C# 已排序好的数组中查找数的位置

        static int FindNumber(int[] array, int num)
        {
            int result = -1;
            if (array == null)
            {
                return result;
            }

            for (int i = 0; i < array.Length - 1; i++)
            {
                if (array[i] > array[i + 1])
                {
                    throw new Exception("input array is not sorted properly.");
                }
            }

            for (int j = 0; j < array.Length; j++)
            {
                if (array[j] == num)
                {
                    result = j;
                }
            }
            return result;
        }

        static int FindNumber1(int[] array, int num)
        {
            int result = -1;
            if (array == null)
            {
                return result;
            }
            for (int i = 0; i < array.Length -1; i++)
            {
                if (array[i] > array[i +1])
                {
                    throw new Exception("input array is not softed properly.");
                }
            }

            int low = 0;
            int mid = 0;
            int high = array.Length - 1;

            while (low<=high)
            {
                mid = (low + high) / 2;
                if (array[mid] == num)
                {
                    result = mid;
                    break;
                }
                if (array[mid] < num)
                {
                    low = mid + 1;
                }
                else
                {
                    high = mid - 1;
                }
            }
            return result;
        }

测试用例

{1,2,3,4}, 3

{1,2,3,4}, 5

{1,2,3,4}, 1

{1,2,3,4}, 4

{2,1,3,4}, 3

{2,1,3,4}, 0

null , 1

{}, 1

{1,2,3........999...} ,  323