July 9th, 2010

What's the difference between LastWriteTime and ChangeTime in FILE_BASIC_INFO?

Raymond Chen
Raymond Chen

The FILE_BASIC_INFO structure contains a number of fields which record the last time a particular action occurred. Two of the fields seem to describe the same thing.

Last­Write­Time
The time the file was last written to.

Change­Time

The time the file was changed.

What’s the difference between writing to a file and changing it? I’m told that the difference is metadata. The Last­Write­Time covers writes to the file’s data stream (which you accomplish via the Write­File function). On the other hand, the Change­Time also includes changes to the file metadata, such as changing its file attributes (hidden, read-only, etc.) or renaming the file.

(And don’t forget that Last­Access­Time updates are off by default now.)

Category
Old New Thing
Topics
Code

Author

Raymond Chen

Raymond has been involved in the evolution of Windows for more than 30 years. In 2003, he began a Web site known as The Old New Thing which has grown in popularity far beyond his wildest imagination, a development which still gives him the heebie-jeebies. The Web site spawned a book, coincidentally also titled The Old New Thing (Addison Wesley 2007). He occasionally appears on the Windows Dev Docs Twitter account to tell stories which convey no useful information.

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