unit1.pas

自动求出任何一个数值的sin值。可自动保留有效数字。

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Label1: TLabel;
    Edit2: TEdit;
    Button1: TButton;
    Edit3: TEdit;
    Label2: TLabel;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Edit1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  flag:integer;
implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
x,n,j,s1,s2,s3:integer;
s:real;

begin
x:=strtoint(edit1.text);
n:=strtoint(edit2.text);
if n<3 then
begin
   showmessage('输入错误,N>2');
   edit2.Text:='';
end
else
begin
s:=0;
s1:=1;  s2:=x;   s3:=1;
for  j:=2 to n do
begin

     s1:=s1*(-1);

     s2:=s2*x*x;

     s3:=s3*(2*j-2)*(2*j-1);

 s:=s+(s1*s2/s3);

end;
s:=s+x;
edit3.text:=floattostr(s);
end;
end;
procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
if ((key>'/') and( key<':')) or (key=#13)then
else
begin
showmessage('输入X错误!');
edit1.Text:='';
flag:=1;
end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
close;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
flag:=0;
end;

procedure TForm1.Edit1Change(Sender: TObject);
begin
if flag=1 then edit1.Text:='';
end;

end.