January - Month of the date-errors

I learned something these days: date-functions are not only a good idea, you should also use them! Why? Because otherwise, you run into a whole lot of trouble, like scripts aborting without a reason, monthly log-data getting added to the wrong month, etc.

Take Perl for example. Paul Programmer does not want to reinvent the wheel and therefore uses Date::Calc for his date-related calculations. To get the number of days in a month he uses

$days = Days_in_Month($year,$month);

Nice, isn’t it? Unfortunately, the caffeine supply was temporarily suspended and so this code sprang into life to calculate last months number of days:

$days = Days_in_Month($year,$month-1);

Do you know what happened in January? Exactly, a run-time error. Bad! After the caffein supply was restored, Paul Programmer quickly fixed the bug with this:

my($lastyear,$lastmonth,$lastday) = Add_Delta_YM($year,$month, 1, 0, -1);
$days = Days_in_Month($lastyear,$lastmonth);

A lot nicer, isn’t it?

The same is true in Notes-Programming. If Nora Notesprogrammer wants to adjust a DateTime value, she uses the corresponding functions:

Dim dtToday As NotesDateTime
Dim dtLastMonth As NotesDateTime
Set dtToday = New NotesDateTime( "Today" )
Set dtlastMonth = dtToday
Call dtLastMonth.AdjustMonth( -1 )
Messagebox( "Today: " & dtToday.LocalTime )
Messagebox( "LastMonth: " & dtLastMonth.LocalTime )

Oh, and PLEASE do use functions/methods like „LocalTime” to get a string representation of the Date. Usually the give back the date formated (order of date and month, etc.) according to the local preferences.

Tagged as: , , , | Author:
[Freitag, 20070105, 20:51 | permanent link | 0 Kommentar(e)

Comments are closed for this story.


Disclaimer

„Leyrers Online Pamphlet“ ist die persönliche Website von mir, Martin Leyrer. Die hier veröffentlichten Beiträge spiegeln meine Ideen, Interessen, meinen Humor und fallweise auch mein Leben wider.
The postings on this site are my own and do not represent the positions, strategies or opinions of any former, current or future employer of mine.

Me, Elsewhere

Tag Cloud

2007, 2blog, 2do, 2read, a-trust, a.trust, a1, accessability, acta, advent, age, ai, amazon, ankündigung, apache, apple, audio, austria, backup, barcamp, basteln, bba, big brother awards, birthday, blog, blogging, book, books, browser, Browser_-_Firefox, bruce sterling, buch, bürgerkarte, cars, cartoon, ccc, cfp, christmas, cloud, coding, collection, command line, commandline, computer, computing, concert, conference, copyright, covid19, css, database, date, datenschutz, debian, delicious, demokratie, design, desktop, deutsch, deutschland, dev, developer, development, devops, digitalks, dilbert, disobay, dna, dns, Doctor Who, documentation, Domino, domino, Douglas Adams, download, downloads, drm, dsk, dvd, e-card, e-government, e-mail, e-voting, E71, education, Ein_Tag_im_Leben, elga, email, encryption, essen, EU, eu, event, events, exchange, Extensions, fail, fedora, feedback, film, firefox, flash, flightexpress, food, foto, fsfe, fun, future, games, gaming, geek, geld, git, gleichberechtigung, google, graz, grüne, grüninnen, hack, hacker, handtuch, handy, hardware, HHGTTG, history, how-to, howto, hp, html, humor, IBM, ibm, ical, iCalendar, image, innovation, intel, internet, internet explorer, iot, iphone, ipod, isp, it, IT, itfails, itfailsAT, itfailsDE, java, javascript, job, jobmarket, journalismus, keyboard, knowledge, konzert, language, laptop, law, lego, lenovo, life, links, Linux, linux, linuxwochen, linuxwochenende, live, living, lol, london, lost+found, Lotus, lotus, Lotus Notes, lotus notes, lotusnotes, LotusNotes, Lotusphere, lotusphere, Lotusphere2006, lotusphere2007, lotusphere2008, Lotusphere2008, lustig, m3_bei_der_Arbeit, mac, mail, marketing, mathematik, media, medien, metalab, Microsoft, microsoft, mITtendrin, mobile, mood, motivation, movie, mp3, multimedia, music, musik, männer, nasa, nerd, netwatcher, network, netzpolitik, news, nokia, notes, Notes, Notes+Domino, office, online, OOXML, open source, openoffice, opensource, orf, orlando, os, outlook, patents, pc, pdf, performance, perl, personal, php, picture, pictures, podcast, politics, politik, pr, press, presse, privacy, privatsphäre, productivity, programming, protest, public speaking, qtalk, quintessenz, quote, quotes, radio, rant, recherche, recht, release, review, rezension, rip, rss, science, search, security, server, settings, sf, shaarli, Show-n-tell thursday, sicherheit, silverlight, smtp, SnTT, social media, software, sony, sound, space, spam, sprache, spö, ssh, ssl, standards, storage, story, stupid, summerspecial, sun, surveillance, sysadmin, talk, talks, technology, The Hitchhikers Guide to the Galaxy, theme, think, thinkpad, thunderbird, tip, tipp, tools, topgear, torrent, towel, Towel Day, TowelDay, travel, truth, tv, twitter, ubuntu, ui, uk, unix, update, usa, usb, vds, video, videoüberwachung, vienna, vim, Vim, vintage, vista, vorratsdatenspeicherung, vortrag, wahl, wcm, web, web 2.0, web2.0, web20, Web20, webdesign, werbung, wien, wiener linien, wikileaks, windows, windows 7, wired, wishlist, wissen, Wissen_ist_Macht, wlan, work, workshops, wow, writing, wtf, Wunschzettel, wunschzettel, www, xbox, xml, xp, zensur, zukunft, zune, österreich, övp, übersetzung, überwachung

AFK Readinglist