Summer & Winter time
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How do I check whether it's summertime or wintertime for a given date x? How do I determine when switches between summertime and wintertime occur?
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How do I check whether it's summertime or wintertime for a given date x? How do I determine when switches between summertime and wintertime occur?
Well I still don't know how to easily check exactly when a switch between winter and summer time would occur, but I did figure out how to determine which one of the 2 is in effect at any given date x. The Daylight Savings Time flag indicates whether the current time for your locale is summertime (1) or wintertime (0), example:
time_t t1; // Get current time (our given date x) time(&t1); // Adjust for locale struct tm * t2 = localtime(&t1); printf("DST Now:%d\n", t2->tm_isdst); // Substract 90 days t1 -= 7776000; // Adjust for locale t2 = localtime(&t1); printf("DST Then:%d\n", t2->tm_isdst);Still trying to find out exactly when shifts occur though. -
How do I check whether it's summertime or wintertime for a given date x? How do I determine when switches between summertime and wintertime occur?
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How do I check whether it's summertime or wintertime for a given date x? How do I determine when switches between summertime and wintertime occur?
Look up GetTimeZoneInformation(), it fills a TIME_ZONE_INFORMATION structure where you can get the SYSTEMTIME of the daylight date and the standard date. [edit]:doh: forgot to tell you that the return value actually tells you if it is daylight saving time or not.[/edit] "After all it's just text at the end of the day. - Colin Davies "For example, when a VB programmer comes to my house, they may say 'does your pool need cleaning, sir ?' " - Christian Graus
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The switch from summer to winter happens on the last Sunday of October at 2:am I think. The switch from winter to summer on the last Sunday of March again at 2am Hope this helps you.. Greets, Davy
Anonymous wrote: The switch from summer to winter happens on the last Sunday of October at 2:am I think. The switch from winter to summer on the last Sunday of March again at 2am :-D Could be that a more i18n safe procedure is called for. "After all it's just text at the end of the day. - Colin Davies "For example, when a VB programmer comes to my house, they may say 'does your pool need cleaning, sir ?' " - Christian Graus
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How do I check whether it's summertime or wintertime for a given date x? How do I determine when switches between summertime and wintertime occur?
For this you'll need to read up on the winter and summer solstice: http://scienceworld.wolfram.com/astronomy/WinterSolstice.html http://scienceworld.wolfram.com/astronomy/SummerSolstice.html
"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
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The switch from summer to winter happens on the last Sunday of October at 2:am I think. The switch from winter to summer on the last Sunday of March again at 2am Hope this helps you.. Greets, Davy
Only in the parts of the US that bother with the stupid thing. Several US states (or parts of states in at least one case) do not bother with it at all. Many countries around the world have their own date, which is not the same as the US date. Better look for a different way to figure it out. Best is to get everyone off the stupid idea. I have yet to hear a good argument for daylight savings time. Thats a different rant though, so I'll head over to soapbox someday and give it to those interested.
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How do I check whether it's summertime or wintertime for a given date x? How do I determine when switches between summertime and wintertime occur?
If you actually mean what the season is, not just the daylight saving time flag, there isn't a single algorithm for it since different countries define the seasons differently. Ie if you try to tell someone in Australia that December 25 is in the winter, you'll get weird looks. Also, some countries like the US define the seasons based on the solstices and equinoxes, while others change seasons on the first of the month every 3 months. --Mike-- LINKS~! Ericahist | 1ClickPicGrabber | CP SearchBar v2.0.2 | C++ Forum FAQ | You Are Dumb