Different timestamps under winXP, win7 and vb.net

Question

Within a VB.net program I used IO.File.GetCreationTime to read the file system's creation time of a file. I was irritated, because the returned value didn't match with the time displayed in the explorer. On another machine the time was displayed correctly.

• Both machines use NTFS
• I copied the file from a read-only FAT32 USB-drive to the desktop of each machine
• Both machines are using the same time zone (GMT+1 plus DST)

timestamps displayed:

• my VB.net app (both machines) - 21:09
• Explorer time Windows XP - 22:09
• Explorer time Windows 7 - 21:09
• (MacOS X - 21:09)

The good thing is, that the file I'm talking about is a PDF file. According to the PDF's meta information the file was created on 03. Jan. 2002 22:09

I want that the file system dates are the same on every machine. How would you solve this problem using VB.net?

Answer 1

I used a simple app to summarize the timestamp information:

GetLastWriteTime(file)
GetLastWriteTimeUtc(file)
GetLastWriteTime(file).ToLocalTime
GetLastWriteTimeUtc(file).ToLocalTime
GetLastWriteTime(file).ToFileTime
GetLastWriteTimeUtc(file).ToFileTime

Date.Now
Date.Now.UtcNow

The output was the same on both machines. For some reason I changed the time zone settings on both machines, switching DST on and off. The result is interesting ...

• ... when you turn off DST on Windows XP all time stamps are reduced by one (because during DST my time zone is GMT+2 (now) , during the wintertime it is GMT+1)
• ... on a Windows 7 machine only files created during DST (GMT+2) are affected by this (my file was created in January)

I guess it's the same effect vice versa. So my problem is just a disply issue. To solve this I will only use the UTC-Functions and care about DST within my app. So there still will be an offset, but it should be ok as long as it is just a display issue.