timeval
DESCRIPTION The functions gettimeofday and settimeofday can get and set the time as well as a timezone. The tv argument is a timeval struct, as specified in <sys/time.h>:struct timeval { time_t tv_sec; /* seconds */ suseconds_t tv_usec; /* microseconds */ }; 其中返回的timeval值为Epoch（00:00:00 1970-01-01 UTC）到创建struct timeval时的时间，tv_sec为秒数部分，tv_usec为微秒数部分（10的-6次方秒）。比如当前程序运行的tv_sec为1244770435，tv_usec为442388，即当前时间距Epoch时间1244770435秒，442388微秒。测试代码如下： #include <stdio.h> #include <sys/time.h> #include <time.h> int gettimeofday(struct timeval *tv, struct timezone *tz); int main(int argc,char * argv[]){ struct timeval tv; while(1){ gettimeofday(&tv,NULL); printf("time %u:%u/n",tv.tv_sec,tv.tv_usec); sleep(2); } return 0; }
运行结果如下：time 1259471701:970193time 1259471703:971529time 1259471705:973225time 1259471707:974921
timespec/* POSIX.1b structure for a time value. This is like a `struct timeval' but has nanoseconds instead of microseconds. */struct timespec{ __time_t tv_sec; /* Seconds. */ long int tv_nsec; /* Nanoseconds. */};
与struct timeval 不同，将结构体内成员微秒变换成纳秒
