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Hijri Date Conversion Unit - Delphi Source Code

Monday, March 23, 2009

Here’s a little Hijri calendar conversion unit that I wrote a few years ago. I converted this from a JavaScript that I found on a website.
Hope this would be useful to you.
// Created by Irwan A. 
// irwan.a@gmail.com 
// 
// adapted from a Javascript source code that 

// i found somewhere on the net. 
// but i lost the URL. hope the author doesn't mind :) 
// Month & day names are taken from 
// http://en.wikipedia.org/wiki/Islamic_calendar 
// thanks to @bu @hs@n  
// for pointing this out 

unit Hijri; 

interface 

uses 
Windows, Messages, SysUtils, Classes, Graphics, 
Controls, Math; 

type 
THijriDate = record 
HijriDate: integer; 
HijriMonth: integer; 
HijriYear: integer; 
JulianDate: integer; 
HijriDay: string; 
end; 

function IntPart(Num : real) : integer; 
function WeekDay(Wdn : integer) : string; 
function Gre2Hijri(var D, M, Y : word): THijriDate; 
function HijriMonths(Mth : integer) : string; 

implementation 

function IntPart(Num : real) : integer; 
begin 
if Num < -0.0000001 then 
Result := Ceil(Num - 0.0000001) 
else 
Result := Floor(Num + 0.0000001); 
end; 

function WeekDay(Wdn : integer) : string; 
begin 
case Wdn of 
0: Result := 'Al-Ithnayn'; 
1: Result := 'Ath-Thalatha'; 
2: Result := 'Al-Arba`a'; 
3: Result := 'Al-Khamis'; 
4: Result := 'Al-Jum`a'; 
5: Result := 'As-Sabt'; 
6: Result := 'Al-Ahad'; 
end; 
end; 

function Gre2Hijri(var D, M, Y : word): THijriDate; 
var 
jd, l, n, j : integer; 
begin 
if ((Y > 1582) or ((Y = 582) and (M > 10)) 
or ((Y = 1582) and (M = 10) and (D>14))) then 
begin 
jd := IntPart((1461 * (Y + 4800 + 
IntPart((M - 14)/12)))/4) + 
IntPart((367 * (M - 2 - 12 * 
(IntPart((M - 14)/12))))/12) - 
IntPart((3 * (IntPart((Y + 4900 + 
IntPart((M - 14)/12))/100)))/4) + D - 32075; 
end 
else 
begin 
jd := 367 * Y - IntPart((7 * (Y + 5001 + 
IntPart((M - 9)/7)))/4) + IntPart((275 * M)/9) 
+ D + 1729777; 
end; 

l := jd -1948440 + 10632; 
n := IntPart((l - 1)/10631); 
l := l - 10631 * n + 354; 

j := (IntPart((10985 - l)/5316)) * 
(IntPart((50 * l)/17719)) + (IntPart(l/5670)) * 
(IntPart((43 * l)/15238)); 

l := l - (IntPart((30 - j)/15)) * 
(IntPart((17719 * j)/50)) - (IntPart(j/16)) * 
(IntPart((15238 * j)/43)) + 29; 

m := IntPart((24 * l)/709); 
d := l - IntPart((709 * m)/24); 
y := 30 * n + j - 30; 

Result.HijriDate := d; 
Result.HijriMonth := m; 
Result.HijriYear := y; 
Result.JulianDate := jd; 
Result.HijriDay := WeekDay(jd mod 7); 

end; 

function HijriMonths(Mth : integer) : string; 
begin 
case Mth of 
1: Result := 'Muharram'; 
2: Result := 'Safar'; 
3: Result := 'Rabi'' al-awwal'; 
4: Result := 'Rabi'' al-thani'; 
5: Result := 'Jumada al-awwal'; 
6: Result := 'Jumada al-thani'; 
7: Result := 'Rajab'; 
8: Result := 'Sha''ban'; 
9: Result := 'Ramadan'; 
10: Result := 'Shawwal'; 
11: Result := 'Dhu al-Qi''dah'; 
12: Result := 'Dhu al-Hijjah'; 
end; 
end; 

end.

Note:
As the hijri calendar is based on the lunar movement, the dates calculated using this code may be off +1/-1 day from the actual date. When determining the beginning of the Ramadan or Shawwal (or other important dates), please consult the local authorities for such matter.

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