int bla(int x, int &y)
{
  x = x+y;
  y = 1;
  return y;
}

...

   int a,b,c;
   a = 2;
   b = 3;
   c = bla(a,b);
// here
...
Answers: a = 2, b = 1, c = 1

int blup(int &x, int &y)
{
   x = 4;
   return 5;
   y = 6;
}
...
   int d,e,f;
   d = 7;
   e = 8;
   f = blup(d,e);
// here
Answers: d = 4, e = 8, f = 5