Permutations of a string

void permutation(string str, int i)
{
  int n=str.size()
  if (i == n - 1)
  {
    cout << str << endl;
    return;
  }
  for (int j = i; j < n; j++)
  {
    swap(str[i], str[j]);
    permutation(str, i + 1);
    swap(str[i], str[j]); //swap is built-in function in CPP
  }
}