How to determine whether a date falls in Day Light Saving Time (DST)

smandeh · November 5th, 2009, 10:42 AM

I need to determine in XSLT 1.0 whether or not a date falls between Day Light Saving Time. For example: if the given date is 04/20/2008, I need to programmatically determine whether the date falls between the second sunday in March and the first Sunday in November.

DST_BEGIN: Second Sunday in March of every year
DST_END: First Sunday in November of every year

If I can get the DST_BEGIN date and DST_END date then I can do the comparison to determine whether or not a given date falls between DST time using these two dates.

Any help will be appreciated.

Thanks,
Scott

mhkay · November 5th, 2009, 10:59 AM

Obviously this can only be done if you know what country you are in (you seem to be giving US examples), and for dates in the past (national governments, or in some cases state governments, can change the clocks on a whim).

There are no standard faciities in XSLT 1.0 or 2.0 for this. You may be able to call extension functions in an external library. Saxon has an extension function saxon:in-summer-time() which would appear to meet your needs: see

http://www.saxonica.com/documentatio...mmer-time.html

It takes two arguments, the date/time in question, and an identifier for the civil time zone - either simply a country code, or an Olsen timezone name.

mhkay · November 5th, 2009, 11:04 AM

(Incidentally, you might be wondering why I called it in-summer-time() rather than in-daylight-savings-time(). One reason is that I'm British, and that's what we call it here. The main reason though is that daylight-savings is typical government-speak. They are telling us to get up an hour earlier in the morning, but they pretend that they are giving us more hours of sunshine in the day.)