C converts the time to the filename usage method

The return value
Type: System Int64
The value of the current DateTime object represented as the time of the Windows file.

Such as:

DateTime.Now.ToFileTime().ToString()

You get a string like 130308237880937500

The Windows file time is a 64-bit value that represents the number of intervals (one interval in 100 nanoseconds) that have passed since 12:00 midnight coordinated universal time (UTC) AD (C.E.) on January 1, 1601. Windows USES file time to record when an application creates, accesses, or writes files.

Previous versions of the ToFileTime method assumed that the current DateTime object was local time. Starting with.NET Framework 2.0, the ToFileTime method USES the Kind property to determine whether the current DateTime object is a local time, an UTC time, or an unspecified type of time that is considered a local time.