DateTime

Date and Time module.

Adapted from Julia. License is MIT: https://julialang.org/license

A Date value is encoded as an LONGLONGINT, counting milliseconds from an epoch. The epoch is 0000-12-31T00:00:00.

Days are adjusted accoring to Rata Die approch to simplify date calculations.

Const

ERROR* = -1;

Types

DATETIME* = LONGLONGINT;

TType* = (Year, Quarter, Month, Week, Day, Weekday, Hour, Min, Sec, MSec);

Procedures

TryEncodeDate

Return TRUE if the year, month & day is successful converted to a valid DATETIME

PROCEDURE TryEncodeDate* (VAR date : DATETIME; year,month,day : LONGINT) : BOOLEAN;

EncodeDate

Return Encoded date. Return ERROR if not valid

PROCEDURE EncodeDate* (year, month, day : LONGINT): DATETIME;

TryEncodeDateTime

Return TRUE if Year, Month, Day, Hour, Min, Sec & MSec is successful converted to a valid DATETIME

PROCEDURE TryEncodeDateTime* (VAR datetime : DATETIME; year, month, day, hour, min, sec, msec : LONGINT) : BOOLEAN;

EncodeDateTime

Return encoded DATETIME. Return ERROR if not valid

PROCEDURE EncodeDateTime* (year, month, day, hour, min, sec : LONGINT; msec := 0 : LONGINT): DATETIME;

DecodeDate

Decode DATETIME to Year, Month & Day

PROCEDURE DecodeDate* (datetime: DATETIME; VAR year, month, day: LONGINT);

DecodeTime

Decode DATETIME to Hour, Min, Sec & MSec

PROCEDURE DecodeTime* (datetime: DATETIME; VAR hour, min, sec, msec: LONGINT);

DecodeDateTime

Decode DATETIME to Year, Month, Day, Hour, Min, Sec & MSec

PROCEDURE DecodeDateTime* (VAR year, month, day, hour, min, sec, msec: LONGINT; datetime: DATETIME);

DateTimeToDate

Remove time part of DATETIME

PROCEDURE DateTimeToDate* (datetime: DATETIME) : DATETIME;

Now

Current DATETIME

PROCEDURE Now* (): DATETIME;

Today

Current Date

PROCEDURE Today* (): DATETIME;

IncYear

Increment Year of DATETIME and return modified value

PROCEDURE IncYear* (datetime: DATETIME; years : LONGINT) : DATETIME;

DecYear

Decrement Year of DATETIME and return modified value

PROCEDURE DecYear* (datetime: DATETIME; years : LONGINT) : DATETIME;

IncMonth

Increment Month of DATETIME and return modified value

PROCEDURE IncMonth* (datetime: DATETIME; months : LONGINT) : DATETIME;

DecMonth

Deccrement Month of DATETIME and return modified value

PROCEDURE DecMonth*(datetime: DATETIME; months : LONGINT) : DATETIME;

Inc

Increment DATETIME with Value according to Type.

PROCEDURE Inc* (VAR datetime : DATETIME; typ : TType; value : LONGLONGINT);

Dec

Decrement DATETIME with Value according to Type.

PROCEDURE Dec* (VAR datetime : DATETIME; typ : TType; value : LONGLONGINT);

Extract

Extract component of DATETIME

PROCEDURE Extract* (datetime : DATETIME; typ : TType) : LONGINT;

Trunc

Trucate DATETIME value according to Type. Usefull for comparison, calculate spans or finding start of periods (week, month).

PROCEDURE Trunc* (datetime : DATETIME; typ : TType) : DATETIME;

Diff

Compute difference between two dates. Extract year, month, day to get difference

PROCEDURE Diff* (dtstart, dtend: DATETIME; addEndDay := FALSE : BOOLEAN) : DATETIME;

Span

Calculate DATETIME span between Start and End according to Type

PROCEDURE Span* (dtstart, dtend: DATETIME; typ : TType) : LONGINT;

FromString

Try to parse string to a DATETIME according to format string:

  • %y : Year with century : 0 - 9999

  • %m : Month : 1 - 12

  • %d : Day of the month : 1 - XX

  • %H : Hour (24-hour clock) : 0 - 23

  • %M : Minute : 0 - 59

  • %S : Second : 0 - 59

  • %f : Milliseconds : 0 - 999

  • %t : One or more TAB or SPC characters

  • %% : Literal % char

Numbers can be zero padded. Other characters must match exactly.

Return -1 on failure or number of characters converted.

PROCEDURE FromString* (VAR datetime : DATETIME; src- : ARRAY OF CHAR; fmt- : ARRAY OF CHAR; start := 0 : LONGINT): LONGINT;