字符串长度获取与截取

        /// <summary>
        /// 获取字符串长度
        /// </summary>
        /// <param name="str">要获取的字符串</param>
        /// <returns></returns>
        private int GetLengthFromString(string str)
        {
            int t = 0;
            char[] q = str.ToCharArray();
            for (int i = 0; i < q.Length; i++)
            {
                if ((int)q[i] >= 0x4E00 && (int)q[i] <= 0x9FA5)//是否汉字
                {
                    t += 2;
                }
                else
                {
                    t += 1;
                }
            }
            return t;
        }

        /// <summary>
        /// 根据长度截取字符串,超出部分显示省略号,汉字2个字节，字母数字一个字节
        /// </summary>
        /// <param name="str">要截取的字符串</param>
        /// <param name="n">要截取的长度</param>
        /// <returns></returns>
        private string Stringformat(string str, int n)
        {
            string temp = string.Empty;
            if (System.Text.Encoding.Default.GetByteCount(str) <= n)//如果长度比需要的长度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)//是否汉字
                    {
                        temp += q[i];
                        t += 2;
                    }
                    else
                    {
                        temp += q[i];
                        t += 1;
                    }
                    if (t >= n)
                    {
                        break;
                    }
                }
                return (temp + "...");
            }
        }