public void GetAllSegments( 
   ref ICollection<Segment> segments
)

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 = PolygonBuilder.CreatePolygon(collection);

ICollection<Segment> collection = new List<Segment>();
polyline.GetAllSegments(ref collection);
int numSegments = collection.Count;    // = 10

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

// use the segments to build another polyline
Polyline polylineFromSegments = PolylineBuilder.CreatePolyline(collection);