### Search

 Search WWW Search DelphiForFun.org

As of October, 2016, Embarcadero is offering a free release of Delphi (Delphi 10.1 Berlin Starter Edition ).     There are a few restrictions, but it is a welcome step toward making more programmers aware of the joys of Delphi.  They do say "Offer may be withdrawn at any time", so don't delay if you want to check it out.  Please use the feedback link to let me know if the link stops working.

Support DFF - Shop

If you shop at Amazon anyway,  consider using this link.

We receive a few cents from each purchase.  Thanks

### Support DFF - Donate

If you benefit from the website,  in terms of knowledge, entertainment value, or something otherwise useful, consider making a donation via PayPal  to help defray the costs.  (No PayPal account necessary to donate via credit card.)  Transaction is secure.

Mensa® Daily Puzzlers

For over 15 years Mensa Page-A-Day calendars have provided several puzzles a year for my programming pleasure.  Coding "solvers" is most fun, but many programs also allow user solving, convenient for "fill in the blanks" type.  Below are Amazon  links to the two most recent years.

(Hint: If you can wait, current year calendars are usually on sale in January.)

### Contact

 Search DelphiForFun.org only

```unit U_Easter;

{Calculates the date of Easter given any year.  I don't pretend to understand
the details of the algorithm.  It comes from the Art Of Programming series
of books by Donald Knuth}

{Gary Darby, www.dephiforfun.org}

interface

{..... generated code snipped ....}

implementation

Function KnuthCalcEaster(year:integer; var easter:TDateTime):String;
{From Vol 3 of The Art of Computer Programming, Donlad E. Knuth}
var
golden,century:integer;
Correction1,Correction2:integer;
Sunday,Epact:Integer;
N:Integer;
begin
If Year <= 1582 then
Showmessage('OK, but  results are only valid for years after 1582');
Golden := Year mod 19  + 1 ;
Century := Year div 100 + 1 ;
Correction1 := trunc(3.0 * Century / 4.0) - 12;
Correction2 := trunc((8.0 * Century + 5.0) / 25.0) - 5;
Sunday := trunc(5.0 * year / 4.0) - Correction1 -10 ;
Epact := (11 * Golden + 20 + Correction2 - Correction1) mod 30 ;
IF ((Epact = 25) and (Golden > 11))  or (Epact = 24) then
Epact := Epact + 1 ;
N := 44 - Epact;
if N < 21 then  N := N + 30 ;
N := N + 7 - ((Sunday + N) mod 7) ;
try
{Pass a Year, Month, and Day and get a date back}
easter:=encodedate(year,3,1)+n-1;
result:=FormatDateTime('mmmm d',easter);
except
showmessage(inttostr(year)+' is an invalid year');
result:='';
easter:=0;
end;
end;

Procedure TForm1.getdate(Year:integer);
{take a year, calculate Easter date and display it}
var
iswas:string;
s:string;
Easter:TDateTime;
begin
s:=Knuthcalceaster(year,Easter);
If easter>now then iswas:=' will be on '
else iswas:=' was on ';
Easter2lbl.Caption:='Easter in '+inttostr(year)
+ iswas +s;
Intedit1.text:=inttostr(year);
end;

procedure TForm1.IntEdit1KeyPress(Sender: TObject; var Key: Char);
{Get integers and show Easter when Enter key is pressed}
begin
If key=#13 then
begin
Getdate(strtoint(IntEdit1.text));
key:=#00;
end
else if not (key in ['0'..'9']) then
begin  beep;  key:=#00; end;
end;

procedure TForm1.FormActivate(Sender: TObject);
var
y,m,d:word;
m2,d2:integer;
e1,e2:TDateTime;
s1,s2:string;
begin
{set current data at start up time}
decodedate(now,y,m,d);
getdate(y);
end;

procedure TForm1.IntEdit1Click(Sender: TObject);
begin {also show Easter if year is clicked}
getdate(strtoint(intedit1.text));
end;

end.

```