Arrays vs Pointers

Four pieces pinning down exactly where "arrays are just pointers" is true and where it very much isn't.

int arr[5];
int *p = arr;

printf("%zu\n", sizeof(arr));   /* 20 — the full array */
printf("%zu\n", sizeof(p));     /* 8 — just a pointer */

arr = p;    /* compile error — arr is not a modifiable value, p is */
p = arr;    /* fine — p can be reassigned to point anywhere */

Indexing (arr[i] / p[i]) and dereferencing behave identically either way — that's the part that makes them feel interchangeable. sizeof and reassignment are where they split: an array name is a fixed label for a fixed block of memory, not a variable that can be pointed elsewhere, while a pointer genuinely is just a variable holding an address.