c - 在C中计算每秒平均值

Question

我有一个递增的整数值，并想找到该整数的每秒平均值。我知道除非您执行特定且复杂的操作，否则 C 中不存在计时器 [我是 C 新手] 有没有更简单的方法可以做到这一点？最好在进行计算时重置该值，以免内存中存在如此大的数字，因为该应用程序将运行很长时间。

Answer 1

I think you will want to include time.h, and use some of its functions and structs (this is actually not a bad way of learning the basics of C). There is an explanation and a few examples here.

If you need sub-second accuracy I suggest you use clock_gettime(), which will give you nanosecond resolution.

Here is an example:

#include <stdio.h>
#include <time.h>

struct timespec diff(struct timespec start, struct timespec end);

int main()
{
    struct timespec time1, time2, timeDiff;
    int temp, i;

    // Get the start time
    clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &time1);

    // Do some work
    for (i = 0; i< 242000000; i++)
        temp+=temp;

    // Get the end time
    clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &time2);

    // Calculate the difference
    timeDiff = diff(time1,time2);

    printf("%d.%d\n", timeDiff.tv_sec, timeDiff.tv_nsec);
    return 0;
}

struct timespec diff(struct timespec start, struct timespec end)
{
    struct timespec temp;
    if ((end.tv_nsec-start.tv_nsec)<0) {
        temp.tv_sec = end.tv_sec-start.tv_sec-1;
        temp.tv_nsec = 1000000000+end.tv_nsec-start.tv_nsec;
    } else {
        temp.tv_sec = end.tv_sec-start.tv_sec;
        temp.tv_nsec = end.tv_nsec-start.tv_nsec;
    }
    return temp;
}

You will need to compile with something like:

gcc -o timetest timetest.c -lrt

The -lrt part of the command tells the C linker to link to the Realtime library, which contains the definition of clock_gettime().

Answer 2

您可以只使用gettimeofday()来获取时间值。您需要存储一个这样的读数，以便您可以将最近的读数与旧的读数进行比较，并计算出它们之间的时间。如果您以秒为单位执行此操作，则可以将整数除以该间隔并获得每秒的平均值。