//passage des variables par referance
#include <iostream>

using namespace std;

//passage par reference
void swap(int &n1, int &n2);

int main() {
  int n1 = 10;
  int n2 = 20;
  cout << "avant swap : " << n1 << " " << n2 << endl;
  swap(n1, n2);
  cout << "apres swap : " << n1 << " " << n2 << endl;

  return 0;
}

void swap(int &n1, int &n2) {
  int temp = n1;
  n1 = n2;
  n2 = temp;
  cout << "dans swap : " << n1 << " " << n2 << endl;
}