delphi 压缩流问题

Question

把Memo1中的内容压缩后，在memo2中显示出来压缩的结果，为什么是空的?
主要就是得到的结果流的size为什么一直是0???
procedure TForm1.Button1Click(Sender: TObject);
var
  des_cStream:TMemoryStream;
  cStream:TCompressionStream;
  sourStream:TMemoryStream;
begin
  des_cStream:=TMemoryStream.Create;
  cStream:=TCompressionStream.Create(clMax,des_cStream);
  sourStream:=TMemoryStream.Create;
  Memo1.Lines.SaveToStream(sourStream);
  sourStream.SaveToStream(cStream);
  Memo2.Lines.LoadFromStream(des_cStream);
end;

Answer 1

memo使用的是字符串，字符串就是以NULL(#0)为结束符，而压缩数据是二进制，并不排除首字节就是#0，或者不可打印字符。

Answer 2

uses
  zlib;//压缩测试
procedure TForm2.Button1Click(Sender: TObject);
var
    des_cStream:TMemoryStream;
    cStream:TCompressionStream;
    sourStream:TMemoryStream;
begin
    des_cStream:=TMemoryStream.Create;
    cStream:=TCompressionStream.Create(clMax,des_cStream);
    sourStream:=TMemoryStream.Create;
    Memo1.Lines.SaveToStream(sourStream);
    sourStream.SaveToStream(cStream);
    cStream.Free;
    sourStream.Free;
    Memo2.Lines.LoadFromStream(des_cStream);
    des_cStream.SaveToFile('c:\aa.bin');
    des_cStream.Free;
end;//解压缩测试
procedure TForm2.Button2Click(Sender: TObject);
var
    des_cStream:TMemoryStream; 
    cStream:TDeCompressionStream;
    sourStream:TMemoryStream;
begin
    if Not FileExists('c:\aa.bin') then
      Button1.Click;
    if Not FileExists('c:\aa.bin') then Exit;
    des_cStream:=TMemoryStream.Create;    sourStream:=TMemoryStream.Create;
    des_cStream.LoadFromFile('c:\aa.bin');
    des_cStream.Position := 0;
    cStream:=TDeCompressionStream.Create(des_cStream);
    sourStream.Size := des_cStream.Size;
    cStream.Read(sourStream.Memory^,des_cStream.Size);
    cStream.Free;
    des_cStream.Free;
    sourStream.Position := 0;
    Memo2.Lines.LoadFromStream(sourStream);
    sourStream.SaveToFile('c:\bb.bin');
    sourStream.Free;
end;