unit kalendar;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;


type
  Tdate = class
   d : byte;      
   m : byte;      
   y : integer;  
  end;

  Tstyle = (grigorian, julian);

function numofday(dat : tdate; style : tstyle) : longint;
function  dayofweek(dat : tdate; style : tstyle) : byte;
function lenofmonth(month : byte; year : word; style : tstyle) : byte;
function isleap(year : integer):boolean;  

type
  TForm1 = class(TForm)
    
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation


{***************************************************************************}

  function numofday;
     var
          stcor : integer;
     begin

          if style = grigorian then
               begin
                    stcor := 2-dat.y div 100+dat.y div 400;
                    if ((dat.y mod 100 = 0) and (dat.y mod 400 <> 0)) and (dat.m <= 2) then stcor := stcor + 1;
               end
                               else
               begin
                    stcor := 0;
               end;

          inc(dat.m);

          if dat.m <= 3 then
               begin
                    dat.m := dat.m+12;
                    dec(dat.y);
               end;
          numofday := (36525*dat.y) div 100 + (306*dat.m) div 10 + stcor + dat.d;
     end;

{***************************************************************************}

  function dayofweek;
     var

          day                 : byte;
          buf                 : longint;
     begin
          buf := numofday(dat, style);
          buf := buf+4;
          day := buf mod 7;
       if day = 0 then day := 7;
          dayofweek := day;
     end;

{***************************************************************************}

function lenofmonth;
     var
          len                 : byte;
     begin
          case month of
               2 : begin
                        if year mod 4 = 0 then len := 29
                                          else len := 28;
                        if (style = grigorian) and (year mod 100 = 0) and (year mod 400 > 0) then len := 28;
                   end;
               4, 6, 9, 11 : len := 30
               else len := 31;
          end;
          lenofmonth := len;
     end;

{***************************************************************************}

function isleap;
     begin
          isleap := (((year mod 4 = 0) and (year mod 100 <> 0)) or (year mod 400 = 0));
     end;


end.