《Delphi 算法与数据结构》学习与感悟[6]: 一个简单的"单向链表"

unit Unit1;



interface



uses

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

  Dialogs, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    Button2: TButton;

    procedure FormCreate(Sender: TObject);

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



type

  PMyRec = ^MyRec;  {把 PMyRec 定义为下面 MyRec 结构的指针类型}

  MyRec = record

    Name: string[8];

    Age : Word;

    Link: PMyRec;   {结构中同时包含同类型的指针, 用于链接其他同类结构}

  end;



var

  R1,R2,R3,R4: MyRec;



{把 R1、R2、R3、R4 够建成一个环环相扣的"链", 这就是一个简单的"链表"}

procedure TForm1.FormCreate(Sender: TObject);

begin

  R4.Name := '李四';

  R4.Age  := 16;

  R4.Link := nil;



  R3.Name := '张三';

  R3.Age  := 61;

  R3.Link := @R4;



  R2.Name := '钱二';

  R2.Age  := 24;

  R2.Link := @R3;



  R1.Name := '赵一';

  R1.Age  := 42;

  R1.Link := @R2;

end;



{现在 , 通过 R1 即可以访问整个链; 但这个链是单向的, 所以叫"单向链表"}    

procedure TForm1.Button1Click(Sender: TObject);

begin

  ShowMessage(R1.Name); {赵一}

  ShowMessage(R1.Link^.Name); {钱二}

  ShowMessage(R1.Link^.Link^.Name); {张三}

  ShowMessage(R1.Link^.Link^.Link^.Name); {李四}

end;



{通过结构指针读取数据可以省略 ^; 所以 Button1Click 可以简写为:}

procedure TForm1.Button2Click(Sender: TObject);

begin

  ShowMessage(R1.Name); {赵一}

  ShowMessage(R1.Link.Name); {钱二}

  ShowMessage(R1.Link.Link.Name); {张三}

  ShowMessage(R1.Link.Link.Link.Name); {李四}

end;



end.