Daylight Savings Time - time change on files


G

Guest

When windows xp changes to daylight savings time (which happened this
weekend) all the times on my files were changed (added 1 hour to them). Has
anybody got any idea how to correct this? I need to have the correct time on
files as I have a laptop (window xp) and desktop (windows 98) that have to be
sync.
 
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P

Pegasus \(MVP\)

Patricia Hunter said:
When windows xp changes to daylight savings time (which happened this
weekend) all the times on my files were changed (added 1 hour to them). Has
anybody got any idea how to correct this? I need to have the correct time on
files as I have a laptop (window xp) and desktop (windows 98) that have to be
sync.

This can happen when you change the time manually
instead of ticking the box in the Control Panel (Date and
Time, Time Zone tab) that instructs Windows to automatically
adjust the clock for daylight saving time changes. It could
also happen if you're in the wrong time zone.
 
G

Guest

Why does it matter what time zone you're in? Is there a difference between
London and New York when DST happens - isn't the computer reacting to the
date? I did click the box in the control panel in the time zone tab.
 
M

Mike Williams

Patricia said:
Why does it matter what time zone you're in? Is there a difference between
London and New York when DST happens - isn't the computer reacting to the
date? I did click the box in the control panel in the time zone tab.

Yes. Daylight savings happens at different times in different parts of
the world. It may line up occasionally, or two places may be out of sync
for a week or more.
 
P

Pegasus \(MVP\)

I deduct that you have a strong sense of humour:
You are contributing to a discussion about Daylight
Saving Time while fully aware that your own PC is
currently in an incorrect DST mode, thus posting
one hour in the future until this coming Sunday morning. :)
=====================
"David Candy" <.> wrote in message
Your time hasn't changed. Only the display has. If your programs are
correctly programmed they don't care what you see. On XP time is in GMT and
on 98 time is in local time. Programs have functions they can use to
compare.
 
D

David Candy

Your time hasn't changed. Only the display has. If your programs are correctly programmed they don't care what you see. On XP time is in GMT and on 98 time is in local time. Programs have functions they can use to compare.
 
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G

Guest

Thanks for all that !!!! I wasn't aware DST doesn't change until next week -
Ours changed on Sunday (London - British Summer Time). Is it possible to
change the display of the time on the files (reduce 1 hour) but not change
the computer time?
 
D

David Candy

That's correct. I'm not responsible for our state governments refusing to obey MS. Nor am I responsible for the Empire games (of which I saw NUFFIN of) which caused DST to be extended by a week. But the games ended on Sunday.

I was also the first to point out problems with Sydney 2000 DST dates. Which started in winter - that was wierd.

I could type timezone as I have resource kit installed. But I think dates shouldn't change.
 
D

David Candy

It only changed for this year only in Australia (and only southern Australia have daylight saving - northerners think cows can't tell the time). The times on the files haven't changed. How is it causing problems.

In Australia (east coast) we are UTC + 10 hours for standard time. UTC is the atomic equivilent of GMT which is calculated astronomically. They are both based on Greenwich (in London not Sydney).

Files are stored with GMT time. Explorer adds 10 hours to show me the time in winter and adds 11 hours to show me in summer. The file hasn't been touched.
 
D

David Candy

The answewr to your question is yes but what problems will this cause? What uses the time.
 
W

Wolf Kirchmeir

Patricia said:
When windows xp changes to daylight savings time (which happened this
weekend) all the times on my files were changed (added 1 hour to them). Has
anybody got any idea how to correct this? I need to have the correct time on
files as I have a laptop (window xp) and desktop (windows 98) that have to be
sync.


Good grief, really????

I just bought a laptop for my wife, with XP on it. I'm beginning to have
serious, and I mean serious, second thoughts. It's still not too late to
take it back...
 
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W

Wolf Kirchmeir

David said:
The answewr to your question is yes but what problems will this cause? What uses the time.


Backup programs may be set for time as well as date. Sync programs may
look at time as well as date.

BTW, we're still on standard time here.

Comment:

Wise old person of non-European descent, "What's with this Daylight
Saving Time, O wise person of European descent?"

"Oh, it gives us an extra hour of daylight."

"Huh. That's like cutting off the top of the blanket and sewing it on
the bottom."

"How so?"

"Blanket's still the same length."
 
G

Guest

The problem is: I have three different sources. My desktop (windows 98), my
laptop (xp) and a portable hard drive. They all have the same file
structure. When I back up my desktop on to my hard drive, I then plug the
hard drive into my laptop and do a comparison of files. All of the files on
the laptop (xp) previous to March 26 are going to be 1 hour later and in
order to be sure I have the latest file - will have to read them all.
 
G

Guest

Bascially open two windows (one for the hard drive on laptop and one for the
hard drive) and check files against each other - it is very tedious and time
consuming. Can you recommend a backup programme that compares file names and
checks for date and time?
 
D

David Candy

But a non faulty program can still do that. The time hasn't changed. She is only seeing what explorer interprets the time as.
There are five time formats. Time-related functions return time in one of these formats. You can also use the time functions to convert between time formats for ease of comparison and display. The following table summarizes the time formats.

Format Type Description
System SYSTEMTIME Year, month, day, hour, second, and millisecond, taken from the internal hardware clock.
File FILETIME 100-nanosecond intervals since January 1, 1601.
Local SYSTEMTIME or FILETIME A system time or file time converted to the system's local time zone.
MS-DOS WORD A packed word for the date, another for the time.
Windows DWORD The number of milliseconds since the system booted; a quantity that cycles every 49.7 days.

File Times and Daylight Saving Time
You must take care using file times if the user has set the system to automatically adjust for daylight saving time.

To convert a file time to local time, use the FileTimeToLocalFileTime function. However, FileTimeToLocalFileTime uses the current settings for the time zone and daylight saving time. Therefore, if it is daylight saving time, it will take daylight saving time into account, even if the file time you are converting is in standard time.

FAT records times on disk in local time. GetFileTime retrieves cached UTC times from FAT. When it becomes daylight saving time, the time retrieved by GetFileTime will be off an hour, because the cache has not been updated. When you restart the machine, the cached time retrieved by GetFileTime will be correct. FindFirstFile retrieves the local time from FAT and converts it to UTC using the current settings for the time zone and daylight saving time. Therefore, if it is daylight saving time, FindFirstFile will take daylight saving time into account, even if the file time you are converting is in standard time.

NTFS records times on disk in UTC. To account for daylight saving time when converting a file time to a local time, use the following functions instead of FileTimeToLocalFileTime:

1.. FileTimeToSystemTime
2.. SystemTimeToTzSpecificLocalTime
3.. SystemTimeToFileTime
 
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D

David Candy

Not really. I backup by remembering what is and isn't already backed up.

Change your clock while doing it. Why is this not simple and effective. Change time, do comparision, change time back.

Can xcopy handle it. Type xcopy in Help.

xcopy "c:\My Documents\" "\\laptop\my documents" /d /s /l /h /r

(/l makes it into a test of what would happen so you can see if it works without copying files)

MS has a thing called Synchtoy that sounds typically over engineered. I haven't seen it. It may suit you
http://www.microsoft.com/downloads/...54-c975-4814-9649-cce41af06eb7&DisplayLang=en
 
W

Wolf Kirchmeir

David said:
But a non faulty program can still do that. The time hasn't changed. She
is only seeing what explorer interprets the time as.
[snip page explaining stuff]

Thanks for that.
 
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