YearsBetween、MonthsBetween ... YearSpan、MonthSpan ... 間隔

DateUtils.YearsBetween();
DateUtils.MonthsBetween();
DateUtils.WeeksBetween();
DateUtils.DaysBetween();
DateUtils.HoursBetween();
DateUtils.MinutesBetween();
DateUtils.SecondsBetween();
DateUtils.MilliSecondsBetween();
DateUtils.YearSpan();
DateUtils.MonthSpan();
DateUtils.WeekSpan();
DateUtils.DaySpan();
DateUtils.HourSpan();
DateUtils.MinuteSpan();
DateUtils.SecondSpan();
DateUtils.MilliSecondSpan();

unit Unit1;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;
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: TDateTime;
  i: Int64;
  d: Double;
begin
  t1 := StrToDateTime('2009-5-20 11:22:33');
  t2 := StrToDateTime('2020-9-21 22:33:44');
  i := YearsBetween(t1, t2);        //11
  i := MonthsBetween(t1, t2);       //136
  i := WeeksBetween(t1, t2);        //591
  i := DaysBetween(t1, t2);         //4142
  i := HoursBetween(t1, t2);        //99419
  i := MinutesBetween(t1, t2);      //5965151
  i := SecondsBetween(t1, t2);      //357909071
  i := MilliSecondsBetween(t1, t2); //357909070999
  i := YearsBetween(t2, t1);        //11, 參數無先後
  {下面這個系列返回的時間間隔是 Double 類型的, 更精確}
  d := YearSpan(t1, t2);        //11.3414540712855
  d := MonthSpan(t1, t2);       //136.097448855426
  d := WeekSpan(t1, t2);        //591.780871362434
  d := DaySpan(t1, t2);         //4142.46609953704
  d := HourSpan(t1, t2);        //99419.1863888889
  d := MinuteSpan(t1, t2);      //5965151.18333333
  d := SecondSpan(t1, t2);      //357909071
  d := MilliSecondSpan(t1, t2); //357909071000
end;
end.