《Delphi 演算法與資料結構》學習與感悟[10]: 雙向鏈表

如果在結構中再拿出 4 個位元組的地址空間指向上一個節點, 就成了雙向鏈表了.

本例:

unit Unit1;interfaceuses  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;  MyRec = record    Name: string[8];    Age : Word;    Prev,Next: PMyRec; {上一個與下一個的結構指標}  end;var  CurrentNode: PMyRec;{建立雙向鏈表}procedure TForm1.FormCreate(Sender: TObject);var  PrevNode: PMyRec;  i: Integer;begin  PrevNode := nil;  for i := 65 to 71 do  {建七個節點, 準備用 AA, BB, CC, DD, EE, FF, GG 來指定 MyRec.Name }  begin    New(CurrentNode);    CurrentNode.Name := Chr(i) + Chr(i);    CurrentNode.Age := i;    CurrentNode.Prev := PrevNode;    if Assigned(PrevNode) then PrevNode.Next := CurrentNode;    PrevNode := CurrentNode;  end;  Button1.Caption := '上一個';  Button2.Caption := '下一個';end;{上一個}procedure TForm1.Button1Click(Sender: TObject);begin  if Assigned(CurrentNode.Prev) then  begin    CurrentNode := CurrentNode.Prev;    Text := CurrentNode.Name + #44 + IntToStr(CurrentNode.Age);  end else Text := '這是第一個節點';end;{下一個}procedure TForm1.Button2Click(Sender: TObject);begin  if Assigned(CurrentNode.Next) then  begin    CurrentNode := CurrentNode.Next;    Text := CurrentNode.Name + #44 + IntToStr(CurrentNode.Age);  end else Text := '這是最後一個節點';end;end.