When developing VBA macros for either AutoCAD or MicroStation it is often necessary to display a list of the layers/levels in the active file in either a ListBox control or ComboBox control. Unfortunately the layer/level names are not sorted in alphabetical order and the VBA UserForm controls do not have their own Sort methods. Using a standard bubble sort routine does a nice job of sorting a string array of layer/level names.

Public Sub BubbleSort(ByRef arr() As String, Optional numEls = -1 As Long, Optional 
Descending As Boolean = False)
    Dim Value As String
    Dim index As Long
    Dim firstItem As Long
    Dim indexLimit As Long
    Dim lastSwap As Long

    ' account for optional arguments
    If numEls = -1 Then
        numEls = UBound(arr)
    End If
    firstItem = LBound(arr)
    lastSwap = numEls

    Do
        indexLimit = lastSwap - 1
        lastSwap = 0
        For index = firstItem To indexLimit
            Value = arr(index)
            If (Value > arr(index + 1)) Xor Descending Then
                ' if the items are not in order, swap them
                arr(index) = arr(index + 1)
                arr(index + 1) = Value
                lastSwap = index
            End If
        Next
    Loop While lastSwap

End Sub

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