stopwatch

public partial class Form1 : Form
{
Stopwatch s;
Timer t1;
public Form1()
{
t1 = new Timer(); ;
s = new Stopwatch();
t1.Tick += new EventHandler(tick);
InitializeComponent();
s.Reset();
t1.Start();

}

private void button1_Click(object sender, EventArgs e)
{
s.Stop();


}

public void tick(object sender, EventArgs e)
{
textBox1.Text = s.Elapsed.ToString();

}

private void button2_Click(object sender, EventArgs e)
{
s.Reset();
listBox1.Items.Clear();

}

private void button3_Click(object sender, EventArgs e)
{
s.Start();
}

private void button4_Click(object sender, EventArgs e)
{
listBox1.Items.Add(s.Elapsed.ToString());
}
}