struct-timeval 用法

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

例子：

#include <stdio.h>
#include <sys/time.h>
#include <time.h>
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;    
   suseconds_t tv_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, struct timezone *tz);