无法反转阵列

Question

所以我有这个程序应该采用一个数组并按相反的顺序排列，并给出所述数字的平均值。输入负数时，程序终止。我非常接近完成它但目前我无法获得相反的方面。感谢帮助！

#include <iostream>
using namespace std;
int main(){
    //Written By: Hannah Stang
    //Reads a series of positive integers until user enters -1.
    //Prints values in reverse order and gives the average of the values
    cout << "Please enter positive integers as desired, when finished enter a negative integer to get results. ";
    int sum = 0, avg, num, numsize = 0;
    cin >> num;
    void reverse (int array[] );
    while (num >= 0)
    {
        numsize = numsize + 1;
        sum = sum + num;
        cin >> num;
        avg = sum / numsize;
    }
    cout << "The values in reverse order are " << endl;
    cout << "The average is " << avg << endl;
}