Delphi Issameday, Istoday Function-judge is not the same day, judge is not today

unit　Unit1;

interface

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

type
　TForm1　=　class(TForm)
　　procedure　FormCreate(Sender:　TObject);
　end;

var
　Form1:　TForm1;

implementation

{$R　*.dfm}

uses　DateUtils;

procedure　TForm1.FormCreate(Sender:　TObject);
var
　t1,t2,t3,t4:　TDateTime;
　b:　Boolean;
begin
　t1　:=　StrToDateTime('2009-1-21');
　t2　:=　StrToDateTime('2009-1-21');
　t3　:=　StrToDateTime('2009-5-21');
　t4　:=　Now;

　{判断是不是同一天}
　b　:=　IsSameDay(t1,　t2);　//True
　b　:=　IsSameDay(t1,　t3);　//False

　{判断给定时间和当前时间是不是同一天}
　b　:=　IsToday(t1);　//False
　b　:=　IsToDay(t4);　//True

//　ShowMessage(BoolToStr(b,　True));
end;

end.