Dim TestString As String = "Whatis4compareToABig44Number"
Dim LstFoundChar As List(Of String) = New List (Of String)
Dim RepeatedChars As String =""
For i As Integer = 0 to TestString.Length
Dim TestChar As String = Strings.Mid(TestString,i,1)
If LstFoundChar.Contains(TestChar) Then
If RepeatedChars.Contains(TestChar) = False Then
RepeatedChars= RepeatedChars & TestChar
End If
Else
LstFoundChar.Add (TestChar)
End If
Next