Counting the execution time of a Task

[NickMak]

Hello,
I am checking out this simple piece of code:

private void button1_Click(object sender, EventArgs e)
        {
            Stopwatch sw = Stopwatch.StartNew();
 
            Task Task1 = Task.Factory.StartNew(() =>
                {
                    Console.WriteLine("Task1 started in : "+ " "+sw.ElapsedMilliseconds);
                    Thread.Sleep(4000);
                    Console.WriteLine("Task1 finished in : " + " " + sw.ElapsedMilliseconds);
                }
                );
        }

and the results are :
Task1 started in : 2 in milliseconds
Task1 finished in : 4015 in milliseconds.
The problem is, that if i count the time with an external device, just like the timer of my watch or my cellphone s,
the total time is 4,8 or 4,9 seconds, which i wouldn t expect that to happen.
The first thing i ve thought, is that it takes the ThreadPool about 800msec or 1 sec to create the thread so as
to execute this task, but even if it is so, shouldn t the stopwatch count the time precisely?
So , why is there a deviation between an external timer and the stopwatch ?
Thanx in advance.

[Rabbit]

Because your human hands sttempting to precisely time the execution is slower and less accurate than the computer. The results are correct.