Create virtual files in asp

    private void virfile()
    {
        if (!Directory.Exists(Server.MapPath("download/")))
            Directory.CreateDirectory(Server.MapPath("download/"));
        string filpath = Server.MapPath("download/" + "data.txt");
        string filedir = filpath.Substring(0, filpath.LastIndexOf('.'));
        string fileext = System.IO.Path.GetExtension(filpath);
        if (!File.Exists(filpath))
        {
            File.AppendAllText(filpath, "file downloaded on : " + DateTime.Now.ToString() + "\r\n");
        }
        else
        {
            int i = 1;
            while (true)
            {
                filpath = filedir + "(" + i + ")" + fileext;
                if (!File.Exists(filpath))
                {
                    File.AppendAllText(filpath, "file downloaded on : " + DateTime.Now.ToString() + "\r\n");
                    break;
                }
                i++;
            }
        }
    }