TDateTime is the data type used in VCL and CLX for representing date
and time values. In Delphi, TDateTime is a type that maps to a Double and
represents date and time together in a single compact value. Its integral
part is used for storing date and its fractional part is used for time.
The Gregorian calendar is used for implementing date-time support
in Delphi. Despite TDateTime is independent of calendar type and its
calculations. These are encode and decode functions that play the main role.
ShDateUtils unit makes it possible to use
TDateTime with Hijri Shamsi date by implementing these functions for Jalali
(Hijri Shamsi) calendar.
- type TDateTime = type Double;
- The integral part of a TDateTime value is the number of days
that have passed since 12/30/1899 corresponds to 1278/10/09. The
fractional part of a TDateTime value is fraction of a 24-hour day that
- Some examples of TDateTime values and their
corresponding dates and times:
12/30/1899 12:00 am 1278/10/09
01/01/1900 06:00 pm 1278/10/11 06:00 pm
12/29/1899 06:00 am
1278/10/08 06:00 am
01/01/1996 12:00 am
1374/10/11 12:00 am