Question

Is it a good idea to process two-dimensional arrays using pointers?

for( p = &a[0][0]; p < &a[N][N]; p++){
    *p = 0;
}

Or is it better to use indexing?

Answer 1

The way you have denoted your array doesn’t guarantee that pointer arithmetic will always work. Given how you’ve declared your two-dimensional array, it is probably not an issue, but it is certainly not good style.

However, imagine instead the array is allocated dynamically. Something like this:

int **p = malloc(ARR_SIZE * sizeof(*p));
for (i = 0; i < ARR_SIZE; i++) {
    p[i] = malloc(ARR_SIZE * sizeof(**p));
}

This is a two-dimensional array (of sorts), but will not guarantee that allocated memory will be contiguous and hence would break your loop.