Imports System
Imports System.IO
Imports System.Text.RegularExpressions
Module Test
Public Sub Main()
Dim sr As New StreamReader("c:\\a.txt")
Dim input As String
Dim pattern As String = "\b(\w+)\s\1\b"
Do While sr.Peek() >= 0
input = sr.ReadLine()
Dim rgx As New Regex(pattern, RegexOptions.IgnoreCase)
Dim matches As MatchCollection = rgx.Matches(input)
If matches.Count > 0 Then
Console.WriteLine("{0} ({1} matches):", input, matches.Count)
For Each match As Match In matches
Console.WriteLine(" " + match.Value)
Next
End If
Loop
sr.Close()
End Sub
End Module