C# XML转义字符的转换

在XML中需要插入自己的字符串，但是发现&<>"这些字符无法替换掉，使用正常的Replace没有效果，网上也没有找到合适的。并且由于是控制台程序，无法引用NET类，经过查询MSDN得到些启发，写下这个转换方法，以供参考。如果有更好的方法可以共享下！ 

       #region XML转义字符处理
        /// <summary>
        /// XML转义字符处理
        /// </summary>
        public static string ConvertXml(string xml)
        {

            xml = (char)1 + xml;   //为了避免首字母为要替换的字符，前加前缀

            for (int intNext = 0; true; )
            {
                int intIndexOf = xml.IndexOf("&", intNext);
                intNext = intIndexOf + 1;  //避免&被重复替换
                if (intIndexOf <= 0)
                {
                    break;
                }
                else
                {
                    xml = xml.Substring(0, intIndexOf) + "&amp;" + xml.Substring(intIndexOf + 1);
                }
            }

            for (; true; )
            {
                int intIndexOf = xml.IndexOf("<");
                if (intIndexOf <= 0)
                {
                    break;
                }
                else
                {
                    xml = xml.Substring(0, intIndexOf) + "&lt;" + xml.Substring(intIndexOf + 1);
                }
            }

            for (; true; )
            {
                int intIndexOf = xml.IndexOf(">");
                if (intIndexOf <= 0)
                {
                    break;
                }
                else
                {
                    xml = xml.Substring(0, intIndexOf) + "&gt;" + xml.Substring(intIndexOf + 1);
                }
            }

            for (; true; )
            {
                int intIndexOf = xml.IndexOf("\"");
                if (intIndexOf <= 0)
                {
                    break;
                }
                else
                {
                    xml = xml.Substring(0, intIndexOf) + "&quot;" + xml.Substring(intIndexOf + 1);
                }
            }

            return xml.Replace(((char)1).ToString(), "");

        }
        #endregion