unit2_24.pas

Delphi 面向对象程序设计 李俊平主编 课后习题

unit Unit2_24;

interface

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

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
  type
     week=(sun,mon,tue,wed,thu,fri,sat);

{$R *.dfm}
 function mday(day:week):string;
  begin
    case day of
       sun:mday:='星期天';
       mon:mday:='星期一';
       tue:mday:='星期二';
       wed:mday:='星期三';
       thu:mday:='星期四';
       fri:mday:='星期五';
       sat:mday:='星期六';
       end;

  end;
  procedure TForm1.FormCreate(Sender: TObject);
  var
     year,month,day:word;
   begin
        decodedate(date,year,month,day);
        edit1.Text:=format('%d年%d月%d日',[year,month,day]);
    end;

procedure TForm1.Button1Click(Sender: TObject);
var
   today,yesterday,tomorrow:week;
   n:integer;
begin
   n:=dayofweek(now);
   case n of
   1: today:=sun;
   2: today:=mon;
   3: today:=tue;
   4: today:=wed;
   5: today:=thu;
   6: today:=fri;
   7: today:=sat;
   end;
   if today=low(week)  then
   yesterday:=high(week)
   else
      yesterday:=pred(today);
   if today=high(week)  then
       tomorrow:=low(week)
   else
      tomorrow:=succ(today);
      button1.Caption:='昨天';
      button2.Caption:='今天';
      button3.Caption:='明天';
      case (Sender as Tbutton).Tag of
       1:  button1.Caption:='昨天是'+mday(yesterday);
       2:  button2.Caption:='今天是'+mday(today);
       3:  button3.Caption:='明天是'+mday(tomorrow);
       end;

end;

procedure TForm1.Button2Click(Sender: TObject);
begin
     Form1.Button1Click(Sender);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
     Form1.Button1Click(Sender);
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
  close;
end;

end.