unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

//Integer 与 PInteger
procedure TForm1.Button1Click(Sender: TObject);
var
  int: Integer;
  pint: PInteger; {定义类型指针, Integer 类型的指针}
begin
  int := 100;
  pint := @int;        {现在 pint 就是 int 的指针}
  pint^ := pint^ + 1;  {现在 pint^ 和 int 是一回事, 测试一下:}
  ShowMessage(IntToStr(int));   {101}
  ShowMessage(IntToStr(pint^)); {101}
end;

//直接定义类型指针
procedure TForm1.Button2Click(Sender: TObject);
var
  int: Integer;
  PMyInt: ^Integer;
begin
  int := 100;
  PMyInt := Addr(int); {这句和: PMyInt := @int; 相同}
  PMyInt^ := PMyInt^ + 1;
  ShowMessage(IntToStr(int));     {101}
  ShowMessage(IntToStr(PMyInt^)); {101}
end;

//先自定义指针类型
procedure TForm1.Button3Click(Sender: TObject);
type
  PInt = ^Integer;
var
  int: Integer;
  PMyInt: PInt;
begin
  int := 100;
  PMyInt := @int;
  PMyInt^ := PMyInt^ + 1;
  ShowMessage(IntToStr(int));     {101}
  ShowMessage(IntToStr(PMyInt^)); {101}
end;

//指针的指针
procedure TForm1.Button4Click(Sender: TObject);
var
  int: Integer;
  pint: PInteger;
  ppint: ^PInteger;
begin
  int := 100;
  pint := @int;
  ppint := @pint;
  ppint^^ := ppint^^ + 1;
  ShowMessage(IntToStr(int));     {101}
  ShowMessage(IntToStr(pint^));   {101}
  ShowMessage(IntToStr(ppint^^)); {101}
end;

end.