打印时间信息

gettimeofday() -- 获取当前时间(保存在结构体timeval中)

#include

#include

#include

int main(int argc, char * argv[]){

    struct timeval tv;                //(1)

    while(1){

        gettimeofday(&tv, NULL);      //(2)

        printf("time %u:%u\n", tv.tv_sec, tv.tv_usec);

        sleep(2);

    }

    return 0;

}

(1) struct--timeval

--------------------------------------------------

struct timeval {

    time_t      tv_sec;     /* seconds */

    suseconds_t tv_usec;    /* microseconds */

};

millisecond        毫秒

microsecond        微秒

timeval表示一个时间点，比如:

timeval.tv_sec = 1   (s)

timevat.tv_usec = 500 000 (μs)

1:500 = 1s500000μs = 1.5s

(2) gettimeofday()

--------------------------------------------------

int gettimeofday(struct timeval *tv, struct timezone *tz);

    The functions gettimeofday() and settimeofday() can get and set the time as well as a timezone. 

    The use of the timezone structure is obsolete; the tz argument should normally be specified as NULL.

(3) 运行结果:

--------------------------------------------------

time 1181788367:991487

time 1181788369:991602

表示睡眠2秒经过的精确时间为： 2s115μs

备注：

1秒＝1000毫秒，

1毫秒＝1000微秒，

1微妙＝1000纳秒，

1纳秒＝1000皮秒。

秒用s表现,毫秒用ms,微秒用μs表示，纳秒用ns表示，皮秒用ps表示。