让TextBox只允许输入数字

Visual Basic Code

Private Declare Function GetWindowLong Lib "user32.dll" Alias "GetWindowLongA"   ( ByVal hwnd As Long, ByVal nIndex As Long )   As Long Private Declare Function SetWindowLong Lib "user32.dll" Alias "SetWindowLongA"   ( ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long )   As Long Private Const GWL_STYLE As Long   =   -16 Private Const ES_NUMBER As Long   =   &H2000 Private Sub Form_Load (   )           Dim lOldStytle As Long         Dim ret As Long         lOldStytle   =   GetWindowLong ( Text1.hwnd, GWL_STYLE )           lOldStytle   =   lOldStytle Or ES_NUMBER         ret   =   SetWindowLong ( Text1.hwnd, GWL_STYLE, lOldStytle )   End Sub