The MetaTrader 4/5 standard timer is based on the system timer call and can therefore work inaccurately. We can check this by running the following simple Expert Advisor:

input int Timer = 1000; // The number of milliseconds for the timer to trigger    #define TOSTRING(A) #A + " = " + (string)(A) + " ms.\n"    const bool Init = EventSetMillisecondTimer(Timer);    // Shows the current timer error and its average value as a comment on a chart  void OnTimer()  {    static ulong StartTime = 0;    static int Count = 0;    static int Sum = 0;      if (StartTime)    {      const int RunTime = (int)(GetMicrosecondCount() - StartTime) / 1000;      const int Error = RunTime - Timer * Count;        Sum += Error;        Comment(TOSTRING(Timer) + TimeToString(RunTime / 1000, TIME_SECONDS) + "\n" +              TOSTRING(Error) + TOSTRING((double)Sum / Count));    }    else      StartTime = GetMicrosecondCount();      Count++;  }  

In the chart comment (the upper left corner) it shows how the timer lag grows:

The screenshot shows that in just a minute, the second timer creates a lag of more than a second. Moreover this lag grows over time!

This library allows increasing the accuracy of the standard timer for any Expert Advisor/indicator. For this purpose, the following line should be added at the beginning of the code:

#include <AccurateTimer.mqh> // Increasing the accuracy of the standard timer

After that the following comment will be shown:

After ten minutes of operation, the average deviation from the ideal (theoretical) timer is ~1 ms, and the error will not grow.

It is always good to have an accurate timer. But for some tasks it is a must. For example, a second timer synchronized with the trade server time.

This cross-platform library is compatible with all Expert Advisors/indicators, which use the standard timer (OnTimer). It does not affect the execution speed in the strategy tester.

Increase the accuracy of your existing and new programs in just one line!