The Nine

implementation

{$R *.dfm}

type
PMyRec = ^MyRec;
MyRec = record
    Name: string[8];
    Age : Word;
    Link: PMyRec;
end;

var
CurrentNode, FirstNode: PMyRec;

{建立链表}
procedure TForm1.FormCreate(Sender: TObject);
begin
New(FirstNode);
FirstNode.Name := 'thenine4';
FirstNode.Age := 44;
FirstNode.Link := nil;
CurrentNode := FirstNode;

New(FirstNode);
FirstNode.Name := 'thenine3';
FirstNode.Age := 33;
FirstNode.Link := CurrentNode;
CurrentNode := FirstNode;

New(FirstNode);
FirstNode.Name := 'thenine2';
FirstNode.Age := 22;
FirstNode.Link := CurrentNode;
CurrentNode := FirstNode;

New(FirstNode);
FirstNode.Name := 'thenine1';
FirstNode.Age := 11;
FirstNode.Link := CurrentNode;
CurrentNode := FirstNode;

Button1.Caption := '遍历链表';
Button2.Caption := '插入节点';
Button3.Caption := '删除节点';
Button4.Caption := '删除链表';

Memo1.Align := alLeft;
Memo1.ScrollBars := ssVertical;
end;

{遍历链表节点}
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;

{插入节点}
procedure TForm1.Button2Click(Sender: TObject);
var
NewNode: PMyRec;
begin
{譬如是插入在第二个节点后面}
CurrentNode := FirstNode.Link;
New(NewNode);
NewNode.Name := 'AAA';
NewNode.Age := 100;

{前后连起来}
NewNode.Link := CurrentNode.Link;
CurrentNode.Link := NewNode;

{调用遍历}
Button1.Click;
end;

{删除节点}
procedure TForm1.Button3Click(Sender: TObject);
begin
{譬如是删除第二个节点}
CurrentNode := FirstNode.Link;        {让 CurrentNode 指向第二个节点}
if Assigned(CurrentNode.Link) then    {如果 CurrentNode 还有下一个}
begin
    FirstNode.Link := CurrentNode.Link; {不能断了链}
    Dispose(CurrentNode);               {释放用 New 申请的内存}
end;

Button1.Click;
end;

{销毁链表, 释放所有节点}
procedure TForm1.Button4Click(Sender: TObject);
begin
CurrentNode := FirstNode;     {从链头向下删除}
while Assigned(FirstNode) do
begin
    CurrentNode := FirstNode;
    FirstNode := CurrentNode.Link;
    Dispose(CurrentNode);
end;

Button1.Click;
end;