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.. index:: single: datep .. _datep/0:
.. rst-class:: right
protocol
datep
Date protocol.
| Availability:
| logtalk_load(dates(loader))
| Author: Paulo Moura | Version: 1:2:0 | Date: 2026-02-25
| Compilation flags:
| static
| Dependencies: | (none)
| Remarks: | (none)
| Inherited public predicates: | (none)
.. contents:: :local: :backlinks: top
Public predicates
.. index:: today/3 .. _datep/0::today/3:
today/3 ^^^^^^^^^^^
Returns current date.
| Compilation flags:
| static
| Template:
| today(Year,Month,Day)
| Mode and number of proofs:
| today(-integer,-integer,-integer) - one
.. index:: leap_year/1 .. _datep/0::leap_year/1:
leap_year/1 ^^^^^^^^^^^^^^^
True if the argument is a leap year.
| Compilation flags:
| static
| Template:
| leap_year(Year)
| Mode and number of proofs:
| leap_year(+integer) - zero_or_one
.. index:: name_of_day/3 .. _datep/0::name_of_day/3:
name_of_day/3 ^^^^^^^^^^^^^^^^^
Name and short name of day.
| Compilation flags:
| static
| Template:
| name_of_day(Index,Name,Short)
| Mode and number of proofs:
| name_of_day(?integer,?atom,?atom) - zero_or_more
.. index:: name_of_month/3 .. _datep/0::name_of_month/3:
name_of_month/3 ^^^^^^^^^^^^^^^^^^^
Name and short name of month.
| Compilation flags:
| static
| Template:
| name_of_month(Index,Name,Short)
| Mode and number of proofs:
| name_of_month(?integer,?atom,?atom) - zero_or_more
.. index:: days_in_month/3 .. _datep/0::days_in_month/3:
days_in_month/3 ^^^^^^^^^^^^^^^^^^^
Number of days in a month.
| Compilation flags:
| static
| Template:
| days_in_month(Month,Year,Days)
| Mode and number of proofs:
| days_in_month(?integer,+integer,?integer) - zero_or_more
.. index:: valid/3 .. _datep/0::valid/3:
valid/3 ^^^^^^^^^^^
True if the arguments represent a valid date.
| Compilation flags:
| static
| Template:
| valid(Year,Month,Day)
| Mode and number of proofs:
| valid(@integer,@integer,@integer) - zero_or_one
.. index:: date_time_to_unix/2 .. _datep/0::date_time_to_unix/2:
date_time_to_unix/2 ^^^^^^^^^^^^^^^^^^^^^^^
Converts a UTC date-time term date_time(Year,Month,Day,Hours,Minutes,Seconds) to Unix epoch seconds.
| Compilation flags:
| static
| Template:
| date_time_to_unix(DateTime,UnixTime)
| Mode and number of proofs:
| date_time_to_unix(+compound,-integer) - zero_or_one
.. index:: unix_to_date_time/2 .. _datep/0::unix_to_date_time/2:
unix_to_date_time/2 ^^^^^^^^^^^^^^^^^^^^^^^
Converts Unix epoch seconds to a UTC date-time term date_time(Year,Month,Day,Hours,Minutes,Seconds).
| Compilation flags:
| static
| Template:
| unix_to_date_time(UnixTime,DateTime)
| Mode and number of proofs:
| unix_to_date_time(+integer,-compound) - one
.. index:: add_duration/3 .. _datep/0::add_duration/3:
add_duration/3 ^^^^^^^^^^^^^^^^^^
Adds a duration to a datetime. Duration can be integer seconds or duration(Days,Hours,Minutes,Seconds).
| Compilation flags:
| static
| Template:
| add_duration(DateTime,Duration,ResultDateTime)
| Mode and number of proofs:
| add_duration(+compound,+nonvar,-compound) - zero_or_one
.. index:: subtract_duration/3 .. _datep/0::subtract_duration/3:
subtract_duration/3 ^^^^^^^^^^^^^^^^^^^^^^^
Subtracts a duration from a datetime. Duration can be integer seconds or duration(Days,Hours,Minutes,Seconds).
