Question

How to make a timer which forces the application to close at a specified time in C#? I have something like this:

void  myTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
    if (++counter == 120)
        this.Close();
}

But in this case, the application will be closed in 120 sec after the timer has ran. And I need a timer, which will close the application for example at 23:00:00. Any suggestions?

Answer 1

The first problem you have to fix is that a System.Timers.Timer won’t work. It runs the Elapsed event handler on a thread-pool thread, such a thread cannot call the Close method of a Form or Window. The simple workaround is to use a synchronous timer, either a System.Windows.Forms.Timer or a DispatcherTimer, it isn’t clear from the question which one applies.

The only other thing you have to do is to calculate the Interval property value for the timer. That’s fairly straight-forward DateTime arithmetic. If you always want the window to close at, say, 11 o’clock in the evening then write code like this:

    public Form1() {
        InitializeComponent();
        DateTime now = DateTime.Now;  // avoid race
        DateTime when = new DateTime(now.Year, now.Month, now.Day, 23, 0, 0);
        if (now > when) when = when.AddDays(1);
        timer1.Interval = (int)((when - now).TotalMilliseconds);
        timer1.Start();
    }
    private void timer1_Tick(object sender, EventArgs e) {
        this.Close();
    }