A Windows file time is a 64-bit value that represents the number of 100-nanosecond intervals that have elapsed since 12:00 midnight, January 1, 1601 A.D. (C.E.) Coordinated Universal Time (UTC). Windows uses a file time to record when an application creates, accesses, or writes to a file.

A Windows file time is directly accessible through the Windows API by calling the GetFileTime function, which returns a FILETIME structure. The single function parameter is the handle of the file whose file time information is to be retrieved. The file handle is retrieved by calling the CreateFile function. The FILETIME structure's dwHighDateTime member contains the four high-order bytes of the file time, and its dwLowDateTime member contains the four low-order bytes. The example that follows illustrates how to retrieve Windows file time values and convert them to DateTimeOffset values.

Windows file time values can also be created from DateTime values by calling the DateTime.ToFileTime and DateTime.ToFileTimeUtc methods, and from DateTimeOffset values by calling the DateTimeOffset.ToFileTime method.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 2.0.0.0, 4.0.0.0