Array Help

I know arrays are easy and everything.. but something which I think should be perfectly logical isn't working in my program.

I'm trying to make a method to reverse the order of my array, so that, for example
1 2 3 4 5
will become
5 4 3 2 1

I use something basic:
int left=array[0];
    int right=array.length;
    while(left<right){
        int temp=array[left];
        array[left]=array[right];
        array[right]=temp;
        left++;
        right--;

But array.length isn't number at the end of the array, it's the size of the array! If I have:

int num[] = new int[10] where num[10]=23, then num.length will return 10, not 23.

So I've tried using something like num[num.length], but I keep getting an error message about something being out of bounds. What am I doing wrong?

In b4 pointless java flames.


(define (last list)
 (if (null? (cdr list))
  (car list)
  (last (cdr list))))

(define (butlast list)
 (if (null? (cdr list))
 '()
  (cons (car list) (butlast (cdr list)))))

(define (reverse list)
 (if (null? list)
 '()
  (cons (last list) (reverse (butlast list)))))