Timer

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace _20120117_Timer
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btstart_Click(object sender, EventArgs e)
        {
            timer1.Start();
        }

        int sekunden = 0;
        private void timer1_Tick(object sender, EventArgs e)
        {
            sekunden++; // sekunden =sekunden +1;
            lbZeit.Text = Convert.ToString(sekunden);
        }

        private void btreset_Click(object sender, EventArgs e)
        {
            sekunden = 0;
            lbZeit.Text = Convert.ToString(sekunden);
        }

        private void btstop_Click_1(object sender, EventArgs e)
        {
            timer1.Stop();
        }
    }
}