System.Net.FtpControlStream.TryUpdateContentLength C# (CSharp) Method

        private void TryUpdateContentLength(string str)
        {
            int pos1 = str.LastIndexOf("(");
            if (pos1 != -1)
            {
                int pos2 = str.IndexOf(" bytes).");
                if (pos2 != -1 && pos2 > pos1)
                {
                    pos1++;
                    long result;
                    if (Int64.TryParse(str.Substring(pos1, pos2 - pos1),
                                        NumberStyles.AllowLeadingWhite | NumberStyles.AllowTrailingWhite,
                                        NumberFormatInfo.InvariantInfo, out result))
                    {
                        _contentLength = result;
                    }
                }
            }
        }