/// <summary>

        /// 截取中英混合字符串指定长度

        /// </summary>

        /// <param name="str">中英混合的字符串</param>

        /// <param name="length">长度</param>

        /// <returns></returns>

        public static string GetStringByLength(string str, int length)

        {

            string temp = str;

            int j = 0;

            int k = 0;

            for (int i = 0; i < temp.Length; i++)

            {

                if (Regex.IsMatch(temp.Substring(i, 1), @"[\u4e00-\u9fa5]+"))

                {

                    j += 2;

                }

                else

                {

                    j += 1;

                }

                if (j <= length)

                {

                    k += 1;

                }

                if (j >= length)

                {

                    return temp.Substring(0, k);

                }

            }

            return temp;

        }