asp.net截取字符串

1，把代码放在sqlhelper中。

  #region 截取字符串
        /// <summary>
        /// 截取字符串
        /// </summary>
        /// <param name="str_value"></param>
        /// <param name="str_len"></param>
        /// <returns></returns>
        public static string leftx(string str_value, int str_len)
        {
            int p_num = 0;
            int i;
            string New_Str_value = "";

            if (str_value == "")
            {
                New_Str_value = "";
            }
            else
            {
                int Len_Num = str_value.Length;
                for (i = 0; i <= Len_Num - 1; i++)
                {
                    if (i > Len_Num) break;
                    char c = Convert.ToChar(str_value.Substring(i, 1));
                    if (((int)c > 255) || ((int)c < 0))
                        p_num = p_num + 2;
                    else
                        p_num = p_num + 1;

                    if (p_num >= str_len)
                    {
                        New_Str_value = str_value.Substring(0, i + 1);
                        break;
                    }
                    else
                    {
                        New_Str_value = str_value;
                    }

                }

            }
            return New_Str_value;
        }
        #endregion

2，前台调用：

<%# UserInfo.DAL.SqlHelper.leftx(DataBinder.Eval(Container.DataItem,"Title").ToString(),20) %>