如何测量C中的时间间隔? [英] How do I measure a time interval in C?

问题描述

我想用 C 来测量时间，但我很难弄清楚，我想要的是这样的:

I would like to measure time in C, and I am having a tough time figuring it out, all I want is something like this:

• 启动计时器
• 运行一个方法
• 停止计时器
• 报告花费的时间(至少要精确到微量级)

任何帮助将不胜感激.

(我正在使用 mingw 在 windows 中编译)

(I am compiling in windows using mingw)

推荐答案

提供 1 微秒分辨率的高分辨率计时器是特定于系统的，因此您必须使用不同的方法在不同的操作系统平台上实现这一点.您可能有兴趣查看以下文章，该文章基于以下描述的函数实现了一个跨平台的 C++ 计时器类:

High resolution timers that provide a resolution of 1 microsecond are system-specific, so you will have to use different methods to achieve this on different OS platforms. You may be interested in checking out the following article, which implements a cross-platform C++ timer class based on the functions described below:

• [Song Ho Ahn - 高分辨率计时器][1]

Windows

Windows API 提供了极高分辨率的计时器函数:QueryPerformanceCounter()，它返回当前经过的滴答声，以及 QueryPerformanceFrequency()，它返回每个滴答声的数量第二个.

The Windows API provides extremely high resolution timer functions: QueryPerformanceCounter(), which returns the current elapsed ticks, and QueryPerformanceFrequency(), which returns the number of ticks per second.

示例:

#include <stdio.h>
#include <windows.h>                // for Windows APIs

int main(void)
{
    LARGE_INTEGER frequency;        // ticks per second
    LARGE_INTEGER t1, t2;           // ticks
    double elapsedTime;

    // get ticks per second
    QueryPerformanceFrequency(&frequency);

    // start timer
    QueryPerformanceCounter(&t1);

    // do something
    // ...

    // stop timer
    QueryPerformanceCounter(&t2);

    // compute and print the elapsed time in millisec
    elapsedTime = (t2.QuadPart - t1.QuadPart) * 1000.0 / frequency.QuadPart;
    printf("%f ms.
", elapsedTime);
}

Linux、Unix 和 Mac

对于基于 Unix 或 Linux 的系统，您可以使用 gettimeofday().该函数在sys/time.h"中声明.

For Unix or Linux based system, you can use gettimeofday(). This function is declared in "sys/time.h".

示例:

#include <stdio.h>
#include <sys/time.h>                // for gettimeofday()

int main(void)
{
    struct timeval t1, t2;
    double elapsedTime;

    // start timer
    gettimeofday(&t1, NULL);

    // do something
    // ...

    // stop timer
    gettimeofday(&t2, NULL);

    // compute and print the elapsed time in millisec
    elapsedTime = (t2.tv_sec - t1.tv_sec) * 1000.0;      // sec to ms
    elapsedTime += (t2.tv_usec - t1.tv_usec) / 1000.0;   // us to ms
    printf("%f ms.
", elapsedTime);
}

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