急：如何用TFileStream和Tmemorystream读写流

Question

我先用Tfilestream从xx.xml文件读出数据，然后赋给buffer,再从buffer赋给Tmemorystream,就会出错“Stream write error”是什么原因？
代码如下：
procedure TForm1.Button2Click(Sender: TObject);
var
    stream,Stream2:TStream;
    Buffer: Pointer;
    size:integer;
begin
if OpenDialog1.Execute then
begin
  stream2:=  TMemoryStream.Create;
  Stream := TFileStream.Create(OpenDialog1.FileName, fmOpenRead);
  size:=stream.Size;
  inc(size);
  getmem(buffer,size);
  stream.writebuffer(Buffer^,Size);
  stream2.readbuffer(Buffer^,size);
  cds.LoadFromStream(stream2);
end;
end;

Answer 1

procedure TForm1.Button2Click(Sender: TObject);
var
    stream,Stream2:TStream;
    Buffer: Pointer;
    size:integer;
begin
if OpenDialog1.Execute then
begin
  stream2:=  TMemoryStream.Create;
  Stream := TFileStream.Create(OpenDialog1.FileName, fmOpenRead);
  size:=stream.Size;
  inc(size);
  getmem(buffer,size);
  stream.Position := 0;
  stream.ReadBuffer(Buffer^,Size);
  stream2.Position := 0;
  stream2.WriteBuffer(Buffer^,size);
  cds.LoadFromStream(stream2);
end;
end;

Answer 2

stream2.readbuffer(Buffer^,size);
  stream2.Position := 0; //加這句試下
  cds.LoadFromStream(stream2);

Answer 3

问题解决,我试过了用stream2.seek(0,sofrombeginning);也可以等效于stream2.Position := 0