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• #47 Rover623 félisten

  2005-03-03 00:48:41 #47

  Összes hozzászólása itt Válaszok az összes hozzászólására itt Válaszok erre a hozzászólásra

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  Rover623

  félisten

  Itt egy másik megoldás a Dr Dobbs Journal-ból, 1990-ből...
  Egy Zeller nevű csóka algoritmusa 1887-ből...!
  Felhívom a figyelmet az angol nyelvű kommentekre:
  { Here's Zeller's seminal black magic: }
  { DON'T KNOW WHY HE DID THIS! }
  
  Function CalcDayOfWeek(Year, Month, Day : Integer) : Integer;
  Var
  Century,
  Holder : Integer;
  begin
  { First test For error conditions on input values: }
  if (Year < 0) or (Month < 1) or (Month > 12) or (Day < 1) or (Day > 31) then
  CalcDayOfWeek := -1 { Return -1 to indicate an error }
  else
  { Do the Zeller's Congruence calculation as Zeller himself }
  { described it in ''Acta Mathematica'' #7, Stockhold, 1887. }
  begin
  { First we separate out the year and the century figures: }
  Century := Year div 100;
  Year := Year MOD 100;
  { Next we adjust the month such that March remains month #3, }
  { but that January and February are months #13 and #14, }
  { *but of the previous year*: }
  if Month < 3 then
  begin
  Inc(Month, 12);
  if Year > 0 then
  Dec(Year, 1) { The year before 2000 is }
  else { 1999, not 20-1... }
  begin
  Year := 99;
  Dec(Century);
  end;
  end;
  
  { Here's Zeller's seminal black magic: }
  Holder := Day; { Start With the day of month }
  Holder := Holder + (((Month + 1) * 26) div 10); { Calc the increment }
  Holder := Holder + Year; { Add in the year }
  Holder := Holder + (Year div 4); { Correct For leap years }
  Holder := Holder + (Century div 4); { Correct For century years }
  Holder := Holder - Century - Century; { DON'T KNOW WHY HE DID THIS! }
  {***********************KLUDGE ALERT!***************************}
  While Holder < 0 do { Get negative values up into }
  Inc(Holder, 7); { positive territory before }
  { taking the MOD... }
  Holder := Holder MOD 7; { Divide by 7 but keep the }
  { remainder rather than the }
  { quotient }
  {***********************KLUDGE ALERT!***************************}
  { Here we ''wrap'' Saturday around to be the last day: }
  if Holder = 0 then
  Holder := 7;
  
  { Zeller kept the Sunday = 1 origin; computer weenies prefer to }
  { start everything With 0, so here's a 20th century kludge: }
  Dec(Holder);
  
  CalcDayOfWeek := Holder; { Return the end product! }
  end;
  end;
  
  Szóval nem egyértelmű...ja, ez 1582 és 4902 között műx
  
  [Szerkesztve]

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