請問: 如何以Delphi作某日為全年第幾週之判斷 謝謝

function WeekOfYear(ADate: TDateTime): word;
var
  d, m, y: word;
  FirstOfYear: TDateTime;
begin
  DecodeDate(ADate, y, m, d);
  FirstOfYear := EncodeDate(y, 1, 1);
  Result := Trunc(ADate - FirstOfYear) div 7   1;
end;
   
procedure TForm .Button Click(Sender: TObject);
begin
  ShowMessage(IntToStr(WeekOfYear(Date)));
end;

--- 每個人都是一本書

From delphi help: WeekOfTheYear function Returns the week of the year represented by a TDateTime value. Unit DateUtils Category datetime routines Delphi syntax: function WeekOfTheYear(const AValue: TDateTime): Word; overload; function WeekOfTheYear(const AValue: TDateTime; var AYear): Word; overload; C syntax: extern PACKAGE Word __fastcall WeekOfTheYear(const System::TDateTime AValue); extern PACKAGE Word __fastcall WeekOfTheYear(const System::TDateTime AValue, Word &AYear); Description Call WeekOfTheYear to obtain the week of the year represented by a specified TDateTime value. WeekOfTheYear returns a value between 1 and 53. AYear returns the year in which the specified week occurs. Note that this may not be the same as the year of AValue. This is because the first week of a year is defined as the first week with four or more days in that year. This means that if the first calendar day of the year is a Friday, Saturday, or Sunday, then for the first three, two, or one days of the calendar year, WeekOfTheYear returns the last week of the previous year. Similarly, if the last calendar day of the year is a Monday, Tuesday, or Wednesday, then for the last one, two, or three days of the calendar year, WeekOfTheYear returns 1 (the first week of the next calendar year). Note: WeekOfTheYear uses the ISO 8601 standard definition of a week. That is, a week is considered to start on a Monday and end on a Sunday. Note: WeekOfTheYear returns the same value as the WeekOf function.

uses DateUtils; WeekOfTheYear(Date);