Is it ever OK to use Environment.TickCount
to calculate time spans?
int start = Environment.TickCount; // Do stuff int duration = Environment.TickCount - start; Console.WriteLine("That took " + duration " ms");
Because TickCount
is signed and will rollover after 25 days (it takes 50 days to hit all 32 bits, but you have to scrap the signed bit if you want to make any sense of the math), it seems like it's too risky to be useful.
I'm using DateTime.Now
instead. Is this the best way to do this?
DateTime start = DateTime.Now; // Do stuff TimeSpan duration = DateTime.Now - start; Console.WriteLine("That took " + duration.TotalMilliseconds + " ms");
The TickCount property cycles between Int32. MinValue, which is a negative number, and Int32. MaxValue once every 49.8 days. This code sample removes the sign bit to yield a nonnegative number that cycles between zero and MaxValue once every 24.9 days.
Tick Counter is a feature available for charts using Tick aggregation. This feature shows dynamic tick information for the last bar on chart, which includes the number of ticks since the open and the number of ticks until completion.
Environment.TickCount is based on GetTickCount() WinAPI function. It's in milliseconds But the actual precision of it is about 15.6 ms. So you can't measure shorter time intervals (or you'll get 0)
Note: The returned value is Int32, so this counter rolls over each ~49.7 days. You shouldn't use it to measure such long intervals.
DateTime.Ticks is based on GetSystemTimeAsFileTime() WinAPI function. It's in 100s nanoseconds (tenths of microsoconds). The actual precision of DateTime.Ticks depends on the system. On XP, the increment of system clock is about 15.6 ms, the same as in Environment.TickCount. On Windows 7 its precision is 1 ms (while Environemnt.TickCount's is still 15.6 ms), however if a power saving scheme is used (usually on laptops) it can go down to 15.6 ms as well.
Stopwatch is based on QueryPerformanceCounter() WinAPI function (but if high-resolution performance counter is not supported by your system, DateTime.Ticks is used)
Before using StopWatch notice two problems:
You can evaluate the precision on your system with simple test:
static void Main(string[] args) { int xcnt = 0; long xdelta, xstart; xstart = DateTime.UtcNow.Ticks; do { xdelta = DateTime.UtcNow.Ticks - xstart; xcnt++; } while (xdelta == 0); Console.WriteLine("DateTime:\t{0} ms, in {1} cycles", xdelta / (10000.0), xcnt); int ycnt = 0, ystart; long ydelta; ystart = Environment.TickCount; do { ydelta = Environment.TickCount - ystart; ycnt++; } while (ydelta == 0); Console.WriteLine("Environment:\t{0} ms, in {1} cycles ", ydelta, ycnt); Stopwatch sw = new Stopwatch(); int zcnt = 0; long zstart, zdelta; sw.Start(); zstart = sw.ElapsedTicks; // This minimizes the difference (opposed to just using 0) do { zdelta = sw.ElapsedTicks - zstart; zcnt++; } while (zdelta == 0); sw.Stop(); Console.WriteLine("StopWatch:\t{0} ms, in {1} cycles", (zdelta * 1000.0) / Stopwatch.Frequency, zcnt); Console.ReadKey(); }
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