DESCRIPTION
The functions gettimeofday and settimeofday can get and set the time as
well as a timezone. The tv argument is atimevalstruct, as specified
in <sys/time.h>:
structtimeval{
time_t tv_sec; /* seconds */
suseconds_t tv_usec; /* microseconds */
};
其中对tv_usec的说明为时间的毫秒部分。 而在实际中，该函数以及Linux内核返回的timeval
类型的时间值，tv_usec代表的是微秒精度（10的－6次方秒）。
测试代码如下：
#include <stdio.h>
#include <sys/time.h>
#include <time.h>
int gettimeofday(structtimeval*tv, struct timezone *tz);
int main(int argc,char * argv[]){
structtimevaltv;
while(1){
gettimeofday(&tv,NULL);
printf("time %u:%u
",tv.tv_sec,tv.tv_usec);
sleep(2);
}
return 0;
}
返回结果为：
evil@dcenter:~/tmp$ ./a.out
time 1142077839:903605
time 1142077841:910129
time 1142077843:920155
time 1142077845:930180
time 1142077847:940205
time 1142077849:950231
time 1142077851:960256
time 1142077853:970280
time 1142077855:980307
time 1142077857:990331