Output question pointers

Question

int arr[3]={40,41,42};
int *ptr=(int*)(&arr+1);
printf("%d %d", *(arr+1), *(ptr-1));
Why is the answer 41,42?

Answer 1

Writing *(arr+i) is same as writing arr[i].
So *(arr+1) = arr[1] = 41. (1st answer)
(Since in C array index starts from 0.)

&arr is address of the whole array arr[].
When we add 1 to &arr, we get base address of arr[] + sizeof(arr). And then this value is typecasted to int *.
So ptr points to the memory just after 42 is stored.
Then you're type-casting ptr to int * and printing the value of *(ptr-1).
Since ptr points memory after 42, ptr - 1 points to 42. (2nd answer)