Q: Does (*a_pos += 1) == (a_pos[x + 1]), where x starts at 0
A:

    *a_pos += 1 is the same as *a_pos = *a_pos + 1.

    This increments the value at that address.  It does not increment the address itself.

    *a_pos += 1 is the same as *a_pos = (*a_pos) + 1.

    a_pos[x + 1] is the same as *(a_pos + (x + 1))

    If x were 0, then
    a_pos[x + 1] is the same as *(a_pos + (0 + 1))
                 is the same as *(a_pos + 1)


    A:  *a_pos + 1 is NOT the same as a_pos[1] due to precedence rules.