Wait exactly one second with Math.Pow

Question

I wonder how can I wait exactly one second using a special function called WastedTime which takes one argument MaxDelay and inside the method it does some weird calculations causing the program to waste time with calculations. I want to waste exactly one second. After a lot of attempts, 360,000,00 seems to work. But how can I validate that the program sleep for one second?

More body performance in a loop will waste more computation time - resulting in a delay between prints. Write the full method that accepts the MaxDelay value as a parameter and place it in the main program call it that way Let the clock print a line every second. Check what is the most appropriate value for MaxDelay to run the watch accurately. Try running for a minute And compare to a real watch.

For now it seems like it actually wait one second but I wonder how can I make sure it does?

using System;

class Program
{
    static void Main(string[] args)
    {
        const int MaxDelay = 36000000; // (360,000,00)
        for (int h = 0; h < 24; h++)
            for (int m = 0; m < 60; m++)
                for (int s = 0; s < 60; s++)
                {
                    WasteTime(MaxDelay);
                    Console.WriteLine(h + ":" + m + ":" + s);
                }
    }
    static void WasteTime(int MaxDelay)
    {
        double temp = 0;
        for (int delay = 1; delay <= MaxDelay; delay++)
            temp = Math.Pow(Math.PI, 2);
    }
}

Expected Output

0:0:0
// .. one second
0:0:1
// .. second
0:0:2

Note: Please leave the WasteTime as is

Answer 1

If you want to waste some exact time on a machine, your code has to perform a measurement how many times can something simple be computed in a smaller time, then upscale to the desired time and check if this matches.

So here is some sketch:

• What time is it now?
• Call your WasteTime() 1 thousans times
• What time is it now?
• How many time elapsed from the above given dates?
• If e.g. it took 37 msec to perfom that task, note this timespan into a variable
• If you like to wait 5 secs, divide this wait time with your single execution timespan.
• Execute your simple task this many times.

Be aware that your numbers will always change, depending on the used computer, but also if you run a debug or release version. Depending on your simple task, the compiler could see, that you do nothing and optimize your code away.

Answer 2

You would need to time how long one loop takes, for this you should use a stopwatch since this is the way to accurately measure time:

        WasteTime(1); // Warmup, ensure the method is compiled
        int timingLoopCount = 100000000;
        var sw = Stopwatch.StartNew();
        WasteTime(100000000); // Time some long loop
        sw.Stop();
        var loopsPerSecond = timingLoopCount * TimeSpan.TicksPerSecond / sw.Elapsed.Ticks;
        Console.WriteLine("Loops Per Second: " + loopsPerSecond);

You should never do this!

Since the WasteTime function does not return any result and have no side effects, the jitter could decide to just omit the function call, causing infinite/undefined number of loops per second. There are many other issues with such approach, like drift caused by varying load or power budget on the system.

This was somewhat common on older systems. On startup the system would loop some fixed amount of times and check how long it took. This became a common source of issues when computers got fast enough to complete all the loops faster than the resolution of the timer.

What you should use is:

• DateTime for showing the system time
• Stopwatch to measure time intervals with high precision
• Timer for reoccurring events, like updating a clock.
• Media timer for high precission reoccuring events (like video playback)