????(6) struct tm???????????????????????
struct tm
{
int tm_sec; /* seconds */
int tm_min; /* minutes */
int tm_hour; /* hours */
int tm_mday; /* day of the month */
int tm_mon; /* month */
int tm_year; /* year */
int tm_wday; /* day of the week */
int tm_yday; /* day in the year */
int tm_isdst; /* daylight saving time */
};
struct tm* gmtime(const time_t *timep);
struct tm* localtime(const time_t *timep);
time_t mktime(struct tm *tm);
????gmtime??localtime?????????????????????????????????????????α?????????????????.
???????: ????????????????????????? ???????????汾?? ???????_r??汾 -- gmtime_r?? localtime_r?? mktime_r.
???????? ??????
????????????????У?sleep()??usleep()??nanosleep()??select()??pselect().
????unsigned int sleep(unsigned int seconds);
????void usleep(unsigned long usec);
????int nanosleep(const struct timespec *req?? struct timespec *rem);
????int select(int n?? fd_set *readfds?? fd_set *writefds?? fd_set *exceptfds??struct timeval *timeout);
????int pselect(int n?? fd_set *readfds?? fd_set *writefds?? fd_set *exceptfds?? const struct timespec *timeout?? const sigset_t *sigmask);
????alarm?????????????????????????????????????
?????????????????????????????????2?sleep????????????usleep/select?????????????nanosleep??pselect??????????????
?????????????У?linux???nanosleep??alarm???????????????????????????linux??????????????????????????????man nanosleep????????????????man?????????????Linux/i386????10 ms ??Linux/Alpha????1ms??