localtime, localtime64 - Date and current time as a structure

Definition	#include <time.h> struct tm *localtime(const time_t *sec_p); struct tm *localtime64(const time64_t *sec_p); localtime and localtime64 interpret the time specification to which sec_p points as the number of seconds which have passed since the reference date (epoch). The functions calculate the date and time from this and store the result in a structure of the type tm. Negative values are interpreted as seconds before the reference date. The earliest displayable date with localtime is 12/13/1901 20:45:52 local time and 01/01/1900 00:00:00 with localtime64. The latest date which can be displayed with localtime is 01/19/2038 03:14:07 and 3/18/4317 02:44:48 with localtime64.
Return val.	Pointer to the calculated structure. localtime and localtime64 store the result in a structure declared in <time.h> as follows:
		struct tm { int tm_sec; /* seconds (0-59) */ int tm_min; /* minutes (0-59) */ int tm_hour; /* hours (0-23) */ int tm_mday; /* day of the month (1-31) */ int tm_mon; /* month from the start of the year (0-11) */ int tm_year; /* years since 1900 */ int tm_wday; /* weekday (0-6, Sunday=0) */ int tm_yday; /* days since January 1 (0-365) */ int tm_isdst; /* daylight saving time flag */ };
	NULL	In the event of an error
Notes	The asctime, ctime, ctime64, gmtime, gmtime64, localtime and localtime64 functions write their result into the same internal C data area. This means that each of these function calls overwrites the previous result of any of the other functions. localtime and localtime64 map all dates before 1/1/1900 01:00:00 to 1/1/1900 01:00:00.
Example	#include <time.h> #include <stdio.h> struct tm *t; time_t clk; char *s; int main(void) { clk = time((time_t *)0); t = localtime(&clk);  printf("Year: %d\n", t->tm_year + 1900);   printf("Time in hours: %d\n", t->tm_hour);  printf("Day of the year: %d\n", t->tm_yday);  s = asctime(t);  printf("%s", s); return 0; }