Public Function RangeExtraction(AList) As String
'AList is a variant that is an array, assumed filled with numbers in ascending order
Const RangeDelim = "-"          'range delimiter
Dim result As String
Dim InRange As Boolean
Dim Posn, i, ub, lb, rangestart, rangelen As Integer
 
result = ""
'find dimensions of AList
ub = UBound(AList)
lb = LBound(AList)
Posn = lb
While Posn < ub
  rangestart = Posn
  rangelen = 0
  InRange = True
  'try to extend the range
  While InRange
    rangelen = rangelen + 1
    If Posn = ub Then
      InRange = False
    Else
      InRange = (AList(Posn + 1) = AList(Posn) + 1)
      Posn = Posn + 1
    End If
  Wend
  If rangelen > 2 Then 'output the range if it has more than 2 elements
    result = result & "," & Format$(AList(rangestart)) & RangeDelim & Format$(AList(rangestart + rangelen - 1))
  Else 'output the separate elements
    For i = rangestart To rangestart + rangelen - 1
      result = result & "," & Format$(AList(i))
    Next
  End If
  Posn = rangestart + rangelen
Wend
RangeExtraction = Mid$(result, 2) 'get rid of first comma!
End Function