Even Odd problem

#include <iostream>
#include <vector>
using namespace std;


void evenOdd(vector<int> &v) {
    int next_even = 0;
    int next_odd = v.size() - 1;
    while (next_even < next_odd) {
        if (v[next_even] % 2 == 1) {
            swap(v[next_even], v[next_odd--]);
        }
        else {
            next_even++;
        }
    }
}

int main()
{
    vector<int> v = { 1, 2, 3 , 4, 5, 6, 7};
    evenOdd(v);
    for (auto i = v.begin(); i != v.end(); i++)
        cout << *i << " ";
    return 0;
}