引数が可変(ParamArray)

Function jointText(ParamArray 範囲())
    
    Dim i As Long
    Dim cell As Range
    Const 区切り文字 As String = "-"
    
    For i = 0 To UBound(範囲)
        If 範囲(i).Count > 1 Then
            For Each cell In 範囲(i)
                jointText = jointText & 区切り文字 & cell
            Next cell
        Else
            jointText = jointText & 区切り文字 & 範囲(i)  '2個目以降
        End If
    Next i
    jointText = Right(jointText, Len(jointText) - Len(区切り文字))
    
End Function

※省略可能なOptionalは使えない