List Box Cumulative Search

By default, VB list boxes use any keyboard input to find the firstitem beginning with the pressed letter. Where the number of itemsin a list box is large (>100), this is not helpful. Substitutinga binary or hybrid search for the sequential search below speedsup the algorithm substantially for very large lists (>1000items). The code below searches the items in a sorted list boxbased on all the characters typed by the user:

 Global ListBoxSearch$Sub ListBox_KeyPress (KeyAscii As _        Integer)        'Return KeyAscii in case you         'want VB to handle certain charsKeyAscii = SearchListBox_        (Me.ActiveControl, KeyAscii)End SubFunction SearchListBox _        (CurrentActiveControl As Control, _        KeyAscii As Integer)        Dim ListBoxIndex As Integer        Dim Result As Integer                   'Result of string compare        ListBoxSearch$ = ListBoxSearch$ & _                Chr$(KeyAscii)        ListBoxIndex = CurrentActive_                Control.ListIndex While ListBoxIndex < CurrentActive_        Control.ListCount        Result = StrComp(UCase$(List_                BoxSearch$), UCase$(Left$_                (CurrentActiveControl.List_                (ListBoxIndex), Len(ListBox_                Search$))))         If Result <= 0 Then                 CurrentActiveControl.List_                        Index_= ListBoxIndex                 SearchListBox = 0                 Exit Function         End If         ListBoxIndex = ListBoxIndex + 1 Wend ListBoxIndex = CurrentActive_        Control.ListCount - 1 CurrentActiveControl.ListIndex_         = ListBoxIndex SearchListBox = 0End Function

Note: Clearly, the code above is not complete and needs to beaugmented to suit the individual developer. For example, whento clear ListBoxSearch$ is a subject of much consideration (activecontrol changes, user presses arrow keys, and so forth) I implementedthe above scheme on a list of >1500 items with a separate ClearLBSearchsubroutine and a binary/sequential hybrid searching algorithm.

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