问c#中的停止声音

EN

private SoundPlayer player;

private void guna2Button1_Click(object sender, EventArgs e)
{
    if (guna2CheckBox2.Checked && guna2CheckBox1.Checked)
    {
        MessageBox.Show("Please Choose One Box only");
    }
    else
    {
        OpenFileDialog ofd = new OpenFileDialog();
        ofd.InitialDirectory = Environment.CurrentDirectory;
        ofd.ShowDialog();

        player = new SoundPlayer(ofd.FileName);
        player.Play();
    }
}

private void guna2Button2_Click(object sender, EventArgs e)
{
    //Check if the player is null (not defined yet), otherwise this could cause a NullReferenceException
    if (player != null) {
        player.Stop();
    }
}