| Compilation flags:
| static
| Template:
| subtract_duration(DateTime,Duration,ResultDateTime)
| Mode and number of proofs:
| subtract_duration(+compound,+nonvar,-compound) - zero_or_one
.. index:: duration_between/3 .. _datep/0::duration_between/3:
duration_between/3 ^^^^^^^^^^^^^^^^^^^^^^
Computes the difference between two datetimes as integer seconds or as duration(Days,Hours,Minutes,Seconds).
| Compilation flags:
| static
| Template:
| duration_between(StartDateTime,EndDateTime,Duration)
| Mode and number of proofs:
| duration_between(+compound,+compound,?term) - zero_or_one
.. index:: utc_to_local/3 .. _datep/0::utc_to_local/3:
utc_to_local/3 ^^^^^^^^^^^^^^^^^^
Converts a UTC datetime to a local datetime using an explicit timezone offset atom (Z or ±HH:MM).
| Compilation flags:
| static
| Template:
| utc_to_local(UTCDateTime,Offset,LocalDateTime)
| Mode and number of proofs:
| utc_to_local(+compound,+atom,-compound) - zero_or_one
.. index:: local_to_utc/3 .. _datep/0::local_to_utc/3:
local_to_utc/3 ^^^^^^^^^^^^^^^^^^
Converts a local datetime to UTC using an explicit timezone offset atom (Z or ±HH:MM).
| Compilation flags:
| static
| Template:
| local_to_utc(LocalDateTime,Offset,UTCDateTime)
| Mode and number of proofs:
| local_to_utc(+compound,+atom,-compound) - zero_or_one
.. index:: day_of_year/2 .. _datep/0::day_of_year/2:
day_of_year/2 ^^^^^^^^^^^^^^^^^
Computes the day of year (1-366) for a date(Year,Month,Day) or date_time(...) term.
| Compilation flags:
| static
| Template:
| day_of_year(DateLike,DayOfYear)
| Mode and number of proofs:
| day_of_year(+compound,?integer) - zero_or_one
.. index:: week_of_year_iso/2 .. _datep/0::week_of_year_iso/2:
week_of_year_iso/2 ^^^^^^^^^^^^^^^^^^^^^^
Computes ISO week for a date(Year,Month,Day) or date_time(...) term as week(Week,Year).
| Compilation flags:
| static
| Template:
| week_of_year_iso(DateLike,ISOWeek)
| Mode and number of proofs:
| week_of_year_iso(+compound,?compound) - zero_or_one
.. index:: weekday/2 .. _datep/0::weekday/2:
weekday/2 ^^^^^^^^^^^^^
Computes ISO weekday number (Monday=1, ..., Sunday=7) for a date(Year,Month,Day) or date_time(...) term.
| Compilation flags:
| static
| Template:
| weekday(DateLike,Weekday)
| Mode and number of proofs:
| weekday(+compound,?integer) - zero_or_one
.. index:: normalize_date_time/2 .. _datep/0::normalize_date_time/2:
normalize_date_time/2 ^^^^^^^^^^^^^^^^^^^^^^^^^
Normalizes a datetime term by carrying overflows/underflows in date and time fields.
| Compilation flags:
| static
| Template:
| normalize_date_time(DateTime,NormalizedDateTime)
| Mode and number of proofs:
| normalize_date_time(+compound,-compound) - one
.. index:: valid_date_time/1 .. _datep/0::valid_date_time/1:
valid_date_time/1 ^^^^^^^^^^^^^^^^^^^^^
True iff a datetime term is valid in strict mode.
| Compilation flags:
| static
| Template:
| valid_date_time(DateTime)
| Mode and number of proofs:
| valid_date_time(@compound) - zero_or_one
.. index:: valid_date_time/2 .. _datep/0::valid_date_time/2:
valid_date_time/2 ^^^^^^^^^^^^^^^^^^^^^
Validates a datetime term in strict or relaxed mode.
| Compilation flags:
| static
| Template:
| valid_date_time(DateTime,Mode)
| Mode and number of proofs:
| valid_date_time(@compound,+atom) - zero_or_one
Protected predicates
(none)
Private predicates
(none)
Operators
(none)
.. seealso::