• Download source files - 17.6 Kb
• Download demo project - 9.08 Kb

Introduction

This is a simple code snippet which is used to make an Auto Complete ComboBox.

Using the code

Usage: Call the subroutine from within the ComboBox's KeyPress event handler.

AutoComplete(ByRef cb As ComboBox, _
    ByVal e As System.Windows.Forms.KeyPressEventArgs, _
    Optional ByVal blnLimitToList As Boolean = False)

• cb - ComboBox used to make the Auto Complete ComboBox.
• e - System.Windows.Forms.KeyPressEventArgs used to handle the keyboard inputs.
• blnLimitToList - Optional Boolean value indicating whether the user input is limited to the list values or not.

Code

  ' AutoComplete
  Public Sub AutoComplete(ByRef cb As ComboBox, _
      ByVal e As System.Windows.Forms.KeyPressEventArgs, _
      Optional ByVal blnLimitToList As Boolean = False)

    Dim strFindStr As String

    If e.KeyChar = Chr(8) Then 'Backspace
        If cb.SelectionStart <= 1 Then 
            cb.Text = ""
            Exit Sub
        End If
        If cb.SelectionLength = 0 Then
            strFindStr = cb.Text.Substring(0, 
                             cb.Text.Length - 1)
        Else
            strFindStr = cb.Text.Substring(0, 
                          cb.SelectionStart - 1)
        End If
    Else
        If cb.SelectionLength = 0 Then
            strFindStr = cb.Text & e.KeyChar
        Else
            strFindStr = cb.Text.Substring(0, 
                  cb.SelectionStart) & e.KeyChar
        End If
    End If

    Dim intIdx As Integer = -1

    ' Search the string in the Combo Box List.
    intIdx = cb.FindString(strFindStr)

    If intIdx <> -1 Then ' String found in the List.
        cb.SelectedText = ""
        cb.SelectedIndex = intIdx
        cb.SelectionStart = strFindStr.Length
        cb.SelectionLength = cb.Text.Length
        e.Handled = True
    Else
        If blnLimitToList = True Then
            e.Handled = True
        Else
            e.Handled = False
        End If
    End If
  End Sub

History

• Released on July 30^th, 2005.