(Wide)String - storing in TFileStream, Delphi 7. What is the fastest way?

Question

I\'m using Delphi7 (non-unicode VCL), I need to store lots of WideStrings inside a TFileStream. I can\'t use TStringStream as the (wide)strings are mixed with binary data, t

Answer 1

There is nothing special about wide strings, to read and write them as fast as possible you need to read and write as much as possible in one go:

procedure TForm1.Button1Click(Sender: TObject);
var
  Str: TStream;
  W, W2: WideString;
  L: integer;
begin
  W := 'foo bar baz';

  Str := TFileStream.Create('test.bin', fmCreate);
  try
    // write WideString
    L := Length(W);
    Str.WriteBuffer(L, SizeOf(integer));
    if L > 0 then
      Str.WriteBuffer(W[1], L * SizeOf(WideChar));

    Str.Seek(0, soFromBeginning);
    // read back WideString
    Str.ReadBuffer(L, SizeOf(integer));
    if L > 0 then begin
      SetLength(W2, L);
      Str.ReadBuffer(W2[1], L * SizeOf(WideChar));
    end else
      W2 := '';
    Assert(W = W2);
  finally
    Str.Free;
  end;
end;