unit1.pas

很好地delphi书籍源码

unit Unit1;

interface

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

type
  TSchool=class
  public
   Name:string;
   function GetKind:string;virtual;
  end;

  THighSchool=class(TSchool)
  public
    ClassCounts:Word;
    function GetKind:string;override;
  end;

  TUniversity=class(TSchool)
    facultyCounts:word;
    function GetKind:string;override;
  end;

  TForm1 = class(TForm)
    RadioButton1: TRadioButton;
    RadioButton2: TRadioButton;
    RadioButton3: TRadioButton;
    Button1: TButton;
    procedure RadioButton1Click(Sender: TObject);
    procedure RadioButton2Click(Sender: TObject);
    procedure RadioButton3Click(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    AScool:TSchool;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TSchool }

function TSchool.GetKind: string;
begin
  GetKind:='一所学校';
end;

function THighSchool.GetKind: string;
begin
  GetKind:='一所中学';
end;

function TUniversity.GetKind: string;
begin
  GetKind:='一所大学';
end;

procedure TForm1.RadioButton1Click(Sender: TObject);
begin
  AScool:=TSchool.Create;
end;

procedure TForm1.RadioButton2Click(Sender: TObject);
begin
  AScool:=THighSchool.Create;
end;

procedure TForm1.RadioButton3Click(Sender: TObject);
begin
  AScool:=TUniversity.Create;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Caption:=AScool.GetKind;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  RadioButton1Click(self);
  RadioButton1.Checked:=true;
end;

end.