linux clock单位

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

int main() {
    clock_t start, end;
    double cpu_time_used;

    start = clock();

    // 模拟一些耗时操作
    for (int i = 0; i < 1000000; i++) {
        // 做一些计算
    }

    end = clock();
    cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;

    printf("程序执行时间: %f 秒\n", cpu_time_used);
    return 0;
}

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

int main() {
    struct timespec start, end;
    double elapsed;

    clock_gettime(CLOCK_MONOTONIC, &start);

    // 模拟一些耗时操作
    for (int i = 0; i < 1000000; i++) {
        // 做一些计算
    }

    clock_gettime(CLOCK_MONOTONIC, &end);
    elapsed = (end.tv_sec - start.tv_sec) + (end.tv_nsec - start.tv_nsec) / 1000000000.0;

    printf("程序执行时间: %f 秒\n", elapsed);
    return 0;
}

#ifdef _WIN32
#include <windows.h>
#else
#include <time.h>
#endif

double get_time() {
#ifdef _WIN32
    LARGE_INTEGER frequency;
    QueryPerformanceFrequency(&frequency);
    LARGE_INTEGER now;
    QueryPerformanceCounter(&now);
    return (double)now.QuadPart / frequency.QuadPart;
#else
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return ts.tv_sec + ts.tv_nsec * 1e-9;
#endif
}