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Language: VB4/32,VB5,VB6
Expertise: Intermediate
Aug 19, 2000



Building the Right Environment to Support AI, Machine Learning and Deep Learning

ArrayToListbox - Add an array of strings to a ListBox or ComboBox

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal _
    hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, _
    lParam As Any) As Long
Private Declare Function LockWindowUpdate Lib "user32" Alias "LockWindowUpdate" _
    (ByVal hwndLock As Long) As Long

Private Const LB_ADDSTRING = &H180
Private Const LB_RESETCONTENT = &H184
Private Const CB_ADDSTRING = &H143
Private Const CB_RESETCONTENT = &H14B

' Add an array of string to a listbox or combo box
' using API functions, and optionally clearing it first
' This procedure is faster than the one based on AddItem methods,
' especially with ComboBox controls, and reduces flickering
' FIRST and LAST indicate which portion of the array
' should be considered; they default to the first
' and last element, respectively

Sub ArrayToListBox(ctrl As Object, arr As Variant, Optional clearIt As Boolean, _
    Optional ByVal First As Variant, Optional ByVal Last As Variant)
    Dim msgReset As Long
    Dim msgAdd As Long
    Dim hWnd As Long
    Dim index As Long
    If TypeOf ctrl Is ListBox Then
        msgReset = LB_RESETCONTENT
        msgAdd = LB_ADDSTRING
    ElseIf TypeOf ctrl Is ComboBox Then
        msgReset = CB_RESETCONTENT
        msgAdd = CB_ADDSTRING
        ' none of the above, exit
        Exit Sub
    End If
    If IsMissing(First) Then First = LBound(arr)
    If IsMissing(Last) Then Last = UBound(arr)
    ' disable redrawing
    hWnd = ctrl.hWnd
    LockWindowUpdate hWnd
    ' clear control if requested
    If clearIt Then
        SendMessage hWnd, msgReset, 0, 0
    End If
    ' add all items in the array
    For index = First To Last
        SendMessage hWnd, msgAdd, 0, ByVal CStr(arr(index))
    ' re-enable redrawing
    LockWindowUpdate 0
End Sub

Francesco Balena
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