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.

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[Freitag, 20070105, 21:51 | permanent link | 0 Kommentar(e)

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„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.
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