Time

/*函数time头文件*/
#include <time.h>

#include <stdio.h>

int main(void)
{
    time_t timep;

    time(&timep);
    printf("UTC time: 0x%08x\n", timep);

    timep = time(NULL);
    printf("UTC time: 0x%08x\n", timep);

    return 0;
}

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

int main(void)
{
    time_t timep;
    struct tm *tblock;

    time(&timep);
    printf("ctime/timep is %s\n", ctime(&timep));

    printf("asctime is %s\n", asctime(gmtime(&timep)));

    tblock = localtime(&timep);
    printf("localtime is :%s\n", asctime(tblock));
    printf("localtime is:%s\n", ctime(&timep));
    return 0;
}

#include <time.h>
/*函数gettimeofday和settimeofday的头文件*/
#include <sys/time.h>
#include <stdio.h>

void delay()
{
    unsigned int i, j;
    double y;
    for (i = 0; i < 1000; i++)
        for (j = 0; j < 1000; j++)
            y = i / (j + 1); // 耗时操作
}

main()
{
    struct timeval tpstart, tpend;
    float timeuse;

    gettimeofday(&tpstart, NULL); // 记录开始时间
    delay();

    gettimeofday(&tpend, NULL); // 记录结束时间

    timeuse = 1000000 * (tpend.tv_sec - tpstart.tv_sec) +
              tpend.tv_usec - tpstart.tv_usec; // 计算差值
    timeuse /= 1000000;

    printf("Used Time:%f\n", timeuse);
}