1. 一個簡單的
type
PMyRec = ^MyRec; {把 PMyRec 定義爲下面 MyRec 結構的指針類型}
MyRec = record
Name: string[8];
Age : Word;
Link: PMyRec; {結構中同時包含同類型的指針, 用於鏈接其他同類結構}
end;
var
R1,R2,R3,R4: MyRec;
{把 R1、R2、R3、R4 夠建成一個環環相扣的"鏈", 這就是一個簡單的"鏈表"}
procedure TForm1.FormCreate(Sender: TObject);
begin
R4.Name := '李四';
R4.Age := 16;
R4.Link :=
nil;
R3.Name := '張三';
R3.Age := 61;
R3.Link := @R4;
R2.Name := '錢二';
R2.Age := 24;
R2.Link := @R3;
R1.Name := '趙一';
R1.Age := 42;
R1.Link := @R2;
end;
{現在 , 通過 R1 即可以訪問整個鏈; 但這個鏈是單向的, 所以叫"單向鏈表"}
procedure TForm1.Button1Click(Sender: TObject);
begin
ShowMessage(R1.Name);
{趙一}
ShowMessage(R1.Link^.Name);
{錢二}
ShowMessage(R1.Link^.Link^.Name);
{張三}
ShowMessage(R1.Link^.Link^.Link^.Name);
{李四}
end;
{通過結構指針讀取數據可以省略 ^; 所以 Button1Click 可以簡寫爲:}
procedure TForm1.Button2Click(Sender: TObject);
begin
ShowMessage(R1.Name);
{趙一}
ShowMessage(R1.Link.Name);
{錢二}
ShowMessage(R1.Link.Link.Name);
{張三}
ShowMessage(R1.Link.Link.Link.Name
2.單向鏈表的添加、刪除與遍歷
implementation
{$R *.dfm}
type
PMyRec = ^MyRec;
MyRec = record
Name: string[8];
Age : Word;
Link: PMyRec;
end;
var
CurrentNode, FirstNode: PMyRec;
{建立鏈表}
procedure TForm1.FormCreate(Sender: TObject);
begin
New(FirstNode);
FirstNode.Name := '李四';
FirstNode.Age := 44;
FirstNode.Link :=
nil;
CurrentNode := FirstNode;
New(FirstNode);
FirstNode.Name := '張三';
FirstNode.Age := 33;
FirstNode.Link := CurrentNode;
CurrentNode := FirstNode;
New(FirstNode);
FirstNode.Name := '錢二';
FirstNode.Age := 22;
FirstNode.Link := CurrentNode;
CurrentNode := FirstNode;
New(FirstNode);
FirstNode.Name := '趙一';
FirstNode.Age := 11;
FirstNode.Link := CurrentNode;
CurrentNode := FirstNode;
Button1.Caption := '遍歷鏈表';
Button2.Caption := '插入節點';
Button3.Caption := '刪除節點';
Button4.Caption := '刪除鏈表';
Memo1.Align := alLeft;
Memo1.ScrollBars := ssVertical;
end;
{遍歷鏈表節點}
procedure TForm1.Button1Click(Sender: TObject);
begin
Memo1.Clear;
CurrentNode := FirstNode;
while Assigned(CurrentNode)
do
begin
Memo1.Lines.Add(CurrentNode.Name +
#9 + IntToStr(CurrentNode.Age));
CurrentNode := CurrentNode.Link;
end;
end;
{插入節點}
procedure TForm1.Button2Click(Sender: TObject);
var
NewNode: PMyRec;
begin
{譬如是插入在第二個節點後面}
CurrentNode := FirstNode.Link;
New(NewNode);
NewNode.Name := 'AAA';
NewNode.Age := 100;
{前後連起來}
NewNode.Link := CurrentNode.Link;
CurrentNode.Link := NewNode;
{調用遍歷}
Button1.Click;
end;
{刪除節點}
procedure TForm1.Button3Click(Sender: TObject);
begin
{譬如是刪除第二個節點}
CurrentNode := FirstNode.Link; {讓 CurrentNode 指向第二個節點}
if Assigned(CurrentNode.Link)
then
{如果 CurrentNode 還有下一個}
begin
FirstNode.Link := CurrentNode.Link;
{不能斷了鏈}
Dispose(CurrentNode); {釋放用 New 申請的內存}
end;
Button1.Click;
end;
{銷燬鏈表, 釋放所有節點}
procedure TForm1.Button4Click(Sender: TObject);
begin
CurrentNode := FirstNode; {從鏈頭向下刪除}
while Assigned(FirstNode)
do
begin
CurrentNode := FirstNode;
FirstNode := CurrentNode.Link;
Dispose(CurrentNode);
end;
Button1.Click;
end;
3.雙向鏈表
type
PMyRec = ^MyRec;
MyRec = record
Name: string[8];
Age : Word;
Prev,Next: PMyRec; {上一個與下一個的結構指針}
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
