public void GetAllSegments( 
   ref ICollection<Segment> segments
)

{
  ICollection<Segment> collectionSegments = new List<Segment>();
  polyline.GetAllSegments(ref collectionSegments);
  int numSegmentsInCollection = collectionSegments.Count;    // = 10

  IList<Segment> iList = collectionSegments as IList<Segment>;
  for (int i = 0; i < numSegmentsInCollection; i++)
  {
    // do something with iList[i]
  }

  // use the segments to build another polyline
  Polyline polylineFromSegments = PolylineBuilderEx.CreatePolyline(collectionSegments);
}

{
  List<Segment> segmentList = new List<Segment>(30);
  ICollection<Segment> collection = segmentList;
  polygon.GetAllSegments(ref collection);
  // segmentList.Count = 4
  // segmentList.Capacity = 30

  // use the segments to build another polygon
  Polygon polygonFromSegments = PolygonBuilderEx.CreatePolygon(collection);
}