Dim xxx As String = "dfgkldhfgk 8:4 //sfgasgasg"
 
Dim startindex As Integer = xxx.IndexOf(" "c)
If startindex = -1 Then
   MsgBox("Kein Space")
Else
   Dim lastindex As Integer = xxx.IndexOf("//", startindex)
   If lastindex = -1 Then
      MsgBox("Kein // hinter Space gefunden")
   Else
      Dim subxxx As String = xxx.Substring(startindex, lastindex - _
        startindex).Trim
   End If
End If