VB.NET tutorial: Make search box workable

Dictionary

Make search box workable

To make the search box workable you need the following code that is applied to the TextChanged event of the text box:

Private Sub Txtbox_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Txtbox.TextChanged
On Error GoTo aa
Dim i As Integer
Dim dr As DataRow
For i = 0 To Lstterms.Items.Count - 1

If Trim(UCase(Txtbox.Text.ToString)) = Trim(UCase(Lstterms.Items(i).ToString)).Substring(0, Txtbox.Text.ToString.Length) Then
'Select matched term
Lstterms.SelectedIndex = i
'Display translation
dr = rs.Tables(0).Rows(i)
Txtresult.Clear()
Txtresult.Text = Trim(dr(1).ToString)
highlight()
Exit Sub
End If
Next
aa: Exit Sub
End Sub

When a user types a word in the search text box TxtBox, This word is used to compare with a word in the list box. If the words are matched the word in the list will be selected and its translation will display in the rich text box Txtresult. The highlight() procedure is called to change colors of the English key terms in the rich text box Txtresult. This procedure will be discussed in the next phase.

If the user chooses to select from the list rather than typing in to the search box, you need another piece of code applied to the SelectedIndexChanged event of the list box:

Private Sub Lstterms_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Lstterms.SelectedIndexChanged
'Display translation when user selects term from the list
On Error GoTo aa
Dim dr As DataRow
dr = rs.Tables(0).Rows(Lstterms.SelectedIndex)
txtresult.Clear() 'clear result
txtresult.Text = Trim(dr(1).ToString)
highlight()


aa: If Err.Description <> "" Then MsgBox(Err.Description)

End Sub

Note: The DataRow dr is used to get data of a selected row of the table.