (((long)type) & ((long)value)) != 0;
}

The & gives 1 for any bit that is set in both enums, so if there are any such bits the result is non-zero.

(I’ve used long in the hope it will work for whatever type underlies the enum; int should be fine in your case.)