날짜를 처리하는 함수 모음 

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, 

Dialogs,

StdCtrls;

type

TDayOfWeek = 

(Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday);

type

TForm1 = class(TForm)

private

{ Private declarations }

public

{ Public declarations }

function dateYear(D: TDateTime): Integer;

function dateMonth(D: TDateTime): Integer;

function dateDay(D: TDateTime): Integer;

function dateBeginOfYear(D: TDateTime): TDateTime;

function dateEndOfYear(D: TDateTime): TDateTime;

function dateBeginOfMonth(D: TDateTime): TDateTime;

function dateEndOfMonth(D: TDateTime): TDateTime;

function dateWeekOfYear(D: TDateTime): Integer;

function dateDayOfYear(D: TDateTime): Integer;

function dateDayOfWeek(D: TDateTime): TDayOfWeek;

function dateLeapYear(D: TDateTime): Boolean;

function dateBeginOfQuarter(D: TDateTime): TDateTime;

function dateEndOfQuarter(D: TDateTime): TDateTime;

function dateBeginOfWeek(D: TDateTime;Weekday: Integer): 

TDateTime;

function dateDaysInMonth(D: TDateTime): Integer;

end;

var

Form1: TForm1;

implementation

{$R *.DFM}

// 날짜의 년도만 발취

function TForm1.dateYear(D: TDateTime): Integer;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := Year;

end;

// 날짜의 월만 발취

function TForm1.dateMonth(D: TDateTime): Integer;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := Month;

end;

// 날짜의 일만 발취

function TForm1.dateDay(D: TDateTime): Integer;

var

Year,Month,Day : Word;

begin

DecodeDate (D,Year,Month,Day);

Result := Day;

end;

// 년의 시작일자

function TForm1.dateBeginOfYear(D: TDateTime): TDateTime;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := EncodeDate(Year, 1, 1);

end;

// 년의 마지막일자

function TForm1.dateEndOfYear(D: TDateTime): TDateTime;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := EncodeDate(Year, 12, 31);

end;

// 월의 시작일자

function TForm1.dateBeginOfMonth(D: TDateTime): TDateTime;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := EncodeDate(Year, Month, 1);

end;

// 월의 마지막일자

function TForm1.dateEndOfMonth(D: TDateTime): TDateTime;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

if Month = 12 then

begin

Inc(Year);

Month := 1;

end

else

Inc(Month);

{월의 다음월의 시작일에서 1을 뺀다}

Result := EncodeDate(Year, Month, 1) - 1;

end;

// 년을 기준으로 몇번째 주인지

function TForm1.dateWeekOfYear(D: TDateTime): Integer;

const

t1: array[1..7] of ShortInt = ( -1, 0, 1, 2, 3, -3, -2);

t2: array[1..7] of ShortInt = ( -4, 2, 1, 0, -1, -2, -3);

var

doy1, doy2: Integer;

NewYear: TDateTime;

begin

NewYear := dateBeginOfYear(D);

doy1 := dateDayofYear(D) + t1[DayOfWeek(NewYear)];

doy2 := dateDayofYear(D) + t2[DayOfWeek(D)];

if doy1 <= 0 then

Result := dateWeekOfYear(NewYear-1)

else if (doy2 >= dateDayofYear(dateEndOfYear(NewYear))) then

Result:= 1

else

Result:=(doy1-1) div 7+1;

end;

// 년을 기준으로 몇번째 일인지

function TForm1.dateDayOfYear(D: TDateTime): Integer;

begin

Result := Trunc(D-dateBeginOfYear(D)) + 1;

end;

// 요일 번호

function TForm1.dateDayOfWeek(D: TDateTime): TDayOfWeek;

begin

Result := TDayOfWeek(Pred(DayOfWeek(D)));

end;

// 윤년인지 검사

function TForm1.dateLeapYear(D: TDateTime): Boolean;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := (Year mod 4 = 0) and ((Year mod 100 <> 0) or (Year mod 400 

= 0));

end;

// 주어진 일자가 포함된 분기의 시작일

function TForm1.dateBeginOfQuarter(D: TDateTime): TDateTime;

var

Year, Month, Day: Word;

begin

DecodeDate(D, Year, Month, Day);

Result := EncodeDate(Year, (((Month-1) div 3) * 3)+1, 1);

end;

// 주어진 일자가 포함된 분기의 마지막일

function TForm1.dateEndOfQuarter(D: TDateTime): TDateTime;

begin

Result := dateBeginOfQuarter(dateBeginOfQuarter(D)+(3*31)) - 1;

end;

// 주의 시작일

function TForm1.dateBeginOfWeek(D: TDateTime; Weekday: Integer): 

TDateTime;

begin

Result := D;

while DayOfWeek(Result) <> Weekday do

Result := Result - 1;

end;

// 월의 마지막 일

function TForm1.dateDaysInMonth(D: TDateTime): Integer;

const

DaysPerMonth: array[1..12] of Byte= 

(31,28,31,30,31,30,31,31,30,31,30,31);

var

Month: Integer;

begin

Month := dateMonth(D);

Result := DaysPerMonth[Month];

if (Month=2) and dateLeapYear(D) then

Inc(Result);

end;

end.