Write void reverseArray(int* arr, int size) using two pointers. Start one at the beginning and one at the end, then swap elements and move the pointers toward the center until they meet.
You'll need: int* left = arr; int* right = arr + size - 1;. Then while(left < right), swap *left and *right, then left++ and right--. This works without any array indexing. Test with arrays of different sizes including odd and even lengths.
This problem combines pointer arithmetic, dereferencing, and comparison. It's a classic algorithm that shows pointer strengths.