unit1.pas

本光盘是《Delphi 7应用教程》一书的配套光盘

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    Label1: TLabel;
    Label2: TLabel;
    Button1: TButton;
    procedure ButtonDisplayClick(Sender: TObject);
    procedure ButtonCloseClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.ButtonDisplayClick(Sender: TObject);
begin
  Label1.Caption:='Delphi7.0欢迎您！';//将这句话赋值给标签的标题属性
end;

procedure TForm1.ButtonCloseClick(Sender: TObject);
begin
  Application.Terminate; //应用程序关闭
end;

procedure TForm1.FormCreate(Sender: TObject);

begin

end;                      //程序结束

procedure TForm1.Button1Click(Sender: TObject);
var
  a,b,t:Real;                //定义三个实型变量
begin
 a:=strtofloat(edit1.Text);
 b:=strtofloat(edit2.Text );
 if (a>b) then   //如果a大于b（否则，直接转到最后一个"end;"语句，程序结束）
   begin       //执行下面的复合语句
     t:=a;                //将a赋值给t
     a:=b;                //将b赋值给a
     b:=t;                //将t赋值给b（从而完成a和b交换的功能）
   end;
 Edit1.text:=floattostr(a);
 edit2.Text :=floattostr(b);
end;

end.