Chapter 5 – Dynamic Data StructurePar1: Abstract Data Type

DATA STRUCTURES & ALGORITHMS

Teacher: Nguyen Do Thai NguyenE-mail: nguyenndt@hcmup.edu.vnPhone: 0906667597Group: https://www.facebook.com/groups/335118686690998

Ho Chi Minh City University of Pedagogy

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Abstract Data Type (ADT)

Overview object oriented

programming

Pointer and Dynamic

memory allocation

Outline

1. Abstract Data Type

• It’s a data type• It can hold both data and operation• An ADT is a collection of data and associated

operations for manipulating that data • ADT support abstraction, encapsulation, and

information hiding 

1. Abstract Data Type

1. Abatract Data Type

• ADT C++: class • Examples

– the set ADT• A set of elements• Operations: union, intersection, size and complement

– the queue ADT• A set of sequences of elements• Operations: create empty queue, insert, examine, delete,

and destroy queue

– Stack ADT– List ADT

The List ADT

• Concept: A sequence of zero or more elements

A1, A2, A3, … AN

• Member data:– Size (N): length of the list– List Contents:

• A1: first element

• AN: last element

The List ADT

• Operations:– printList: print the list– makeEmpty: create an empty list– find: locate the position of an object in a list

• list: 34,12, 52, 16, 12• find(52) 3

• Two standard implementations for the list ADT– Array-based– Linked list

The List ADT

Operations:• insert: insert an object to a list

– insert(x,3) 34, 12, 52, x, 16, 12

• remove: delete an element from the list– remove(52) 34, 12, x, 16, 12

• findKth: retrieve the element at a certain position

Array

• Elements are stored in contiguous array positions

Linked List

• Ensure that the list is not stored contiguously– use a linked list– a series of structures that are not necessarily adjacent

2. Overview object oriented programming

• Class is a template that include data and

functions operating on these data (attribute and

method – data member and function member)

– A class represents a set of objects that have

common properties

• Object is an instance of a class, an entity

created using a class definition.

Exampleobject

class

2. Overview object oriented programming

• Object-Oriented Design Principles– Abstraction– Encapsulation– Modularity.

2. Overview object oriented programming

• Class declaration in c++:

class ClassName

{

public:

memberFunction1();

memberFunction2();

…………..

private:

DataType1 memberdata1;

DataType2 memberdata2;

…………….

};

privateprotected

public

3. Pointer and Dynamic memory allocation

Memory Management

• Static Memory Allocation– Memory is allocated at compilation time

• Dynamic Memory– Memory is allocated at running time

Static vs. Dynamic Objects

• Static object

(variables as declared in function calls)

– Memory is acquired automatically

– Memory is returned automatically when object goes out of scope

• Dynamic object

– Memory is acquired by program with an allocation request

• new operation

– Dynamic objects can exist beyond the function in which they were allocated

– Object memory is returned by a deallocation request

• delete operation

Memory Allocation

{ int a[200]; …}

int* ptr;ptr = new int[200];…delete [] ptr;

newdelete

Object (variable) creation: New

Syntax

ptr = new SomeType;

where ptr is a pointer of type SomeType

p

Uninitialized int variable

Example

int* p = new int;

Object (variable) destruction: Delete

Syntax

delete p; storage pointed to by p is returned to free store and p is now

undefined

p

Exampleint* p = new int;*p = 10;delete p;

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Array of New: dynamic arrays

• Syntax

P = new SomeType[Expression];– Where

• P is a pointer of type SomeType• Expression is the number of objects to be

constructed -- we are making an array

• Because of the flexible pointer syntax, P can be considered to be an array

Example

Dynamic Memory Allocation Request for “unnamed” memory from the Operating System

int *p, n=10;p = new int;

p = new int[100];

pnew

pnew

p = new int[n]; pnew

Memory Allocation Example

Want an array of unknown sizemain(){ cout << “How many students? “; cin >> n;

int *grades = new int[n];

for(int i=0; i < n; i++){ int mark; cout << “Input Grade for Student” << (i+1) << “ ? :”; cin >> mark; grades[i] = mark; }

. . . printMean( grades, n ); // call a function with dynamic array . . . }

Freeing (or deleting) Memory

– Declaration: <class name>* namePtr;– Access:

namePtr->memberData;

namePtr->memberFunction();

or

(*namePtr).memberData;

(*namePtr).memberFunction()

Object pointer