小数的分数表示

小数的分数表示

/// <summary>
        /// 获取小数的分数表示
        /// </summary>
        /// <param name="decimalPart">小数不循环部分</param>
        /// <param name="loopPart">小数循环部分</param>
        /// <returns></returns>
        public static string Formula(int decimalPart,int loopPart)
        {
            int u = decimalPart * ((int)Math.Pow(10,loopPart.ToString().Length) - 1) + loopPart;
            int d = ((int)Math.Pow(10, loopPart.ToString().Length) - 1) * (int)Math.Pow(10,decimalPart==0?0:decimalPart.ToString().Length);
            
            Debug.WriteLine("up:" + u);
            Debug.WriteLine("down:" + d);
            int maxDivisor = MaxDivisor(u, d);
            Debug.WriteLine("max divisor:" + maxDivisor);
            int u1 = u / maxDivisor;
            int d1 = d / maxDivisor;
            StringBuilder sb = new StringBuilder();
            sb.Append(u1).Append("/").Append(d1);
            return sb.ToString();
        }

        /// <summary>
        /// 获取两个数的最大公约数
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static int MaxDivisor(int a, int b)
        {
            while (a != 0 && b != 0)
            {
                //获取余数（大整数时候效率很低）
                int k = a % b;
                a = b;
                b = k;
            }

            return a;
        }

        public static void TestMaxDivisor()
        {
            Console.WriteLine("result:"+Formula(5, 0)); 
        }