procedure SaveStrToFile(SrcStr: string; FileName: string);
var
  FS: TFileStream;
begin
  FS := TFileStream.Create(FileName, fmCreate);
  try
    FS.WriteBuffer(SrcStr[1], Length(SrcStr) * SizeOf(SrcStr[1]));
  finally
    FS.Free;
  end;
end;

function LoadStrFromFile(FileName: string): string;
var
  FS: TFileStream;
begin
  FS := TFileStream.Create(FileName, fmOpenRead);
  try
    SetLength(Result, FS.Size div SizeOf(Result[1]));
    FS.ReadBuffer(Result[1], FS.Size);
  finally
    FS.Free;
  end;
end;

procedure SaveStrToFile(SrcStr: string; FileName: string);
var
  Stream: TStringStream;
begin
  Stream := TStringStream.Create(SrcStr, TEncoding.Unicode);
  try
    Stream.SaveToFile(FileName);
  finally
    Stream.Free;
  end;
end;
 
function LoadStrFromFile(FileName: string): string;
var
  Stream: TStringStream;
begin
  Stream := TStringStream.Create('', TEncoding.Unicode);
  try
    Stream.LoadFromFile(FileName);
    Stream.Position := 0;
    Result := Stream.ReadString(Stream.Size);
  finally
    Stream.Free;
  end;
end;