Question

myRegex.GetGroupNames()

Seems to return the numbered groups as well… how do I get only the named ones?

A solution using the actual Match object would be fine as well.

Answer 1

public string[] GetGroupNames(Regex re)
{
    var groupNames = re.GetGroupNames();
    var groupNumbers = re.GetGroupNumbers();

    Contract.Assert(groupNames.Length == groupNumbers.Length);

    return Enumerable.Range(0, groupNames.Length)
        .Where(i => groupNames[i] != groupNumbers[i].ToString())
        .Select(i => groupNames[i])
        .ToArray();
}

Actually, this will still fail when the group name and number happen to be the same :\ But it will succeed even when the group name is a number, as long as the number is not the same as its index.