一天一个离职小技巧之数组负下标

int array[11] = {0, 1, 2,
                 3, 4, 5,
                 6, 7, 8,
                 9, 10};

int *a = &array[5];    // 指针向前偏移5位
printf("%d\n", a[-5]); // => 0
printf("%d\n", a[0]);  // => 5
printf("%d\n", a[5]);  // => 10

int *a = &array[5];
=>
int *a = (array + 5);

a[-5]
=>
*(a - 5)
=>
*((array + 5) - 5)
=>
*(array + 0)
=>
array[0]

a[0]
=>
array[0 + 5]
=>
array[5]

a[5]
=>
array[5 + 5]
=>
array[10]