测量 Windows C++ 的时间、毫秒或微秒
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/23615776/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Measure time, milliseconds or microseconds for Windows C++
提问by user3617694
How do you measure the execution time in milliseconds or microseconds in Windows C++?
在 Windows C++ 中，如何以毫秒或微秒为单位测量执行时间？
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.
我发现了许多方法一调用 time(NULL)，但它仅以秒为单位测量时间，而秒 clock() (clock_t) 测量 CPU 时间，而不是实际时间。
I found the function gettimeofday(Calendar time) mentioned in this paper: dropbox.com/s/k0zv8pck7ydbakz/1_7-PDF_thesis_2.pdf
我找到了这篇论文中提到的函数gettimeofday(Calendar time)：dropbox.com/s/k0zv8pck7ydbakz/1_7-PDF_thesis_2.pdf
This function is for Linux (compute time in milli and microseconds) and not Windows.
此函数适用于 Linux（以毫秒和微秒为单位计算时间）而不是 Windows。
I found an alternative to it for Windows: dropbox.com/s/ofo99b166l7e2gf/gettimeofday.txt
我找到了 Windows 的替代方法：dropbox.com/s/ofo99b166l7e2gf/gettimeofday.txt
And this may be relevant: stackoverflow.com/questions/1861294/how-to-calculate-execution-time-of-a-code-snippet-in-c
这可能是相关的：stackoverflow.com/questions/1861294/how-to-calculate-execution-time-of-a-code-snippet-in-c
回答by bames53
You can use the standard C++ <chrono>library:
您可以使用标准 C++<chrono>库：
#include <iostream>
#include <chrono>
// long operation to time
long long fib(long long 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();
long long input = 32;
long long result = fib(input);
auto end_time = std::chrono::high_resolution_clock::now();
auto time = end_time - start_time;
std::cout << "result = " << result << '\n';
std::cout << "fib(" << input << ") took " <<
time/std::chrono::milliseconds(1) << "ms to run.\n";
}
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: https://stackoverflow.com/a/15839862/365496
要记住的一件事是，使用<chrono>启用类型安全的通用计时代码，但要获得这种好处，您使用它的方式与使用愚蠢的、类型不安全的计时库略有不同，后者将持续时间和时间点存储在int. 这是一个答案，解释了一些特定的使用场景以及使用无类型库和使用 chrono 的最佳实践之间的区别：https: //stackoverflow.com/a/15839862/365496
The maintainer of Visual Studio's standard library implementation has indicatedthat the low resolution of high_resolution_clockhas been fixed in VS2015 via the use of QueryPerformanceCounter().
Visual Studio 标准库实现的维护者表示，high_resolution_clockVS2015 中已通过使用QueryPerformanceCounter().
回答by Darrin Cullop
You need to use the QPC/QPF APIs to get compute the execution time. Invoke the code you want to between calls to QueryPerformanceCounterand then use QueryPerformanceFrequencyto convert it from cycles to microseconds.
您需要使用 QPC/QPF API 来计算执行时间。在对QueryPerformanceCounter 的调用之间调用您想要的代码，然后使用QueryPerformanceFrequency将其从周期转换为微秒。
LARGE_INTEGER nStartTime;
LARGE_INTEGER nStopTime;
LARGE_INTEGER nElapsed;
LARGE_INTEGER nFrequency;
::QueryPerformanceFrequency(&nFrequency);
::QueryPerformanceCounter(&nStartTime);
SomethingToBeTimed();
::QueryPerformanceCounter(&nStopTime);
nElapsed.QuadPart = (nStopTime.QuadPart - nStartTime.QuadPart) * 1000000;
nElapsed.QuadPart /= nFrequency.QuadPart;
References: http://msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx
参考资料：http: //msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx
回答by MooseBoys
You're looking for QueryPerformanceCounterand related functions.
您正在寻找QueryPerformanceCounter和相关的功能。
