insertion sort - array

#include <iostream>
#include <array>
#define N 5

using namespace std;

void swap (int& a, int& b)
{
    int aux = a;
    a = b;
    b = aux;
}

void printarray (array<int,N>& a)
{
    for (int i=0; i<N; i++)
        cout << a.at(i) << " ";
    cout << "\n";
}

void insertion_sort (array<int,N>& a)
{
    for (int i=1; i<N; i++)
        for (int j=i; j>0 and a.at(j) < a.at(j-1); j--)
            swap(a.at(j),a.at(j-1));
}

int main()
{
    array<int,N> arr = {5,4,3,2,1};
    insertion_sort(arr);
    printarray(arr);

    return 0;
}