偶的第二个Delphi程序

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls;

type

TForm1 = class(TForm)

Label1: TLabel;

Label2: TLabel;

Button1: TButton;

Edit1: TEdit;

Button2: TButton;

procedure Button1Click(Sender: TObject);

procedure Button2Click(Sender: TObject);

private

{ Private declarations }

public

{ Public declarations }

end;

var

Form1: TForm1;

const pi=3.14159;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);

var r,c,s:real;

begin

if edit1.text='' then

showmessage('输入为空，请重新输入！') //如果没有输入数据 则提示

else

begin

r:=strtofloat(edit1.text);

c:=2*pi*r;

s:=pi*sqr(r);

label2.Caption:='该圆的周长是：'+floattostr(c)+chr(13)+'面积是：'+floattostr(s); //显示结果

end;

end;

procedure TForm1.Button2Click(Sender: TObject);

begin

form1.Close; //退出按钮的事件代码

end;

end.