Delphi 2009 泛型容器单元(Generics.Collections)[3]: TStack<T>

跟着万一老师学习笔记

TQueue 和 TStack, 一个是队列列表, 一个是堆栈列表; 一个是先进先出, 一个是先进后出.

TStack 主要有三个方法、一个属性:
Push(压栈)、Pop(出栈)、Peek(查看下一个要出栈的元素);
Count(元素总数).

-------------------------------------------------------------------------------------------------------------------------------------------------------------------

 -------------------------------------------------------------------------------------------------------------------------------------------------------------------

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
  Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses
  System.Generics.Collections;

type
  TRec = record
    Name: string;
    Age: Integer;
  end;

var
  Stack: TStack<TRec>;
{压栈 PUSH}

procedure TForm1.Button1Click(Sender: TObject);
var
  rec: TRec;
begin
  rec.Name := StringOfChar(Char(65 + Random(26)), 3);
  rec.Age := Random(250);
  Stack.Push(rec);
  Text := Format('当前队列成员总数: %d', [Stack.Count]);
  {让 Memo1 配合显示}
  Memo1.Lines.Add(Format('%s, %d', [rec.Name, rec.Age]));
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  rec: TRec;
begin
  if Stack.Count = 0 then
    exit;
  rec := Stack.Pop;
  ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
  Text := Format('当前队列成员总数: %d', [Stack.Count]);

  {让 Memo1 配合显示}
  Memo1.Lines.Delete(Memo1.Lines.Count - 1);
end;

 {下一个出列的的元素: Peek}
procedure TForm1.Button3Click(Sender: TObject);
var
  rec: TRec;
begin
  if Stack.Count = 0 then
    exit;
  rec := Stack.Peek;
  ShowMessage(Format('%s, %d', [rec.Name, rec.Age]));
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Stack := TStack<Trec>.Create;
  Memo1.Clear;
  Button1.Caption := Button1.Caption + ' 压栈';
  Button2.Caption := Button2.Caption + ' 出栈';
  Button3.Caption := Button3.Caption + ' 下一个出栈的...';
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  Stack.Free;
end;

end.