Private Sub TextBox1_KeyPress(ByVal sender As System.Object,ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
    Dim allowedChars As String = "0123456789"
    If allowedChars.IndexOf(e.KeyChar) = -1 Then
        ' Invalid Character
        e.Handled = True
    End If
End Sub

但是……用户无法使用退格按钮删除数字.那我该怎么办？