[STL] C ++ language ctime Library

1. Type
Clock_t: it is a long type, used to record the number of clock timing units in a period of time, that is, the CPU running unit time.
Size_t: defined in the Standard C library. It should be an unsigned int and a long unsigned int in a 64-bit system.
Time_t: the number of seconds that have elapsed since 00:00:00, January 1, January 1, 1970 to this time point.
Struct TM {
Int tm_sec;/* Second-value range: [0, 59] */
Int tm_min;/* minute-value range: [0, 59] */
Int tm_hour;/* hour-value range: [0, 23] */
Int tm_mday;/* date in a month-value range: [] */
Int tm_mon;/* month (from January 1, 0 represents January 1,)-value range: [] */
Int tm_year;/* year, whose value is equal to the actual year minus 1900 */
Int tm_wday;/* day-value range: [0, 6], where 0 indicates Sunday, 1 indicates Monday, and so on */
Int tm_yday;/* Number of days from January 1, 0,365 each year-value range: [1,]. 0 indicates January 1, and so on */
Int tm_isdst;/* identifier of the sequence. When the sequence is executed, the sequence is positive. When the sequence is not implemented, the tm_isdst value is 0. If the sequence is unknown, the tm_isdst () value is negative. */
};
2. Time operations
Clock: the number of clock units returned. Program Start running.
Time: returns the current time_t.
Difftime: calculate the time difference between time_t.
3. Conversion
Mktime: Convert TM structure to time_t
Asctime: Convert TM structure to string
Ctime: converts time_t to a string.
Gmtime: Convert time_t to TM as UTC time
Localtime: Convert time_t to TM as local time
Strftime: formatted as a string
Several Functions converted into strings: asctime, ctime, strftime
4. Macro
Clocks_per_sec: indicates the number of clock units in a second.

// Measurement event duration void test_clock_t () {long I = 1_l; clock_t start, finish; double duration; Start = clock (); /* measure the duration of an event */while (I --) {}; finish = clock (); duration = (double) (finish-Start)/clocks_per_sec; printf ("time to do 100000000 empty loops is % F seconds \ n", duration);} void test_time_t () {time_t t = time (null ); printf ("the calendar time now is % d \ n", T);} void test_difftime () {time_t start, end; Start = Time (null ); system ("pause"); End = Time (null); printf ("the pause used % 5.4f seconds. \ n ", difftime (end, start) ;}// the following are some Conversion Function applications // mktime: TM --> time_cvoid test_mktime () {struct tm t; time_t t_of_day; T. tm_year = 1997-1900; T. tm_mon = 6; T. tm_mday = 1; T. tm_hour = 0; T. tm_min = 0; T. tm_sec = 1; T. tm_wday = 4;/* day of the week */t. tm_yday = 0;/* does not show in asctime */t. tm_isdst = 0; t_of_day = mktime (& T); printf (ctime (& t_of_day);} // localtime: time_c --> tmvoid test_localtime () {time_t rawtime; struct TM * timeinfo; time (& rawtime); timeinfo = localtime (& rawtime); printf ("current local time and date: % s", asctime (timeinfo ));} // gmtime: time_c --> tmvoid test_gmtime () {time_t rawtime; struct TM * timeinfo; time (& rawtime); timeinfo = gmtime (& rawtime ); printf ("UTC time and date: % s", asctime (timeinfo);} // ctime: time_t --> stringvoid test_ctime () {time_t t = time (null ); STD: String STR = ctime (& T); STD: cout <STR <STD: Endl ;}