How to save time Interval before is ends?

I'd suggest the following:-

1. Add these private fields to your form:

private DateTime lastTick;

private bool enterPressed;

2. In Form_Load or wherever you start the timer, add these lines:

lastTick = DateTime.Now;

enterPressed = false;

3. Change the code where you capture the pressing of the Enter key to this (it's assumed you only want to allow the user to press Enter once per 10 second interval);

if (e.KeyCode == Keys.Enter && !enterPressed)

{

enterPressed = true;

TimeSpan elapsed = DateTime.Now - lastTick;

ResponseTimeList.Add(elapsed.TotalSeconds);

}

4. Finally, add these lines to the timer_Tick eventhandler:

if(!enterPressed) ResponseTimeList.Add(10.0);

lastTick = DateTime.Now;

enterPressed = false;