Start- und Enddatum einer Kalenderwoche ermitteln

[negaH]

Delphi-Quellcode:

function WeekOfDate(ADate: TDateTime): Integer;
var
  Day: Integer;
  Y,M,D: Word;
begin
  Day := DayOfWeekGerman(ADate);
  DecodeDate(ADate +4 -Day, Y, M, D);
  Result := Round(((ADate +8 -Day) - EncodeDate(Y, 1, 1)) / 7);
end;

function DateOfWeek(AYear, AWeek: Word): TDateTime;
begin
  Result := EncodeDate(AYear, 1, 1);
  Result := Result - (DayOfWeek(Result -2) +3) mod 7 +3 + (AWeek -1) * 7;
end;

function WeeksOfYear(AYear: Word): Integer;
var
  D: TDateTime;
begin
  D := EncodeDate(AYear+1, 1, 1);  // 1.1. des folgenden Jahres
  Result := WeekOfDate(D);         // KW 
  if Result = 1 then
  begin
    D := D - 7;                    // 1 KW zurück
    Result := WeekOfDate(D);
  end;
end;

function DayOfWeekGerman(ADate: TDateTime): Integer;
begin
  Result := DayOfWeek(ADate) -1;
  if Result <= 0 then Result := 7;
end;

function WeekStart(ADate: TDateTime; German: Boolean): TDateTime;
begin
  if German then Result := ADate - (DayOfWeekGerman(ADate) -1)
    else Result := ADate - (DayOfWeek(ADate) -1);
end;

WeekOfDate() ist die Funktion die du suchst.

Gruß Hagen