mdw@git.distorted.org.uk Git - ezmlm/blob - datetime.3

   1 .TH datetime 3
   2 .SH NAME
   3 datetime \- convert between TAI labels and seconds
   4 .SH SYNTAX
   5 .B #include <datetime.h>
   6
   7 void \fBdatetime_tai\fP(&\fIdt\fR,\fIt\fR);
   8
   9 datetime_sec \fBdatetime_untai\fP(&\fIdt\fR);
  10
  11 struct datetime \fIdt\fR;
  12 .br
  13 datetime_sec \fIt\fR;
  14 .SH DESCRIPTION
  15 International Atomic Time, TAI,
  16 is the fundamental unit for time measurements.
  17 TAI has one label for every second of real time,
  18 without complications such as leap seconds.
  19
  20 A
  21 struct datetime
  22 variable,
  23 such as
  24 .IR dt ,
  25 stores a TAI label.
  26 .I dt\fB.year
  27 is the year number minus 1900;
  28 .I dt\fB.mon
  29 is the month number, from 0 (January) through 11 (December);
  30 .I dt\fB.mday
  31 is the day of the month, from 1 through 31;
  32 .I dt\fB.hour
  33 is the hour, from 0 through 23;
  34 .I dt\fB.min
  35 is the minute, from 0 through 59;
  36 .I dt\fB.sec
  37 is the second, from 0 through 59;
  38 .I dt\fB.wday
  39 is the day of the week, from 0 (Sunday) through 6 (Saturday);
  40 .I dt\fB.yday
  41 is the day of the year, from 0 through 365.
  42
  43 The
  44 .B datetime
  45 library supports more convenient TAI manipulation with
  46 the datetime_sec type.
  47 A datetime_sec value, such as
  48 .IR t ,
  49 is an integer referring to the
  50 .IR t th
  51 second after the beginning of 1970 TAI.
  52 The first second of 1970 TAI was 0;
  53 the next second was 1;
  54 the last second of 1969 TAI was -1.
  55 The difference between two datetime_sec values is a number
  56 of real-time seconds.
  57
  58 .B datetime_tai
  59 converts a datetime_sec to a TAI label.
  60
  61 .B datetime_untai
  62 reads a TAI label
  63 (specifically
  64 .IR dt\fB.year ,
  65 .IR dt\fB.mon ,
  66 .IR dt\fB.mday ,
  67 .IR dt\fB.hour ,
  68 .IR dt\fB.min ,
  69 and
  70 .IR dt\fB.sec )
  71 and returns a datetime_sec.
  72 .SH "SEE ALSO"
  73 now(3)