Imports System.Text.RegularExpressions
 
Dim Kompletter_Text as String = txtListe.Text
Dim rx As New Regex("Suchwort:")
Dim m As Match = rx.Match(Kompletter_Text)
 
 If m.Success Then
            MsgBox("Der Index lautet " + m.Index.ToString)
 End if

Dim Beginn as Integer
Dim Textinhalt as String = txtListe.Text
 
Beginn  = Textinhalt .IndexOf("Suchwort")
MsgBox("Der Index lautet " + Beginn .ToString)