From: Martin Liesen <mliesen@netg.se>

Subject: RE: [delphi] Question regarding Dates

Date: Thu, 13 Jul 1995 00:43:20 +-200

As your question seams to be a general one, perhaps we should clear things

out once for all. This is what I have managed to find out about TDateTime

so far.

TDateTime is actually a floating point number defined like

TYPE TDateTime=float;

The definition goes something like this;

The real numer of the floating point matches the days passed since 1st Jan

the year of 0001. The fraction of the floationg point matches the time of

the day, where .0 would be midnight and .5 would be noon, 0.99999... would

be just befor midnight,

Using this representation of time& dates you can easliy calculate several

things,

Days beetwen dates:

days:=real(date1-date2);

Day of the week

dow:=date1 div 7;

Add 25 seconds to a date/time:

date:=date+25/(24*60*60);

There are several routines included in the SysUtils unit, giving you the

possibilty of converting & formating dates. Checkout the online manual.

A good startpoint is "TDateTime".

What you will have problem calculating is WeekNumber of date. If you would

like this function, I suspect that their is someone out there willing to

suply you with one, as it's a quite general & usefull code. Myself I use an

old routine I developed on BP7.0 using a quite simular techniqe as TDateTime.

I'll be happy to suply anyone with this library if requested.

If I were into dates below the year of 1700 I would first check out weather

Borland took in account that there were some ten missing dates, and this leap

was not introduced simultanious all across the world. My advice, check this

out if you're not going to sticking to the latest centuries.