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Hi Mike, I believe it's fair to say that your formula does have a base date -- the base is simply the year zero, or somewhere thereabouts. At least one of the methods mentioned handles dates prior to the base date by checking for negatives. IBM's date routines don't allow us to specify dates prior to 01/01/0001, but as someone mentioned, that's sufficient for most business purposes. Museums trying to keep track of artifacts, or historians trying to create a database with a timeline might want a much longer view. What's the day of week for April 5, 1500BC? Regards, Peter Dow Dow Software Services, Inc. 909 425-0194 voice 909 425-0196 fax ----- Original Message ----- From: "Wills, Mike N. (TC)" <MNWills@taylorcorp.com> To: <RPG400-L@midrange.com> Sent: Wednesday, May 16, 2001 7:41 AM Subject: RE: Can I get the Day of the week? > There is a mathematical formula for getting the day of the week: > > D = Day > M = Month > Y = the last two digits of the year > C = Century > > ((d + y) - (2 * c) + (y / 4) + (c / 4) + ((13 * m - 1) / 5)) % 7 = Day > > For the Day: 0 = Sunday, 1 = Monday, etc. > For some reason my program is a day off right now but I am positive I had it > working before. I haven't taken the time to debug it yet. This was done in > C++ on a PC. I need to double check my formula. > > But with this formula it doesn't depend on a known date. I don't know if it > could cause problems, I just remember people keep on saying to NOT hard-code > anything in if possible (although I am sure many of us do anyway). This is a > formula that my instructor gave me and I have seen it on the web. Then, if > you (for some weird reason) need a day from the 1600's you can get it. > > -----Original Message----- > From: DeLong, Eric [mailto:EDeLong@Sallybeauty.com] > Sent: Wednesday, May 16, 2001 8:51 AM > To: 'RPG400-L@midrange.com' > Subject: RE: Can I get the Day of the week? > > > No. I can't see that that's a problem. Personally, I can't see how one could > determine the DOW without some sort of known date. These DOW functions are > both simple and effective. What's the problem? > > Eric DeLong > > -----Original Message----- > From: Wills, Mike N. (TC) [mailto:MNWills@taylorcorp.com] > Sent: Wednesday, May 16, 2001 8:30 AM > To: 'RPG400-L@midrange.com' > Subject: RE: Can I get the Day of the week? > > > The one problem I have with most of these suggestions is that the date is > then dependant upon a known date. Doesn't other people see something wrong > with this? > > Mike > > -----Original Message----- > From: boldt@ca.ibm.com [mailto:boldt@ca.ibm.com] > Sent: Wednesday, May 16, 2001 7:12 AM > To: rpg400-l@midrange.com > Subject: Re: Can I get the Day of the week? > > > From: "Christopher J. Devous" <cdevous@antigua.com> > Subject: RE: Can I get the Day of the week? > Christopher wrote: > >Try this, it's based on the famous "Doomsday" algorithm by JH Conway: > > > > 100 > ************************************************************************** > > 200 *** > > 300 *** Program Name -- DOWK > > 400 *** Description -- Calculate Day of Week from > Gregorian > > 500 *** Date > > 600 *** Author -- Christopher J. Devous > > As much as I respect John Horton Conway, RPG programmers can't do > day of week computation much shorter than with this procedure: > > //\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\// > // Procedure: DayOfWeek // > // Purpose: Determine the day of week for a particular date // > // Parameters: // > // I: dt -- date // > // Returns: // > // 0..6 -- 0=Sunday, 1=Monday, 2=Tuesday, etc. // > // Notes: // > // January 5, 1800 is a Sunday. This procedure only works for // > // dates later than 1800-01-05. // > //\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\// > P DayOfWeek b > D DayOfWeek pi 10i 0 > D dt d value datfmt(*iso) > /free > return %rem (%diff (dt: d'1800-01-05': *days): 7); > /end-free > P DayOfWeek e > > > > > > Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com > > +--- > | This is the RPG/400 Mailing List! > | To submit a new message, send your mail to RPG400-L@midrange.com. > | To subscribe to this list send email to RPG400-L-SUB@midrange.com. > | To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com. > | Questions should be directed to the list owner/operator: > david@midrange.com > +--- > +--- > | This is the RPG/400 Mailing List! > | To submit a new message, send your mail to RPG400-L@midrange.com. > | To subscribe to this list send email to RPG400-L-SUB@midrange.com. > | To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com. > | Questions should be directed to the list owner/operator: > david@midrange.com > +--- > > +--- > | This is the RPG/400 Mailing List! > | To submit a new message, send your mail to RPG400-L@midrange.com. > | To subscribe to this list send email to RPG400-L-SUB@midrange.com. > | To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com. > | Questions should be directed to the list owner/operator: > david@midrange.com > +--- > +--- > | This is the RPG/400 Mailing List! > | To submit a new message, send your mail to RPG400-L@midrange.com. > | To subscribe to this list send email to RPG400-L-SUB@midrange.com. > | To unsubscribe from this list send email to RPG400-L-UNSUB@midrange.com. > | Questions should be directed to the list owner/operator: david@midrange.com > +--- _________________________________________________________ Do You Yahoo!? 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