This function converts the variant representation of time to system time values.
Passing invalid (and under some circumstances NULL) pointers to this function causes an unexpected termination of the application.
A variant time is stored as an 8-byte real value (double), representing a date between January 1, 1753 and December 31, 2078, inclusive.
The value 2.0 represents January 1, 1900; 3.0 represents January 2, 1900, and so on.
Adding 1 to the value increments the date by a day. The fractional part of the value represents the time of day. Therefore, 2.5 represents noon on January 1, 1900; 3.25 represents 6:00 A.M. on January 2, 1900, and so on.
Negative numbers represent the dates prior to December 30, 1899.
Using the SYSTEMTIME structure is useful for these reasons:
It spans all time/date periods. MS-DOS date/time is limited to representing only those dates between 1/1/1980 and 12/31/2107.
The date/time elements are all easily accessible without needing to do bit decoding.
The National Language Support data and time formatting functions GetDateFormat and GetTimeFormat take a SYSTEMTIME value as input.
It is the default Win32 time and date data format supported by Windows NT and Windows 95.