Time Library

The Time Library contains functions and type definitions for time calculations in the UNIX time format which counts the number of seconds since the "epoch". This is very convenient for programs that work with time intervals: the difference between two UNIX time values is a real-time difference measured in seconds.

What is the epoch?
Originally it was defined as the beginning of 1970 GMT. ( January 1, 1970 Julian day ) GMT, Greenwich Mean Time, is a traditional term for the time zone in England.

The TimeStruct type is a structure type suitable for time and date storage.

Time_dateToEpoch

Prototype	function Time_dateToEpoch(var ts : TimeStruct) : longint;
Returns	Number of seconds since January 1, 1970 0h00mn00s.
Description	This function returns the UNIX time : number of seconds since January 1, 1970 0h00mn00s. Parameters : `ts:` time and date value for calculating UNIX time.
Requires	Nothing.
Example	var ts1 : TimeStruct; Epoch : longint; ... // what is the epoch of the date in ts ? epoch := Time_dateToEpoch(@ts1);

Time_epochToDate

Prototype	procedure Time_epochToDate(e: longint; var ts : TimeStruct);
Returns	Nothing.
Description	Converts the UNIX time to time and date. Parameters : `e:` UNIX time (seconds since UNIX epoch) `ts:` time and date structure for storing conversion output
Requires	Nothing.
Example	var ts2 : TimeStruct; epoch : longint; ... //what date is epoch 1234567890 ? epoch := 1234567890; Time_epochToDate(epoch,@ts2);

Time_dateDiff

Prototype	function Time_dateDiff(t1 : ^TimeStruct; t2 : ^TimeStruct) : longint;
Returns	Time difference in seconds as a signed long.
Description	This function compares two dates and returns time difference in seconds as a signed long. The result is positive if `t1` is before `t2`, null if `t1` is the same as `t2` and negative if `t1` is after `t2`. Parameters : `t1:` time and date structure (the first comparison parameter) `t2:` time and date structure (the second comparison parameter)
Requires	Nothing.
Example	var ts1, ts2 : TimeStruct; diff : longint; ... //how many seconds between these two dates contained in ts1 and ts2 buffers? diff := Time_dateDiff(@ts1, @ts2);

Library Example

Demonstration of Time library routines usage for time calculations in UNIX time format.

program Time_Demo;

program Time_Demo;

var epoch, diff : longint;

   ts1, ts2 : TimeStruct;

  begin
    ts1.ss := 0;
    ts1.mn := 7;
    ts1.hh := 17;
    ts1.md := 23;
    ts1.mo := 5;
    ts1.yy := 2006;

    {*
     * What is the epoch of the date in ts ?
     *}
    epoch := Time_dateToEpoch(ts1);


    {*
     * What date is epoch 1234567890 ?
     *}
    epoch := 1234567890;
    Time_epochToDate(epoch, ts2);

    {*
     * How much seconds between this two dates ?
     *}
    diff := Time_dateDiff(ts1, ts2);
  end.

TimeStruct type definition


type TimeStruct = record

        ss : byte;    // seconds
        mn : byte;    // minutes
        hh : byte;    // hours
        md : byte;    // day in month, from 1 to 31
        wd : byte;    // day in week, monday=0, tuesday=1, .... sunday=6
        mo : byte;    // month number, from 1 to 12 (and not from 0 to 11 as with unix C time !)
        yy : word;    // year Y2K compliant, from 1892 to 2038
        end;

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