//宣告一個數組
            int[] num =new int[3]{4,6,2};
            int a = num.Length;//得到陣列的長度
            for (int i = 0; i < a; i++)
            {
                Console.WriteLine(num[i]);
            }
            int j=0;
            while(j<a){
                Console.WriteLine(num[j]);
                j++;
            }
            foreach (int temp in num)
            {
                Console.WriteLine(temp);
            }