Enumerator yield

gistfile1.cs

static IEnumerable<int> Fibs (int fibCount)
{
  for (int i = 0, prevFib = 1, curFib = 1; i < fibCount; i++)
  {
    yield return prevFib;
    int newFib = prevFib+curFib;
    prevFib = curFib;
    curFib = newFib;
  }
}
/*
 On each  yield statement, control is re-turned to the caller, but the 
 callee’s state is maintained so that the method can
 continue executing as soon as the caller enumerates the next element.
 
 A return  statement is illegal in an iterator block—you must use
a yield breakinstead.
*/