C语言数组特性-取下标运算中的交换律----i[a] == a[i]

After the declaration and defination：
int a[] = {1,  2, 3,  4,  5 };
a + i equals i + a, they are pointers with the same value pointed to the array element a[i],
so a[i] = i[a]，(0 <= i < 5)。

#include <stdio.h>
#include <stdlib.h>

int main(void){
   int a[] = {1, 2, 3, 4, 5};

   printf("After the declaration and defination int a[] = /{1, 2, 3, 4, 5/}/n");
   printf("a[1] = %d/n", a[1]);
   printf("1[a] = %d/n", 1[a]);
}

The output is :
After the declaration and defination int a[] = {1, 2, 3, 4, 5}
a[1] = 2
1[a] = 2