Stack Lesson xx

1. Stack Lesson xx

2. Objectives • Difference between a queue and a stack • Building a stack • Pushing items onto a stack • LIFO vs FIFO • Stack variation

3. Queue vs. Stack e 0 Head Node added at the end queue a b c d Head e a b c d 0 Node added at the beg. stack

4. (Part 1) Program to Create a Stack struct entry { int value;   entry* next; }; entry* stackAdd(entry*, entry*); // prototype void printList(const entry*); // prototype int main() { entry* temp, * head = 0; // initially empty list   for (inti = 0; i < 5; i++) //loop to create 5 nodes   {     temp = new entry; // dynamic memory allocation cin >> temp->value; // initialize data value     head = stackAdd(head, temp);   } printList(head);   return 0; }

5. (Part 2) Program to Create a Stack // function to add a new node to the head of a linked list entry* stackAdd(entry* h, entry* t) {   t->next = h; // put new node at front of list   h = t; // denote new node as new head of list   return h; // return new head's address } void printList(const entry* h) // prints the list {   for (const entry* p = h; p; p = p->next)   { cout << "node address: " << p       << " value " << p->value       << " next " << p->next << endl;   } }

6. Starting the Stack struct entry { int value;   entry* next; }; int main() {   entry* temp, * head = 0; // initially empty list temp head 0

7. Loop for Input and Creating Additional Nodes    for (inti = 0; i < 5; i++) //loop to create 5 nodes   {     temp = new entry; // dynamic memory allocation cin >> temp->value; // initialize data value     head = stackAdd(head, temp);   } (76c) 76c 11 temp head 0

8. Calling stackAdd( ) Function        head = stackAdd(head, temp); entry* stackAdd(entry* h, entry* t) h 0 (76c) head 11 0 76c 76c temp t

9. entry* stackAdd(entry* h, entry* t) {   t->next = h; // put new node at front of list   h = t; // denote new node as new head of list   return h; // return new head's address } stackAdd( ) Function h h 0 76c (76c) (76c) head head 11 11 0 0 0 76c 76c 76c 76c t temp temp t

10. entry* stackAdd(entry* h, entry* t) {   t->next = h; // put new node at front of list   h = t; // denote new node as new head of list   return h; // return new head's address } Returning a pointer from a Function h 76c (76c) (76c) head head 11 0 11 0 76c 0 76c 76c 76c temp temp t

11. 2nd iteration of the for loop for (inti = 0; i < 5; i++) //loop to create 5 nodes   {     temp = new entry; // dynamic memory allocation cin >> temp->value; // initialize data value     head = stackAdd(head, temp);   } (76c) (76c) head head 11 0 11 0 76c 76c (99b) 76c 22 99b temp temp

12. 2nd Call to Function stackAdd( ) entry* stackAdd(entry* h, entry* t) {   t->next = h; // put new node at front of list   h = t; // denote new node as new head of list   return h; // return new head's address } h 76c (76c) head 11 0 76c (99b) 22 99b t 99b temp

13. After Executing First 2 Lines of the 2nd Call to stackAdd () Function entry* stackAdd(entry* h, entry* t) {   t->next = h; // put new node at front of list   h = t; // denote new node as new head of list   return h; // return new head's address } h 99b (76c) head 11 0 76c (99b) 22 76c 99b t 99b temp

14. After Executing First 2 Lines of the 2nd Call to stackAdd () Function entry* stackAdd(entry* h, entry* t) {   t->next = h; // put new node at front of list   h = t; // denote new node as new head of list   return h; // return new head's address } (76c) head 11 0 99b (99b) 22 76c 99b temp

15. End of the Loop head 55 44 33 22 11 0

16. Printing the Linked List   // traverse the list for (entry* p = head; p; p = p->next)   { cout << "node address: " << p       << " value " << p->value       << " next " << p->next << endl;   } head 55 44 33 22 11 0 p temp

17. Output node address: 5ae value 55 next 88b node address: 88b value 44 next 4af node address: 4af value 33 next 57d node address: 57d value 22 next 76c node address: 76c value 11 next 0 (5ae) (57d) (88b) (4af) (76c) 22 76c 11 0 44 4af 55 88b 33 57d head 5ae 4af temp

18. Variations of a Linked List   for (inti = 0; i < 5; i++)   {     temp = new entry; cin >> temp->value;     head = stackAdd(head, temp);   } int n; cout << “How many nodes ? “; cin >> n;   for (inti = 0; i < n; i++)   {     temp = new entry; cin >> temp->value;     head = stackAdd(head, temp);   }

19. Summary Difference between a queue and a stack Building a stack Pushing items onto a stack LIFO vs FIFO Stack variation