Time difference is zero in second calculation of division in c#

Question

I need to calculate the time difference faken for division most accurately in nano seconds. Please tell me to do this.

At Present i'm using a lower accuracy method in which the problem is that : when the first calculation is performed it shows 87 milliseconds or 65 milliseconds as answer. But when the function is called again second time or more, it only show 0 milliseconds.

The code is :

long startTick = DateTime.Now.Ticks;
double result = (double)22 / 7;
result = System.Math.Round(result, digit);                
long endTick = DateTime.Now.Ticks; 
long tick = endTick - startTick;
double milliseconds = tick / TimeSpan.TicksPerMillisecond;
time.Text = result + "\nThe division took " + milliseconds + " milliseconds to complete.";

digit is the parameter of function which is variable. No matter what the value of digit is the milliseconds value remains 0 after first calling of function....

Please suggest more accurate way in which calling the same function with different decimal digits will result in different time interval in c# for windows Phone.

I think the memory flush should be done before and after each calculation. But i dont know how to do this.

I don't like this tick method personally for accuracy. I've tried stopwatch also but its not working. Please suggest another method best suited in my case. I want result like : 0.0345 or 0.0714 seconds.

Thanks

Answer 1

You are performing integer division on this line:

double milliseconds = tick / TimeSpan.TicksPerMillisecond;

Even though you are declaring it as a double, a long divided by a long will truncate the decimal. You are better off doing:

double milliseconds = (double)tick / TimeSpan.TicksPerMillisecond;

Or better yet, just ditch the tick stuff all together:

DateTime start = DateTime.Now;
double result = (double)22 / 7;
result = System.Math.Round(result, digit);                
DateTime end = DateTime.Now;
double milliseconds = (end - start).TotalMilliseconds;
time.Text = result + "\nThe division took " + milliseconds + " milliseconds to complete.";

You won't be able to get micro or nano level precision, but you will get millisecond precision with a margin of error.

You still may get zero, however. You are trying to time how long a simple division operation takes. You could do millions of division operations in less than a second. You may want to do it 1,000,000 times, then divide the result by a 1,000,000:

DateTime start = DateTime.Now;
for (var i = 0; i < 1000000; i++)
{
    double result = (double)22 / 7;
    result = System.Math.Round(result, digit);
}
DateTime end = DateTime.Now;
double milliseconds = (end - start).TotalMilliseconds / 1000000;

This still won't be completely realistic, but should get you an actual number.

Answer 2

由于您的时间以滴答作响，因此只需乘以分母即可提高分辨率：

double microseconds = tick / (TimeSpan.TicksPerMillisecond * 1000.0);

Answer 3

Why are you not using StopWatch Class to do your time calulation. It is meant to the calculate the time the you want .. Here is a link for your reference.

http://msdn.microsoft.com/en-us/library/system.diagnostics.stopwatch.aspx

Answer 4

//if you want to get the full milliseconds you could also do something like this.

dateStartTime = Convert.ToDateTime(DateTime.Now.TimeOfDay.ToString());
//then where you end the code do this
dateEndTime = Convert.ToDateTime(DateTime.Now.TimeOfDay.ToString());
ddateDuration = (TimeSpan)(dateEndTime - dateStartTime);
then to display out what you are actually looking for in terms of miliseconds do
Console.WriteLine(ddateDuration.ToString().Substring(0, 8)); 
// or some other method that you are using to display the results