C# convert DataTable object to XML string

        /// <summary>
        /// Convert DataTable object to XML string
        /// </summary>
        /// <param name="dt">DataTable object</param>
        /// <returns>XML string </returns>
        public static string GetXmlByDataTable(DataTable dt)
        {
            if (dt != null)
            {
                MemoryStream ms = null;
                XmlTextWriter XmlWt = null;
                try
                {
                    ms = new MemoryStream();
                    //Instantiate XmlWt according to ms
                    XmlWt = new XmlTextWriter(ms, Encoding.Unicode);
                    //Get the data in ds
                    dt.WriteXml(XmlWt);
                    int count = (int)ms.Length;
                    byte[] temp = new byte[count];
                    ms.Seek(0, SeekOrigin.Begin);
                    ms.Read(temp, 0, count);
                    //返回Unicode编码的文本
                    UnicodeEncoding ucode = new UnicodeEncoding();
                    string returnValue = ucode.GetString(temp).Trim();
                    return returnValue;
                }
                catch (System.Exception ex)
                {
                    throw ex;
                }
                finally
                {
                    //释放资源
                    if (XmlWt != null)
                    {
                        XmlWt.Close();
                        ms.Close();
                        ms.Dispose();
                    }
                }
            }
            else
            {
                return "";
            }
        }