C#

private void tree (string optional_parameter)
{
...
}

tree();

    ServiceController controller = new ServiceController("not existing service");
    try
    {
        if (controller.Status == ServiceControllerStatus.Running)
        {
            // do something
        }
    }
    catch (InvalidOperationException ex)
    {
        // come here when service name does not exist
    }
}

private void PlayList_CellClick(object sender, MouseEventArgs e)
    {
        if(e.Button == MouseButtons.Right)
        {
            Point loc = this.PointToScreen(new Point(e.X, e.Y));

            int index = PlayList.HitTest(e.X, e.Y).RowIndex;

            PlayListMenu.Show(loc.X, loc.Y);
        }
    }

BinaryWriter bw = new BinaryWriter(new FileStream(textbox1.Text, FileMode.Create,FileAccess.Write,FileShare.Write));
BinaryWriter bw1 = new BinaryWriter(new FileStream(textbox1.Text, FileMode.Open));