2004 A.M. Turing Award Winners Vinton G. Cerf Robert E. Kahn Citation For pioneering work on internetworking, including the design and implementation of the Internet's basic communications protocols, TCP/IP, and for inspired leadership in networking. Press Release New York Times Article Biographical Information: Vinton G. CerfVinton G. Cerf, MCI Robert E. KahnRobert E. Kahn, CNRI

Linked List - II

Default Memberwise Assignment Assignment operator (=) –Can assign one object to another of same type –Default: memberwise assignment Each right member assigned individually to left member Passing, returning objects –Default: pass-by-value Copy of object passed, returned Compiler-generated copy constructor –You must provide your own copy constructor when there are member pointer variables And destructor too

Deep Copy (1 of 3) front ABC 0 itemlinkitemlinkitemlinksize 3 slist1 slist2 front XY 0 itemlinkitemlinksize 2 Consider the following two ShoppingList objects What would the result of slist2 = slist1; be if the default copy behavior took place?

Deep Copy (2 of 3) front ABC 0 itemlinkitemlinkitemlinksize 3 slist1 slist2 front XY 0 itemlinkitemlinksize 3 slist2 becomes a “shallow copy” of slist1 slist2 doesn’t get a copy of slist1 data All references to slist2 data are lost!

Deep Copy (3 of 3) front ABC 0 itemlinkitemlinkitemlinksize 3 slist1 slist2 frontsize 3 Here is what slist2 would look like as a “deep copy” of slist1 Note that slist2 has its own set of data ABC 0 itemlinkitemlinkitemlink

Clone Example (1 of 8) ShoppingList::ShoppingList(const ShoppingList &slist) { Node *cur1, *cur2; front ABC 0 itemlinkitemlinkitemlinksize 3 slist *this front XY 0 itemlinkitemlinksize 2 cur1 ? cur2 ?

Clone Example (2 of 8) this->deleteAll(); this->size = slist.size; front ABC 0 itemlinkitemlinkitemlinksize 3 front 0 size 3 cur1 ? cur2 ? slist *this

Clone Example (3 of 8) this->front = new Node(*(slist.front).item); front ABC 0 itemlinkitemlinkitemlinksize 3 frontsize 3 cur1 ? cur2 ? A itemlink 0 slist *this

Clone Example (4 of 8) cur1 = this->front; cur2 = slist.front; front ABC 0 itemlinkitemlinkitemlinksize 3 frontsize 3 cur1cur2 A itemlink 0 slist *this

Clone Example (5 of 8) while (cur2->link) { cur2 = cur2->link; cur1->link = new Node(*cur2); cur1 = cur1->link; } front ABC 0 itemlinkitemlinkitemlinksize 3 frontsize 3 cur1cur2 A itemlink slist *this B itemlink 0 First iteration

Clone Example (6 of 8) while (cur2->link) { cur2 = cur2->link; cur1->link = new Node(*cur2); cur1 = cur1->link; } front ABC 0 itemlinkitemlinkitemlinksize 3 frontsize 3 cur1cur2 A itemlink slist *this B itemlink Second iteration C 0 itemlink

Clone Example (7 of 8) cur1 = cur2 = 0; front ABC 0 itemlinkitemlinkitemlinksize 3 frontsize 3 cur1 0 cur2 0 A itemlink slist *this B itemlink C 0 itemlink

Clone Example (8 of 8) } front ABC 0 itemlinkitemlinkitemlinksize 3 frontsize 3 A itemlink slist *this B itemlink C 0 itemlink

Doubly Linked List Each node has 2 pointers, one to the node before and one to the node after No longer limited to left-to-right pointer movement Typically, a rear pointer is employed to simplify reverse traversals front A datarlinkllink B datarlinkllink C datarlinkllink rear

Circular Linked List “Last” node’s link points at the “front” node Concept of “front” optional cur A datalink B datalink C datalink E datalink D datalink