ICOM 4015 Advanced Programming

1. ICOM 4015 Advanced Programming Lecture 12 Dynamic Memory II Abstract Data Types Reading: Chapter 5 Prof. Bienvenido Vélez ICOM 4015

2. Dynamic Memory IIOutline • Abstract data types (ADT) • List Abstract Data Type • Linked list implementation of List ADT ICOM 4015

3. STACK activation records HEAP Dynamic objects ProblemNeed to Store set of Dynamic ObjectsSolution 1: Dynamic Arrays PROGRAM code Array Pointer object Global static variables p dynamic array ICOM 4015

4. STACK activation records HEAP Dynamic objects ProblemNeed to Store set of Dynamic ObjectsSolution 2: Linked Structure PROGRAM code Pointer object Global static variables p dynamic array ICOM 4015

5. A List Abstract Data Type (ADT) // lists.h // Global declarations for linked lists module // List data structures typedef int DatumType; struct Node { DatumType datum; Node* next; }; struct List { Node* first; Node* current; int length; }; // Operations on linked lists // List initialization void listInit (List& l); // List modification List& listAppend (List& l, DatumType d); List& listPrepend(List& l, DatumType d); List& listInsert (List& l, DatumType d); // List interation void listStart (List& l); void listNext (List& l); DatumType listCurrent(const List l); bool listEOL (const List l); // List printing void listDump (const List l); ICOM 4015

6. Linked lists implementation of List ADT (Part I) // lists.cc // Implementes singly linked lists ADT extern "C" { #include <stdlib.h> } #include <iostream> #include "lists.h" Node* NullNode = (Node *)NULL; // Operations on linked lists // List initialization void listInit(List& l) { l.first = NullNode; l.current = NullNode; l.length = 0; } // List modification List& listAppend(List& l, DatumType d) { Node* temp = new Node; temp->next = NullNode; temp->datum = d; if (l.first == NullNode) { l.first = temp; } else { Node* n = l.first; while(n->next != NullNode) { n = n->next; } n->next = temp; } l.length++; return l; } ICOM 4015

7. Linked lists implementation of List ADT (Part II) List& listPrepend(List& l, DatumType d) { Node* temp = new Node; temp->datum = d; temp->next = l.first; l.first = temp; } void listStart(List& l) { l.current = l.first; } void listNext(List& l) { if (l.current != NullNode) { l.current = l.current->next; } } List& listInsert(List& l, DatumType d) { Node* n = l.current; Node* temp = new Node; temp->datum = d; temp->next = l.current->next; l.current->next = temp; } DatumType listCurrent(const List l) { return l.current->datum; } bool listEOL(const List l) { return (l.current == NullNode); } ICOM 4015

8. Using the List ADT #include <iostream> #include "lists.h" int main() { List l; listInit(l); for(int i = 1; i < 10; i++) { listPrepend(l,i); } cout << "Original list" << endl; listDump(l); // Demonstrate iteration without exposing pointers for (listStart(l); !listEOL(l); listNext(l)) { DatumType curr = listCurrent(l); cout << "Next datum: " << curr << endl; } listStart(l); listNext(l); listInsert(l,100); cout << "List with 100 inserted" << endl; listDump(l); } IMPORTANT The fact that the list is implemented using pointers remains hidden from users of the module. The implementation ABSTRACTS OUT irrelevant detail ICOM 4015

9. List ADT Output [bvelez@amadeus] ~/icom4015/lec15 >>g++ lists.cc main.cc -o lists [bvelez@amadeus] ~/icom4015/lec15 >>lists Original list 9 8 7 6 5 4 3 2 1 Next datum: 9 Next datum: 8 Next datum: 7 Next datum: 6 Next datum: 5 Next datum: 4 Next datum: 3 Next datum: 2 Next datum: 1 List with 100 inserted 9 8 100 7 6 5 4 3 2 1 [bvelez@amadeus] ~/icom4015/lec15 >> ICOM 4015

10. Abstract Data Types (ADT)Summary • Consists of the definition of a type of object and a set of operations that can be performed on object of the type • An ADT describes a type of object together with the set of operations defined on the object • An ADT hides irrelevant implementation details • An ADT shields its users from dependencies on hidden details ICOM 4015