C#以另一种方式对数字进行分组

int num = 123456789;
string numStr = num.ToString();
int[] groups = new int[numStr.Length / 2];
for (int i = 0; i < numStr.Length; i += 2)
{
    groups[i / 2] = int.Parse(numStr.Substring(i, 2));
}

int num = 123456789;
int[] groups = new int[num / 100000000 + (num % 100000000 == 0 ? 0 : 1)];
for (int i = 0; i< groups.Length; i++)
{
    groups[i] = num % 100000000;
    num /= 100000000;
}

int num = 123456789;
int[] nums = num.ToString().Select(c => int.Parse(c.ToString())).ToArray();
int[] groups = nums.Where((_, i) => i % 2 == 0).Zip(nums.Where((_, i) => i % 2 == 1), (x, y) => x * 10 + y).ToArray();