record 的一个小问题

Delphi(Pascal) code

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, Buttons;type   TMapRec = record        X, Y: Integer;        ImageName: string[10];   end;type  TForm1 = class(TForm)    SpeedButton1: TSpeedButton;    procedure SpeedButton1Click(Sender: TObject);  private    { Private declarations }    Fs: TFileStream;    FileSize: Integer;    MapData: array of TMapRec;  public    { Public declarations }  end;var  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.SpeedButton1Click(Sender: TObject);begin  MapData[0].X := 1; //这里出错! 怎么赋值才不会出错呢?  MapData[0].Y := 1;  MapData[0].ImageName := 'T1';  MapData[1].X := 2;  MapData[1].Y := 2;  MapData[1].ImageName := 'T2';  Fs := TFileStream.Create('C:\Users\Ekmin\Desktop\1.txt', fmOpenWrite);  //Fs.WriteBuffer(FileSize, SizeOf(FileSize));  SetLength(MapData, FileSize);  Fs.WriteBuffer(MapData[0], SizeOf(TMapRec) * FileSize);  Fs.Destroy;end;end.

[解决办法]
动态数组先申请大小吧？
[解决办法]
MapData: array of TMapRec;

SetLength(MapData, 2);//这里应该设置数量
MapData[0].X := 1; //这里出错! 怎么赋值才不会出错呢?
MapData[0].Y := 1;
MapData[0].ImageName := 'T1';
MapData[1].X := 2;
MapData[1].Y := 2;
MapData[1].ImageName := 'T2';