C++11 timer! delicious

One, foreword

In the process of writing a program, sometimes we need to test the execution time of our program statement, there are a lot of libraries to provide us to use, there has been no good cross-platform library can provide; And generally this kind of code is also by our programmer to call the system library, but often there will be insufficient accuracy and does not support cross-platform problems;

Here he comes… Here he comes. , he stepped on the colorful clouds come; “He” is the chrono library introduced in boost in C++11; He can achieve high precision clock, can do nanosecond;

Second, the chrono library

In C++11, is a time-related header file in the standard template library. All functions and class templates in this header are defined in the STD ::chrono namespace;

Here we mainly introduce two points of time and clock:

The general timer is the count from a certain point in time, and then to a certain point in time, is commonly called the time;

Time points:

template <class Clock, class Duration = typename Clock::duration>
  class time_point;
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STD ::chrono::time_point indicates a specific time

The first template parameter Clock is used to specify the Clock to be used. There are three types of clocks in the standard library:

System_clock: a real-time calendar clock that is currently system-wide (that is, consistent across processes)
Steady_clock: a dimension clock implemented by the current system whose ticks are uniform (equal in length).
High_resolution_clock: a high-resolution clock implemented by the current system.

The second template function argument is used to represent the unit of time (specialized STD ::chrono::duration<>)

Each point in time has a timestamp, the origin of time. The Unix timestamp used in chrono library is 00:00, January 1, 1970. So time_point is the length of time (duration) from the epoch.

Three, practice

Knowing these, we go to the beginning of the high-precision timer:

#ifndef _TimerClock_hpp_
#define _TimerClock_hpp_

#include <iostream>
#include <chrono>

using namespace std;
using namespace std::chrono;

class TimerClock
{
public:
 TimerClock()
 {
  update();
 }

 ~TimerClock()
 {
 }

 void update() { _start = high_resolution_clock::now(); } // get the second doublegetTimerSecond()
 {
  returnGetTimerMicroSec () * 0.000001; } // get a millisecond doublegetTimerMilliSec()
 {
  returnGetTimerMicroSec () * 0.001; } // get subtle long longgetTimerMicroSec() {// The current clock minus the start clock countreturn duration_cast<microseconds>(high_resolution_clock::now() - _start).count();
 }
private:
 time_point<high_resolution_clock>_start;
};

#endif
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Testing:

#include "TimerClock.hpp"

int main()
{
 TimerClock TC;
 int sum = 0;
 TC.update();
 for (int i = 0; i > 100000; i++)
 {
  sum++;
 }
 cout << "cost time:" << TC.getTimerMilliSec() <<"ms"<< endl;
 cout << "cost time:" << TC.getTimerMicroSec() << "us" << endl;

 return 0;
}
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Results:

Such high-precision tests can be used in our project code to calculate the time consuming of our program and optimize it.

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C++11 timer! delicious