Imports System
Imports System.Text.RegularExpressions
Public Module Test
Public Sub Main()
Dim rx As New Regex("\b(?\w+)\s+(\k)\b",RegexOptions.Compiled Or RegexOptions.IgnoreCase)
Dim text As String = "this is is a test test."
Dim matches As MatchCollection = rx.Matches(text)
Console.WriteLine("{0} matches found in:", matches.Count)
For Each match As Match In matches
Dim groups As GroupCollection = match.Groups
Console.WriteLine("'{0}' repeated at positions {1} and {2}", _
groups.Item("word").Value, _
groups.Item(0).Index, _
groups.Item(1).Index)
Next
End Sub
End Module