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DayOfWeek ​

DayOfWeek returns the day of the week represented by the TDateTime value specified by AValue.

You would use DayOfWeek to obtain the ordinal position of day within its week, where 1 indicates a Sunday, and 7 indicates a Saturday.

INFO

DayOfWeek is not ISO 8601 compliant, so Sunday is considered the first day of the week.

To obtain the day of the week, where Monday is considered the first day of the week, use the DayOfTheWeek function instead. Please review DayOfTheWeek.

Declaration: function DayOfWeek(const AValue: TDateTime): Word;

A code example follows.

pascal
procedure OnMapEvent(var Value:Variant);
var
  TheDay : word;
begin
 //If YESTERDAY is 29-11-2023 then the result is 4 (Wednesday)
  TheDay := DayOfWeek(Yesterday);
  LogInfo('The day number for Wednesday 29-11-2023 (Sunday-based) is '+IntToStr(TheDay));
end;