C++ :: Returning The Number Of Elements In A List

I am given an array with n elements but need to write a function where it returns n-1 elements. Do I need a loop for this? Or must I write a prototype...

Here is what I have thus far:

//given array with 5 elements function must return value 4 elements since -1 is a special character length of list is finite

#include <iostream>
using namespace std;
int main () {
int array [] = {1, 4, -1, 3, 2};
cout << "The array has " <<sizeof (array)/ sizeof (int)<< " elements"<< endl;
return 0;
}