请教个关于计时的问题

ufo20020427 2005-09-26 11:53:42

unit Unit1;

interface

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

type
TForm1 = class(TForm)
Button1: TButton;
Edit1: TEdit;
Button2: TButton;
Button3: TButton;
Timer1: TTimer;
Edit2: TEdit;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
procedure Timer1Timer(Sender: TObject);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
n:integer;
implementation

{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject); ／／数学运算
var i:integer;
d:integer;
begin
d:=50;
n:=1;
timer1.Enabled:=true;
for i:=1 to 90000000 do begin
d:=d*2;
d:=trunc(d/2); end;
timer1.enabled:=false;
edit1.text:=floattostr(d);
edit2.text:=inttostr(n); //显示所用时间

end;

procedure TForm1.Button2Click(Sender: TObject);　　／／位运算
var i:integer;
d:integer;
begin
d:=50;
n:=1;
timer1.Enabled:=true;
for i:=1 to 90000000 do begin
d:=(d shl 1);
d:=(d shr 1); end;
timer1.enabled:=false;
edit1.text:=inttostr(d);
edit2.text:=inttostr(n); //显示所用时间

end;

procedure TForm1.Button3Click(Sender: TObject);
begin
edit1.Text:='';
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
inc(n);
edit2.text:=inttostr(n);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
timer1.Enabled:=false;
end;

end.
我是在试验　位运算比数学运算快多少
但是为何edit2.text:=inttostr(n); //显示所用时间　的最终结果总是１呢？
我把timer1的Inteval改为20、200等结果都是１
这是怎么回事呢，谢谢！

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hellolongbin 2005-09-27

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hellolongbin 2005-09-26

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计算这么精确的时间，用timer显然是行不通的

procedure TForm1.Button1Click(Sender: TObject);
var i:integer;
d:integer;
begin
edit1.text:=FormatDateTime('yyyymmddhhmmsszzz',now);
for i:=1 to 90000000 do begin
d:=d*2;
d:=trunc(d/2); end;
edit2.text:=FormatDateTime('yyyymmddhhmmsszzz',now);
end;