C++ :: Error / Expression Must Have A Class Type

I'm trying to learn recursion, and I'm using a simple array to experiment with it, but I have a couple of annoying errors that I don't understand why they're there. Here's the code:

Code:
#include <cstdlib>
#include <iostream>
using namespace std;
int largest(const int arr[], int lowerIndex, int upperIndex) {
int max;

[code]....

Now try to print the array backwards:

//Use a recursive algorithm to find the largest element in arr:
int largest(arr[], lowerIndex, upperIndex);//error: expected an expression
return 0;
}