dynamicarrayexamplespas.pas

文本编辑程序

unit DynamicArrayExamplespas;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    ListBox1: TListBox;
    Label1: TLabel;
    Label2: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure ListBox1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
    procedure FreeThem;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  p: TPointerArray;
  l: TLongArray;
//Byte arrays are also available   TByteArray
implementation

{$R *.DFM}

procedure TForm1.FormCreate(Sender: TObject);
begin

  // Create the dynamic arrays
  P := TPointerArray.Create( nil );
  L := TLongArray.Create(nil);

end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin

  //Free the buttons
  FreeThem;
  //Free the arrays. They will automaticly empty themselves
  P.Free;
  L.Free;

end;

procedure TForm1.FreeThem;
var
  lngIndex: LongInt;
begin

  //This will empty the buttons pointer array
  while p.UBound > 0 do begin
    lngIndex := p.UBound;
    TButton( P.GetElement(lngIndex) ).Free;
    p.RedimPreserve(lngIndex - 1);
  end;
  p.FreeArray;

end;

procedure TForm1.Button1Click(Sender: TObject);
var
  lngIndex: LongInt;
  B: TButton;
begin

//Add an element to the array
  lngIndex := p.UBound;
  p.RedimPreserve( lngIndex + 1 );
//Create a new button
  B := TButton.Create(Form1);
  B.Parent := Form1;
  B.Height := 20;
  B.Width := 20;
  B.Left := lngIndex * B.Width;
  B.Top := 0;
  B.Caption := IntToStr( lngIndex );
  B.OnClick := Button1Click;
//Point the new array element to the new button
  p.SetElement( lngIndex, B );

end;

procedure TForm1.ListBox1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var
  lngIndex: LongInt;
begin

//Add a new array element
  lngIndex := l.UBound + 1;
  l.RedimPreserve( lngIndex );

//Assign a value to the new element
//This
  l.SetElement( lngIndex, lngIndex );
//or
  CopyMemory( l.AddrElement(lngIndex), @lngIndex, 4 );
//do the same thing

//Empty it once it gets to big. Just for the fun of it
  if l.UBound = 21 then L.FreeArray;

//Display array inside the list box
  ListBox1.Clear;
  for lngIndex := 0 to l.UBound do
    ListBox1.Items.Add( IntToStr( l.GetElement(lngIndex) ) );

end;

end.