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

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

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

    structtimeval tv;                //(1)
    while(1){
        gettimeofday(&tv,NULL);      //(2)
        printf("time%u:%u\n", tv.tv_sec, tv.tv_usec);
        sleep(2);
    }
    return0;

}

(1) struct--timeval
--------------------------------------------------
struct timeval {
    time_t      tv_sec;    
    suseconds_ttv_usec;   
};
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, structtimezone *tz);

    Thefunctions gettimeofday() and settimeofday() can get and set the time as well asa timezone.
    Theuse of the timezone structure is obsolete; the tz argument shouldnormally be specified as NULL.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