C# TextBox只能输入数字（不包括点号）

private void TxtBox_KeyPress(object sender, KeyPressEventArgs e) {     e.Handled = !char.IsNumber(e.KeyChar);     if (!e.Handled)     {         (sender as TextBox).Tag = (sender as TextBox).Text;     }     else if(char.IsControl(e.KeyChar))     {         e.Handled = !e.Handled;     } }