Enum.GetNames() results in unexpected order with negative enum constants

Question

I have the following enum definition (in C#):

public enum ELogLevel
{
    General = -1,  // Should only be used in drop-down box in Merlinia Administrator log settings
    All = 0,       // Should not be used as a level, only as a threshold, effectively same as Trace
    Trace = 1,
    Debug = 2,
    Info = 3,
    Warn = 4,
    Error = 5,
    Fatal = 6,
    Off = 7        // Should not be used as a level, only as a threshold
}

Now, when I do an Enum.GetNames() on this type I get a string array with 9 elements as expected, but the order is All, Trace, ... , Off, General, which is not what I was expecting.

Here's the MSDN documentation for Enum.GetNames():

"Remarks: The elements of the return value array are sorted by the values of the enumerated constants."

What's going on here? I can change my program to take this "functionality" into account, but I'd kind of like to know why .NET is doing what it's doing.

Answer 1

This is a known bug with both GetNames() and GetValues() that was reported here, but ended up getting closed as won't fix:

Yes, this method indeed has a bug where it returns the array of enum values sorted as unsigned-types (-2 is 0xFFFFFFFE and -1 is 0xFFFFFFFF in two's complement, that's why they are showing up at the end of the list) instead of returning values sorted by their signed-types.

Unfortunately, we cannot change the sort order of GetValues because we will break all existing .NET programs that have been written to depend on the current sorting behavior [...]

Looks like you'll have to reorder the values yourself.

Answer 2

Depending on how the sorting occurs, it may be that it is sorting the values as if they were unsigned, in which case, -1 = 0xffffffff, which is of course greater than 7.