Function IsStringInFile(sString As String, sPath As String) As Boolean
  On Error GoTo Fehler
  Dim F As Integer
   F = FreeFile
   Open sPath For Input As #F
      content = Input$(FileLen(sPath), F)
   Close
   If InStr(1, content, sString) <> 0 Then IsStringInFile = True Else _
     IsStringInFile = False
   Exit Function
Fehler:
   If Err.Number = 52 Then MsgBox "Datei '" & sPath & "' nicht gefunden!", _
     vbCritical, "Stop!"
End Function
 
Private Sub Command1_Click()
   MsgBox IsStringInFile("<string nach dem du suchst>", "<pfad zur zu" & _
     "durchsuchenden datei>")
End Sub