Go C # Precision Time timers

Original address: HTTP://BLOG.SINA.COM.CN/S/BLOG_699D3F1B01012VGB.HTML1 calls the GetTickCount in the win API

[DllImport ("kernel32")]
static extern uint GetTickCount ();

The number of milliseconds that have elapsed since the operating system started up to now, with a precision of 1 milliseconds, has been tested to find that the error is about 15MS

Disadvantage: The return value is uint and the maximum value is 2 of 32, so if the server is powered on for approximately 49 days, the return value obtained by the method will be zeroed

Usage:

123	uint s1 = GetTickCount(); Thread.Sleep(2719); Console.WriteLine(GetTickCount() - s1);  //单位毫秒

2 calling the timeGetTime recommendation in the win API

[DllImport ("winmm")]
static extern uint timeGetTime ();

Commonly used in multimedia timers, similar to GetTickCount, and also returns the number of milliseconds the operating system has been booted to now, with a precision of 1 milliseconds.

The general default accuracy is more than 1 milliseconds (different operating systems differ), you need to call Timebeginperiod and timeendperiod to set the precision

[DllImport ("winmm")]
static extern void Timebeginperiod (int t);
[DllImport ("winmm")]
static extern void Timeendperiod (int t);

Disadvantage: As with GetTickCount, the maximum number of digits is limited by the return value.

Usage:

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12345

timeBeginPeriod(1); uint start = timeGetTime(); Thread.Sleep(2719); Console.WriteLine(timeGetTime() - start);  //单位毫秒 timeEndPeriod(1);

3 How to call the. NET self-System.Environment.TickCount

Gets the number of milliseconds that have elapsed since the system started. Anti-compilation guesses that it may also be the gettickcount of the call, but its return value is int, and the return value in the prototype of GetTickCount and timeGetTime method is a DWORD, corresponding to the UINT in C #. NET what else do you do with System.Environment.TickCount?
Disadvantage: As with GetTickCount, the maximum number of digits is limited by the return value.

Usage:

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123	intaa = System.Environment.TickCount;Thread.Sleep(2719);Console.WriteLine(System.Environment.TickCount - aa);//单位毫秒

Note : After testing, it is found that GetTickCount, System.Environment.TickCount can also be used timebeginperiod and timeendperiod to set the accuracy, the highest accuracy can be increased to 1 milliseconds. I don't know what the reason is.

4 calling the QueryPerformanceCounter in the win API

[DllImport ("kernel32.dll")]
static extern bool QueryPerformanceCounter (ref   long Lpperformancecount);

The value used to get a high-precision timer (if such a timer exists). Microsoft's explanation of this API is the value of a counter growth per second.
If the installed hardware does not support a high-precision timer, the function returns false and needs to mate with another API function, QueryPerformanceFrequency.

[DllImport ("kernel32")]
static extern bool QueryPerformanceFrequency (ref long performancefrequency);

QueryPerformanceFrequency returns the frequency of hardware-supported high-precision counters, and returns False if the installed hardware does not support high-precision timers.

Usage:

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long a = 0; QueryPerformanceFrequency(ref a); long b = 0, c = 0; QueryPerformanceCounter(ref b); Thread.Sleep(2719); QueryPerformanceCounter(ref c); Console.WriteLine((c - b) / (decimal)a);  //单位秒

The accuracy is one out of 10,000 seconds. And because it is a long type, there is no problem with the above few API bits.

Cons: In an article to see, the API in the energy-saving mode when the results are slow, overclocking mode is fast, and battery and power when the effect is not the same (notebook)
Original address: http://delphi.xcjc.net/viewthread.php?tid=1570
Without overclocking and other tests, if true, the API's results may not be allowed.

5 Recommended for System.Diagnostics.Stopwatch class using. Net

The stopwatch counts the ticks in the base timer mechanism to measure elapsed time. If the installed hardware and operating system support counters for high-resolution performance, the Stopwatch class will use this counter to measure elapsed time, otherwise the Stopwatch class will use system counters to measure elapsed time. Use Frequency and ishighresolution two static fields to determine the accuracy and resolution of the Stopwatch timing.

In fact it is the QueryPerformanceCounter, queryperformancefrequency two WINAPI package, if the hardware supports high precision, call QueryPerformanceCounter, If not supported, use Datetime.ticks to calculate.

Usage:

Stopwatch sw = new Stopwatch(); sw.Start(); Thread.Sleep(2719); sw.Stop(); Console.WriteLine(sw.ElapsedTicks / ( decimal )Stopwatch.Frequency);

6 with DateTime.Now.Ticks

http://www.cnblogs.com/csharp4/archive/2010/07/24/1784094.html

1 ticks represent 100 nanoseconds, 1 milliseconds equals 10,000 ticks, which means 1 seconds equals 1E7 ticks.

Any one of the DateTime variables has a ticks property that represents the ticks value of the interval from 12:00:00 midnight, January 1, and 0001 to the current time value.

Using the method above, the most accurate, should be accurate to 1tick, that is, 100 nanoseconds.

Go C # Precision Time timers