HOWTO: Search a ListBox Control Quickly

View products that this article applies to.

This article was previously published under Q161161

SUMMARY

A popular item in a user interface is to "link" a text box to a list box so the nearest match in the list box is selected when the user types text into the text box. This technique can be implemented using pure Visual Basic code, but the Windows API provides a quicker and easier way to do this.

Back to the top

MORE INFORMATION

The technique calls the Windows API SendMessage function using the LB_FINDSTRING message for a list box to locate a partial match for a string in the list box. SendMessage requires the following parameters:

      SendMessage(hWnd, LB_FINDSTRING, wParam, lParam) where

         hWnd    - is the hWnd of the list box.
         wParam  - is a long that specifies the starting point for the
                   search. Use -1 to search the whole list box.
         lParam  - is a long pointer to the string to find.

Back to the top

Step-by-Step Example

Start a new Standard EXE project. Form1 is added by default.
Add a TextBox control (Text1) and a ListBox control (List1) to Form1.

Add the following code to the General Declarations section of Form1:

      Const LB_FINDSTRING = &H18F
      Private Declare Function SendMessage Lib "User32" _
             Alias "SendMessageA" _
         (ByVal hWnd As Long, _
          ByVal wMsg As Integer, _
          ByVal wParam As Integer, _
          lParam As Any) As Long

      Private Sub Form_Load()
         List1.Clear
         List1.AddItem "Apples"
         List1.AddItem "Banana"
         List1.AddItem "Bread"
         List1.AddItem "Break"
         Text1.Text = ""
      End Sub

      Private Sub Text1_Change()
         List1.ListIndex = SendMessage(List1.hWnd, LB_FINDSTRING, -1, _
            ByVal Text1.Text)
      End Sub