Binaryworld - ForceTextBoxNumeric - Force a TextBox control to accept only numeric d ... [ VB.net -> WinForms ]

<System.Runtime.InteropServices.DllImport("user32")> Shared Function _
  GetWindowLong(ByVal hWnd As Integer, ByVal nIndex As Integer) As Integer
End Function

<System.Runtime.InteropServices.DllImport("user32")> Shared Function _
  SetWindowLong(ByVal hWnd As Integer, ByVal nIndex As Integer, _
  ByVal dwNewLong As Integer) As Integer
End Function

' Force a TextBox control to accept only numeric digits
' Cancel the effect by passing Force = False
'
' Note that it only accepts positive integer values

Sub ForceTextBoxNumeric(ByVal ctl As TextBox, Optional ByVal force As Boolean = _
  True)
  Const GWL_STYLE = (-16)
  Const ES_NUMBER = &H2000

  ' get current style
  Dim style As Integer = GetWindowLong(ctl.Handle.ToInt32(), GWL_STYLE)
  If force Then
    style = style Or ES_NUMBER
  Else
    style = style And Not ES_NUMBER
  End If
  ' enforce new style
  SetWindowLong(ctl.Handle.ToInt32(), GWL_STYLE, style)
End Sub