Question

I have a timer that runs every second, the code is bellow:

    public MainWindow()
    {
        InitializeComponent();

        DispatcherTimer timer = new DispatcherTimer();
        timer.Interval = TimeSpan.FromMilliseconds(1000);
        timer.Tick += new EventHandler(someEventHandler);
        timer.Start();
    }

    private void someEventHandler(Object sender, EventArgs args)
    {
        TVMonitor TVMonitor = new TVMonitor();
        if (TVMonitor.NeedsTurningOn())
        {
            Console.WriteLine("on");
            TVCOM.SendCommand(SettingManager.GetTVCode("on") + Environment.NewLine);
        }
    }

In the function NeedsTurningOn() I have the following:

    public bool NeedsTurningOn()
    {
        var turnon = (from settings in context.SystemSettings
                      where settings.SystemSettingName == "TVOnTime"
                      select settings).First();
        if (turnon.SystemSettingValue == String.Empty)
        {
            return false;
        }

        DateTime date = Convert.ToDateTime(turnon.SystemSettingValue);
        Console.WriteLine("Turnontime: " + date);
        Console.WriteLine("currenttim: " + DateTime.Now);
        if (date != DateTime.Now)
        {
            Console.WriteLine("false");
            return false;
        }
        else
        {
            Console.WriteLine("true");
            return true;
        }
    }

Now in the console which I am using for debugging, I have the following output:

...
Turnontime: 11/04/2011 14:05:10
currenttim: 11/04/2011 14:05:07
false
Turnontime: 11/04/2011 14:05:10
currenttim: 11/04/2011 14:05:08
false
Turnontime: 11/04/2011 14:05:10
currenttim: 11/04/2011 14:05:09
false
Turnontime: 11/04/2011 14:05:10
currenttim: 11/04/2011 14:05:10
false
Turnontime: 11/04/2011 14:05:10
currenttim: 11/04/2011 14:05:11
false
Turnontime: 11/04/2011 14:05:10
currenttim: 11/04/2011 14:05:12
false
...

Why is this still firing off a false instead of true once the date is the same?

Answer 1

You only compare the times every second – the milliseconds will still be different (especially assuming the turn-on time you compare to most likely doesn’t use milliseconds). To compare in a second resolution you could do something like this:

DateTime currentTime = DateTime.Now;
currentTime = currentTime.AddMilliseconds(-currentTime.Millisecond);