Somar total de horas entre 2 datas

[Jhonas]

OBS: o comando SecondsBetween é do Delphi 7

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure FormActivate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses DateUtils;

{$R *.dfm}

//Função converter Segundos para Horas

function Seg_Hora( Seg:LongInt ):string;
Var Hora,Min:LongInt;
  Tmp : Double;
begin
   Tmp := Seg / 3600;
   Hora := Round(Int(Tmp));
   Seg :=  Round(Seg - (Hora*3600));
   Tmp := Seg / 60;
   Min := Round(Int(Tmp));
   Seg :=  Round(Seg - (Min*60));
   Result := FormatFloat( '00', Hora )+ ':' + FormatFloat( '00', Min ) + ':' + FormatFloat( '00', Seg );
end;


procedure TForm1.Button1Click(Sender: TObject);
var total : int64; ini, fim : TDateTime;
begin
   ini := strtodatetime(Edit1.Text);
   fim := strtodatetime(Edit2.Text);

   total := SecondsBetween(ini,fim);
   Label1.Caption := 'Tempo Total : '+ seg_hora(total);
end;

procedure TForm1.FormActivate(Sender: TObject);
begin
   edit1.Text := '13/10/2010 13:25:10';
   edit2.Text := '14/10/2010 15:33:15';
end;

end.

abraço