About Time

Time-related functions return time in one of several formats. You can use the time functions to convert between some 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.
Local SYSTEMTIME or FILETIME A system time or file time converted to the system's local time zone.
File FILETIME The number of 100-nanosecond intervals since January 1, 1601.
MS-DOS WORD A packed word for the date, another for the time.
Windows DWORD or ULONGLONG The number of milliseconds since the system was last started. When retrieved as a DWORD value, Windows time cycles every 49.7 days.
Interrupt Count ULONGLONG The number of 100-nanosecond intervals since the system was last started.

 

For more information, see the following topics: