public static class IntHelper
    {
        /// <summary>
        /// 转换为2进制字符串
        /// </summary>
        /// <param name="num"></param>
        /// <returns></returns>
        public static string To2Base(this int num)
        {
            return Convert.ToString(num, 2);
        }

        /// <summary>
        /// 转换为8进制字符串
        /// </summary>
        /// <param name="num"></param>
        /// <returns></returns>
        public static string To8Base(this int num)
        {
            return Convert.ToString(num, 8);
        }

        /// <summary>
        /// 转换为16进制字符串
        /// </summary>
        /// <param name="num"></param>
        /// <returns></returns>
        public static string To16Base(this int num)
        {
            return Convert.ToString(num, 16);
        }

        /// <summary>
        /// 2进制字符串转换为int
        /// </summary>
        /// <param name="numStr"></param>
        /// <returns></returns>
        public static int From2Base(this string numStr)
        {
            return Convert.ToInt32(numStr, 2);
        }

        /// <summary>
        /// 8进制字符串转换为int
        /// </summary>
        /// <param name="numStr"></param>
        /// <returns></returns>
        public static int From8Base(this string numStr)
        {
            return Convert.ToInt32(numStr, 8);
        }

        /// <summary>
        /// 16进制字符串转换为int
        /// </summary>
        /// <param name="numStr"></param>
        /// <returns></returns>
        public static int From16Base(this string numStr)
        {
            return Convert.ToInt32(numStr, 16);
        }

        /// <summary>
        /// 将自然数转换了N进制字符串
        /// </summary>
        /// <param name="number">自然数</param>
        /// <param name="xBase">N进制(2~36之间)</param>
        /// <returns>N进制字符串</returns>
        public static string ToXBase(this int number, int xBase)
        {
            if (xBase < 2 || xBase > 36)
            {
                throw new ArgumentOutOfRangeException("参数值不在2~36的范围内");
            }

            if (xBase == 10) return number.ToString();

            int n = xBase;
            int q = number;
            int r;
            string rtn = "";

            while (q >= n)
            {
                r = q % n;
                q = q / n;

                if (r < 10)
                    rtn = r.ToString() + rtn;
                else
                    rtn = Convert.ToChar(r + 55).ToString() + rtn;

            }

            if (q < 10)
            {
                rtn = q.ToString() + rtn;
            }
            else
            {
                rtn = Convert.ToChar(q + 55).ToString() + rtn;
            }

            return rtn;
        }

        /// <summary>
        /// 判断是否为素数
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static bool IsPrime(this ulong value)
        {
            //质数(素数)定义为在大于1的自然数中
            if (value > 1)
            {
                //除了2的偶数都是合数
                if (value.IsEvenNumber())
                {
                    //2是特殊的素数
                    return value =http://www.mamicode.com/= 2;
                }

                for (ulong i = 3; (i * i) <= value; i += 2)
                {
                    if ((value % i) == 0)
                    {
                        return false;
                    }
                }

                return value != 1;
            }

            return false;
        }

        /// <summary>
        /// 是否是偶数
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static bool IsEvenNumber(this long value)
        {
            if (value < 0)
            {
                value = value * -1;
            }

            //value & 1==0则必为偶数
            return (value & 1) == 0;
        }

        /// <summary>
        /// 是否是偶数
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static bool IsEvenNumber(this ulong value)
        {
            //value & 1==0则必为偶数
            return (value & 1) == 0;
        }

        /// <summary>
        /// 是否是奇数
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static bool IsOddNumber(this ulong value)
        {
            //value & 1==0则必为偶数
            return (value & 1) > 0;
        }
    }