As long as you make sure the end points are valid, this is most intuitive for me.
Just using i as a backwards step.
for (int i = 1; i <= N; i++) {
array[N-i]
}This fails on overflow: if N == INT_MAX then your loop doesn't terminate and actually invokes undefined behavior in C.
The safe way to write it is:
for (int i = 0; i < N; ++i) {
something(array[N - 1 - i]);
}