按字节截取中英文

    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                Console.WriteLine("请输入字符串：");
                string s = getInput(0);
                Console.WriteLine("请输入截取的字节长度（整数）：");
                int l = Convert.ToInt32(getInput(1));
                s = GetSubStringByByte(s, l);
                Console.WriteLine("输出的结果：" + s);
                Console.WriteLine("................................................
");
            }
        }
        static string getInput(int type)
        {
            while (true)
            {
                string s = string.Empty;
                try
                {
                    s = Console.ReadLine();
                }
                catch { }
                if (type == 0)
                {
                    if (!string.IsNullOrWhiteSpace(s))
                    {
                        return s;
                    }
                    else
                    {
                        Console.WriteLine("请输入正确的字符串：");
                    }
                }
                else
                {
                    int l = 0;
                    if (int.TryParse(s,out l))
                    {
                        return s;
                    }
                    else
                    {
                        Console.WriteLine("请输入正确的整数：");
                    }
                }
            }
        }
        /// <summary>
        /// 按字节截取字符串
        /// </summary>
        /// <param name="s">所要截取的字符串</param>
        /// <param name="l">截取字节长度</param>
        /// <param name="endStr">后接字符串（如“...”）</param>
        /// <returns></returns>
        static public string GetSubStringByByte(string s, int l, string endStr = "")
        {
            string temp = s;
            if (string.IsNullOrEmpty(temp))
            {
                return string.Empty;
            }
            else if (Regex.Replace(temp, "[u4e00-u9fa5]", "zz", RegexOptions.IgnoreCase).Length <= l)
            {
                return temp;
            }
            int j = 0, k = 0;

            CharEnumerator ce = temp.GetEnumerator();
            while (ce.MoveNext())
            {
                j += (ce.Current > 0 && ce.Current < 255) ? 1 : 2;

                if (j <= l)
                {
                    k++;
                }
                else
                {
                    temp = s.Substring(0, k);
                    break;
                }
            }
            return temp + endStr;
        }
    }