function DayOfTheWeek(const AValue: TDateTime): Word;
unsigned short __fastcall DayOfTheWeek(System::TDateTime AValue);
Returns the day of the week represented by a TDateTime value.
Call DayOfTheWeek to obtain the day of the week represented by a specified TDateTime value. DayOfTheWeek returns a value from 1 through 7, where 1 indicates Monday and 7 indicates Sunday.
Note: DayOfTheWeek is ISO 8601 compliant (where Monday is considered the first day of the week). To obtain the day of the week, where Sunday is considered the first day of the week, use the DayOfWeek function instead.
Tip: To make the return value more readable, use the day of week constants.