C#正则怎么得到表达式的组名？

[z109876543210]

MatchCollection _Matches = Regex.Matches("1111-2222-33333", "(?<a>\\w+)\\-((?<b>\\w+)\\-)?(?<c>\\w+)");

foreach(Match _Match in _Matches)
{
Group _Group = _Match.Groups["b"];
Console.WriteLine(_Group.Value);
}

怎么得到 a、b、c ?

[linuxyf]

string[] a;
a = RegexObj.GetGroupNames();

[linuxyf]

Regex RegexObj = new Regex("(?<a>\\w+)\\-((?<b>\\w+)\\-)?(?<c>\\w+)");