On 8/27/2013 11:01 PM, Constantin Makshin wrote:
The original Calogero's message mentioned a file from December 2007, a
date outside of DST (unless there's a country that uses DST during
winter). Now it's August, so the DST is active and during "UTC -> local
time" conversion Windows adds that 1 hour Calogero is seeing. DST gets
incorrectly applied because it's active at the moment of conversion,
although it wasn't used at the moment the original timestamp represents.
I bet that the problem will go away when DST ends [again]. :)
I think Constantin's analysis is correct.
Just for your information, I'm using Qt 4.8.4. The machine where I
noticed the problem is running Microsoft Windows Server 2003.
The Time Zone is set to (GMT-05:00) Eastern Time (US & Canada), in DST
currently.
Let me know if you need any additional information
Calogero
On 08/27/2013 11:42 PM, Thiago Macieira wrote:
On terça-feira, 27 de agosto de 2013 22:59:44, Constantin Makshin wrote:
Windows can store information about daylight saving transitions for past
years, but always uses one for the current year. And since daylight
saving transition dates and time tend to slightly drift from year to
year, there's absolutely no guarantees of getting correct time
conversion results; in general case 1-hour error is nearly inevitable.
If you're on Windows, either calculate and apply DST yourself or forget
about correct "UTC <-> local time" conversions.
This is not about the corner case of a file that was created in the hour of the
transition, or even in the week that shifted between non-DST in one year to
DST in another (or vice-versa).
>From what I understand, we're talking about a file created in DST and checked
outside of DST (or vice-versa) in the *same* *year*.
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Calogero Mauceri
Software Engineer
Applied Coherent Technology Corporation (ACT)
www.actgate.com
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