Option Explicit
Sub blablub()
Dim dtVon(1 To 2) As Date
Dim dtBis(1 To 2) As Date
dtVon(1) = "00:30:00": dtVon(2) = "23:30:00"
dtBis(1) = "23:30:00": dtBis(2) = "00:30:00"
Dim tmp As String
Dim i As Long
For i = 1 To 2
tmp = tmp & IIf(tmp <> "", vbNewLine & vbNewLine, "") & _
dtVon(i) & " - " & dtBis(i) & " = " & IrgendEinGerassel(dtVon(i), dtBis(i))
Next
MsgBox tmp
End Sub
Function IrgendEinGerassel(ZeitVon As Date, ZeitBis As Date) As Date
Dim t1 As Date
Dim t2 As Date
t1 = DateAdd("d", 1, Format$(ZeitVon, "dd.mm.yyyy")) & " " & TimeValue(ZeitVon)
t2 = DateAdd("d", 1 + Abs(ZeitVon > ZeitBis), Format$(ZeitBis, "dd.mm.yyyy")) & " " & TimeValue(ZeitBis)
IrgendEinGerassel = t1 - t2
End Function