//字符串截取方法

        //字符串截取方法
        string SubStr(string str, int count)
        {

            int n = count * 2;
            string temp = string.Empty;
            if (System.Text.Encoding.Default.GetByteCount(str) <= n)//如果長度比需要的長度n小,返回原字符串
            {
                return str;
            }
            else
            {
                int t = 0;
                char[] q = str.ToCharArray();
                for (int i = 0; i < q.Length; i++)
                {
                    if ((int)q[i] >= 0x4E00 && (int)q[i] <= 0x9FA5)//是否漢字
                    {
                        temp += q[i];
                        t += 2;
                    }
                    else
                    {
                        temp += q[i];
                        t += 1;
                    }
                    if (t >= n)
                    {
                        break;
                    }
                }
                return (temp + "...");
            }
        }