精確截取字符串長度

        /**//// <summary>
        /// 精確截取字符串長度

        /// </summary>
        /// <param name="str">字符串</param>
        /// <param name="length">截取的長度</param>
        /// <returns>返回截取後的字符串</returns>
        public static string CutString(string str,int length)
        ...{
            return CutString(str,length,"..");
        }

        /**//// <summary>
        /// 精確截取字符串長度

        /// </summary>
        /// <param name="str">需要截取的字符串</param>
        /// <param name="length">截取的字符串長度</param>
        /// <param name="overstr">大於截取部分表示方式</param>
        /// <returns></returns>
        public static string CutString(string str,int length,string overstr)
        ...{
            length=length*2;
            str = str.Trim();
            byte[] buffer1= Encoding.Default.GetBytes(str);
            if (buffer1.Length > length)
            ...{
                string text1 = "";
                for (int num1 = 0; num1 < str.Length; num1++)
                ...{
                    byte[] buffer2 = Encoding.Default.GetBytes(text1);
                    if (buffer2.Length >= length)
                    ...{
                        break;
                    }
                    text1 = text1 + str.Substring(num1, 1);
                }
                return (text1 +overstr);
            }
            return str;
        }