测量Windows C ++的时间，毫秒或微秒 [英] Measure time, milliseconds or microseconds for Windows C++

问题描述

如何在Windows C ++中测量执行时间（以毫秒或微秒为单位）？

How do you measure the execution time in milliseconds or microseconds in Windows C++?

我发现很多方法一个调用时间

I found many method one calling time(NULL), but it measures time in seconds only and the seconds clock() (clock_t) measure CPU time, not the actual time.

我发现本文中提到的函数gettimeofday（日历时间）：
dropbox.com/s/k0zv8pck7ydbakz/1_7-PDF_thesis_2.pdf

I found the function gettimeofday(Calendar time) mentioned in this paper: dropbox.com/s/k0zv8pck7ydbakz/1_7-PDF_thesis_2.pdf

此函数适用于Linux（计算时间单位为毫秒和微秒），而不是Windows。

This function is for Linux (compute time in milli and microseconds) and not Windows.

我找到了Windows的替代方法：
dropbox.com/s/ofo99b166l7e2gf/gettimeofday.txt

I found an alternative to it for Windows: dropbox.com/s/ofo99b166l7e2gf/gettimeofday.txt

这可能是相关的：stackoverflow.com/questions/1861294/how-to-calculate-execution-time-of-a-code-snippet-in-c

And this may be relevant: stackoverflow.com/questions/1861294/how-to-calculate-execution-time-of-a-code-snippet-in-c

推荐答案

您可以使用标准C ++ < chrono> 图书馆：

You can use the standard C++ <chrono> library:

#include <iostream>
#include <chrono>

// long operation to time
int fib(int n) {
  if (n < 2) {
    return n;
  } else {
    return fib(n-1) + fib(n-2)
  }
}

int main() {
  auto start_time = std::chrono::high_resolution_clock::now();

  fib(12);

  auto end_time = std::chrono::high_resolution_clock::now();
  auto time = end_time - start_time;

  std::cout << "fib(100) took " <<
    std::chrono::duration_cast<std::chrono::microseconds>(time).count() << " to run.\n";
}

要记住的一件事是使用 ; chrono> 启用类型安全的通用时序代码，但是为了获得这样的好处，你使用它有点不同于使用哑，类型不安全的时序库，存储持续时间和时间点在类型如 int 。以下是解释某些特定使用场景以及使用非类型库和使用chrono的最佳做法之间的差异的解答： http://stackoverflow.com / a / 15839862/365496

One thing to keep in mind is that using <chrono> enables type safe, generic timing code but to get that benefit you have use it a bit differently than you would use dumb, type-unsafe timing libraries that store durations and time points in types like int. Here's an answer that explains some specific usage scenarios and the differences between using untyped libraries and best practices for using chrono: http://stackoverflow.com/a/15839862/365496

Visual Studio标准库实施的维护者已指示在VS2015中已经修复了 high_resolution_clock 的低分辨率使用 QueryPerformanceCounter（）。

The maintainer of Visual Studio's standard library implementation has indicated that the low resolution of high_resolution_clock has been fixed in VS2015 via the use of QueryPerformanceCounter().

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