学步园

 #region 求以下表达式的值，写出您想到的一种或几种实现方法： 1-2+3-4+……+m
        /// <summary>
        ///
        /// </summary>
        /// <param name="m"></param>
        public static void GetNum(int m)
        {
            int sum = 0;
            bool flag = true;
            for (int i = 1; i <= m; i++)
            {
                if (flag)
                    sum += i;
                else
                    sum -= i;
                flag = !flag;
            }
            //return sum;
            Console.WriteLine(sum.ToString());
        }
        #endregion