datetime(3) [debian man page]
datetime(3) Library Functions Manual datetime(3) NAME
datetime - convert between TAI labels and seconds SYNTAX
#include <datetime.h> void datetime_tai(&dt,t); datetime_sec datetime_untai(&dt); struct datetime dt; datetime_sec t; DESCRIPTION
International Atomic Time, TAI, is the fundamental unit for time measurements. TAI has one label for every second of real time, without complications such as leap seconds. A struct datetime variable, such as dt, stores a TAI label. dt.year is the year number minus 1900; dt.mon is the month number, from 0 (January) through 11 (December); dt.mday is the day of the month, from 1 through 31; dt.hour is the hour, from 0 through 23; dt.min is the minute, from 0 through 59; dt.sec is the second, from 0 through 59; dt.wday is the day of the week, from 0 (Sunday) through 6 (Saturday); dt.yday is the day of the year, from 0 through 365. The datetime library supports more convenient TAI manipulation with the datetime_sec type. A datetime_sec value, such as t, is an integer referring to the tth second after the beginning of 1970 TAI. The first second of 1970 TAI was 0; the next second was 1; the last second of 1969 TAI was -1. The difference between two datetime_sec values is a number of real-time seconds. datetime_tai converts a datetime_sec to a TAI label. datetime_untai reads a TAI label (specifically dt.year, dt.mon, dt.mday, dt.hour, dt.min, and dt.sec) and returns a datetime_sec. SEE ALSO
now(3) datetime(3)
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CTIME(2) System Calls Manual CTIME(2) NAME
ctime, localtime, gmtime, asctime, timezone - convert date and time to ASCII SYNOPSIS
#include <u.h> #include <libc.h> char* ctime(long clock) Tm* localtime(long clock) Tm* gmtime(long clock) char* asctime(Tm *tm) /env/timezone DESCRIPTION
Ctime converts a time clock such as returned by time(2) into ASCII (sic) and returns a pointer to a 30-byte string in the following form. All the fields have constant width. Wed Aug 5 01:07:47 EST 1973 Localtime and gmtime return pointers to structures containing the broken-down time. Localtime corrects for the time zone and possible day- light savings time; gmtime converts directly to GMT. Asctime converts a broken-down time to ASCII and returns a pointer to a 30-byte string. typedef struct { int sec; /* seconds (range 0..59) */ int min; /* minutes (0..59) */ int hour; /* hours (0..23) */ int mday; /* day of the month (1..31) */ int mon; /* month of the year (0..11) */ int year; /* year A.D. - 1900 */ int wday; /* day of week (0..6, Sunday = 0) */ int yday; /* day of year (0..365) */ char zone[4]; /* time zone name */ } Tm; When local time is first requested, the program consults the timezone environment variable to determine the time zone and converts accord- ingly. (This variable is set at system boot time by init(8).) The timezone variable contains the normal time zone name and its difference from GMT in seconds followed by an alternate (daylight) time zone name and its difference followed by a newline. The remainder is a list of pairs of times (seconds past the start of 1970, in the first time zone) when the alternate time zone applies. For example: EST -18000 EDT -14400 9943200 25664400 41392800 57718800 ... Greenwich Mean Time is represented by GMT 0 SOURCE
/sys/src/libc/9sys SEE ALSO
date(1), time(2), init(8) BUGS
The return values point to static data whose content is overwritten by each call. Daylight Savings Time is ``normal'' in the Southern hemisphere. These routines are not equipped to handle non-ASCII text, and are provincial anyway. CTIME(2)