/// <summary>
        /// 截取字符串并去掉图片
        /// </summary>
        /// <param name="content">要处理的字符串</param>
        /// <param name="length">截取长度</param>
        /// <param name="tail">尾部特定字符</param>
        /// <returns></returns>
        public static string CutWithoutPic(string content, int length, string tail)
        {
            int conlength = content.Length;
            int begin = 0;
            int end = 0;
            int endcharlen = 3;
            string result = "";
            begin = content.ToLower().IndexOf("<img ", 0);
            if (begin == -1)
            {
                begin = content.ToLower().IndexOf("<input type=\"image", 0);
                if (begin != -1)
                {
                    end = content.ToLower().IndexOf("/>", begin);
                    if (end == -1)
                    {
                        end = content.ToLower().IndexOf(">", begin);
                        endcharlen = 2;
                    }
                    if (end == -1)
                        end = content.ToLower().IndexOf("/ >", begin);
                    result += content.Substring(0, begin);
                    result += content.Substring(end + endcharlen);
                }
            }
            result = content;
            return CutString(result, length, tail);
        }
/// <summary>
        /// 按长度截取字符串并在尾部添加特定字符
        /// </summary>
        /// <param name="str">原字符串</param>
        /// <param name="length">截取长度</param>
        /// <param name="tail">尾部特定字符</param>
        /// <returns>返回截取后含有尾部的字符串</returns>
        public static string CutString(string str, int length, string tail)
        {
            if (string.IsNullOrEmpty(tail))
                tail = "...";
            if (str.Length < length)
                return str;
            else
                return str.Substring(0, length) + tail;
        }