Delphi实现判断日期的合法性函数

unit Unit37;

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

    function IsValidDate(const AYear, AMonth, ADay: Word): Boolean;

implementation

function IsValidDate(const AYear, AMonth, ADay: Word): Boolean;
begin
if ((AYear<10000)and(AYear>0)and(AMonth>0)and(AMonth<13))then
begin
  if((AMonth=1)or(AMonth=1)or(AMonth=1)or(AMonth=1)or(AMonth=1)or(AMonth=1)or(AMonth=1))then
    begin
      if((ADay>0)and(ADay<32))then
         IsValidDate:=true
      else
         IsValidDate:=false;
    end
  else if((AMonth=4)or(AMonth=6)or(AMonth=9)or(AMonth=11))then
    begin
      if((ADay>0)and(ADay<31))then
         IsValidDate:=true
      else
         IsValidDate:=false;
    end
  else if(AMonth=2)then
    begin
      if((AYear mod 400=0)and(ADay>0)and(ADay<30))or((AYear mod 400<>0)and(ADay>0)and(ADay<29))then
         IsValidDate:=true
      else
         IsValidDate:=false;
    end;
end
else
  IsValidDate:=false;
end;

end.