procedure ClockToSec: convert &date to seconds procedure DateLineToSec: convert &dateline to seconds procedure DateToSec: convert &date to seconds procedure SecToClock: convert seconds to &clock procedure SecToDate: convert seconds to &date procedure SecToDateLine: convert seconds to &dateline procedure SecToUnixDate: convert seconds to UNIX time procedure IsLeapYear: determine if year is leap procedure calendat: Julian date procedure date: date in natural English procedure dayoweek: day of the week procedure full13th: full moons on Friday 13ths procedure julian: Julian date procedure pom: phase of moon procedure saytime: time in natural English procedure walltime: time since midnight
link datetime
August 9, 2000; Robert J. Alexander and Ralph E. Griswold
See also: datefns.icn
This file is in the public domain.
Notes:
- the default value for function parameters named
"hoursFromGmt" is the value of global variable
"HoursFromGmt" if nonnull, or environment variable
"HoursFromGmt" if set, or 0.
- The base year from which the "seconds" representation
of a date is calculated is by default 1970 (the ad hoc
standard used by both Unix and MS-Windows), but can be
changed by either setting the global variable
"DateBaseYear" or environment variable "DateBaseYear".
- There are some procedures not mentioned in this summary
that are useful: DateRecToSec(), SecToDateRec(). See the
source code for details.
ClockToSec(seconds)
converts a time in the format of &clock to seconds past
midnight.
DateLineToSec(dateline,hoursFromGmt)
converts a date in &dateline format to seconds since start of
dateBaseYear.
DateToSec(date,hoursFromGmt)
converts a date string in Icon &date format (yyyy/mm/dd)
to seconds past DateBaseYear.
SecToClock(seconds)
converts seconds past midnight to a string in the format of
&clock.
SecToDate(seconds,hoursFromGmt)
converts seconds past DateBaseYear to a string in Icon
&date format (yyyy/mm/dd).
SecToDateLine(seconds,hoursFromGmt)
produces a date in the same format as Icon's &dateline.
SecToUnixDate(seconds,hoursFromGmt)
returns a date and time in typical UNIX format:
Jan 14 10:24 1991.
IsLeapYear(year)
succeeds if year is a leap year, otherwise fails.
calendat(j)
returns a record with the month, day, and year corresponding
to the Julian Date Number j.
date() natural date in English.
dayoweek(day, month, year)
produces the day of the week for the given date.
Note carefully the parameter order.
full13th(year1, year2)
generates records giving the days on which a full moon occurs
on Friday the 13th in the range from year1 though year2.
julian(m, d, y)
returns the Julian Day Number for the specified
month, day, and year.
pom(n, phase)
returns record with the Julian Day number of fractional
part of the day for which the nth such phase since
January, 1900. Phases are encoded as:
0 - new moon
1 - first quarter
2 - full moon
3 - last quarter#
GMT is assumed.
saytime()
computes the time in natural English. If an argument is
supplied it is used as a test value to check the operation
the program.
walltime()
produces the number of seconds since midnight. Beware
wrap-around when used in programs that span midnight.
____________________________________________________________
Acknowledgement: Some of these procedures are based on an algorithm
given in "Numerical Recipes; The Art of Scientific Computing";
William H. Press, Brian P. Flannery, Saul A. Teukolsky, and William
T. Vetterling;# Cambridge University Press, 1986.