queue.s.r = clone(queue.s.r)
This function is used as a constructor to create a copy of a
pre-existing instance of the Queue class. The new instance will
be identical to the original instance in all respects, except
that it will use different storage - therefore operations on the
original instance will not affect the new instance, and vice-versa.
queue a pointer to the queue (structure of type Queue)
This function returns:
a pointer to the newly-created instance of the Queue class upon
success, or a null pointer upon failure to allocate virtual memory.
Use of this class requires the following header files:
create_Queue() the constructor for instances of the Queue class
queue_2 = (*queue_1->clone)(queue_1);