Private Sub provfilter()
 
        Dim filterarray(2) As String
        Dim x As Integer
        Dim i As Integer
        Dim y As Integer
        filterarray(0) = worldfilter()
        filterarray(1) = terrainfilter()
        filterarray(2) = klimafilter()
 
        For x = 0 To filterarray.Length - 1 'Anzahl der gesetzten Filter 
        ' ermitteln
            If filterarray(x) <> "" Then
                i = i + 1
                y = x
            End If
        Next
 
        If i = 1 Then 'bei nur einem Filter
            filter = filterarray(y)
 
        ElseIf i > 1 Then 'bei mehr als einem Filter
            filter = "("
 
            For x = 0 To filterarray.Length - 1
 
                If filterarray(x) <> "" Then
                    filter = filter & filterarray(x) & ") AND ("
                End If
 
            Next
             filter = filter.Remove(filter.Length - 6)
 
        ElseIf i = 0 Then
            filter = ""
 
        End If
 
        HauptForm.prov1dv.RowFilter = filter
 
    End Sub