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IE Style Smart TextBox

This code creates a smart input box. Every time you type something into this text box, the first letters of your string are compared against the members of a hidden list box. The code guesses how your string should be completed and finishes it for you, similar to how the latest versions of Microsoft Excel and Internet Explorer behave.

To use this technique, add a list box to your form and set its Visible property to False. This example fills the list at Form_Load with some likely selections. In a real app, you’d add a new element to the list after each user entry is completed. Add this code to the form containing the text and list boxes:

Option Explicit

#If Win32 Then
    Private Const LB_FINDSTRING = &H18F

    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

#Else

        Private Const WM_USER = &H400
        Private Const LB_FINDSTRING = (WM_USER + 16)

        Private Declare Function SendMessage Lib _
                            "User" (ByVal hWnd As Integer, ByVal _
                            wMsg As Integer, ByVal wParam As _
                            Integer, lParam As Any) As Long

#End If

Private Sub Form_Load()
            List1.AddItem "Orange"
            List1.AddItem "Banana"
            List1.AddItem "Apple"
            List1.AddItem "Pear"
End Sub

Private Sub Text1_Change()
            Dim pos As Long
            List1.ListIndex = SendMessage( _
                                            List1.hWnd, LB_FINDSTRING, -1, ByVal _
                                            CStr(Text1.Text))

            If List1.ListIndex = -1 Then
                pos = Text1.SelStart
            Else
                pos = Text1.SelStart
                Text1.Text = List1
                Text1.SelStart = pos
                Text1.SelLength = Len(Text1.Text) - pos
            End If

End Sub

Private Sub Text1_KeyDown(KeyCode As _
                                                Integer, Shift As Integer)

        On Error Resume Next
        If KeyCode = 8 Then 'Backspace
            If Text1.SelLength <> 0 Then
                Text1.Text = Mid$(Text1, 1,  Text1.SelStart - 1)
                KeyCode = 0
            End If
        ElseIf KeyCode = 46 Then 'Del
                If Text1.SelLength <> 0 And _
                        Text1.SelStart <> 0 Then
                        Text1.Text = ""
                        KeyCode = 0
                End If
        End If
End Sub

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