Unit 1 - Introducing Abstract Data Type (ADT) Part 1

Unit Objectives Solve a problem using a concrete data type (CDT) ◦ Apply 4 steps of software development process  Side trip -> UML class diagram Solve same problem using an abstract data type ◦ Introduce abstract data type (ADT) ◦ Introduce our first ADT -> List  Design ADT List  First implementation: array-based List  Side trip -> pointers and linked lists  Second implementation: link-based List ◦ Compare both ADT List implementations  Side trip -> efficiency analysis CMPT Anne Lavergne2

What is a Concrete Data Type (CDT)? Term used to contrast with Abstract Data Type (ADT) Definition ◦ Data structure, i.e., constructs, available as part of a programming language, in which we store data Examples: ◦ array ◦ linked list: classes and pointers CMPT Anne Lavergne3

Review: The 4 Steps of the Software Development Process Step 1: Problem statement Step 2: Design Step 3: Implementation Step 4: Testing CMPT Anne Lavergne4

Step 1 - Problem Statement FriendsBook Application ◦ Design and implement an application that maintains the data for a simple social network. ◦ Each person in the network must have a profile that contains the person’s name, optional image, current status and a list of friends. ◦ Your application must allow a user to join the network by creating a profile, leave the network modify the profile, search for other profiles, and add friends. Source: Textbook - Programming Problem 11 - Chapter 9 - Page 287 CMPT Anne Lavergne5

Step 1 - Question Is the problem statement clear and unambiguous? CMPT Anne Lavergne6

Why is Step 1 important! This quote demonstrates why problem statement must be clear and unambiguous before we move on to the other steps of software development process CMPT Anne Lavergne7

Step 2 - OO Design Model “entities” from problem statement Using: ◦ “Noun” technique to figure out what could be a classes and what could be its attributes ◦ OO Principles:  Encapsulation  Information hiding  Single responsibility CMPT Anne Lavergne8

Step 2 - OO Design Choose appropriate ADT ◦ In this first implementation of our FriendsBook application, we shall choose a CDT instead 3. Record our design ◦ Use UML class diagram 4. Specify behaviour of our program ◦ Write algorithm (in pseudocode) CMPT Anne Lavergne9

Side Trip - UML

UML: Unified Modeling Language Object-Oriented Paradigm modelling notation Role: clear and effective way to represent (model) various aspects of software system Includes variety of techniques Programming language independent Flexible: allow models to evolve from one phase to another In this course, we will use UML Class Diagrams CMPT Anne Lavergne11

UML Class Diagram contains… Class ◦ Attributes ◦ Operations Relationship between classes ◦ Generalization (is-a) ◦ Aggregation (has-a) ◦ Dependency (uses) ◦ Multiplicity + other details CMPT Anne Lavergne12

CMPT Anne Lavergne13 Class Class Name Attributes Operations - account ID - customer - balance + deposit(…) + withdraw(…) Example: Exclude constructors, destructors, getters/setters. Why? Because we assume that we will develop these methods for our classes, if they are needed. Account How to represent a class in UML

UML class diagram for our FriendsBook Application CMPT Anne Lavergne14 FriendsBook - numberOfMembers : integer - members : Profile[0..*] + join( newProfile : Profile ) : void + leave( profile : Profile ) : void + modify( profile : Profile ) : void + search( target : String ) : Profile Profile - name : String - image : String - status : String - numberOfFriends : integer - friends : String[0..*] 0..* + addFriend( aFriend : String ) : void

Step 3 - Solution #1 – Code Posted on our course web site Week 2: ◦ Code demonstrating class testing with a Test Driver:  FriendsBook version 1 Profile.h, Profile.cpp, FriendsBook.cpp (Test Driver), MakefileProfile.hProfile.cppFriendsBook.cppMakefile ◦ Code demonstrating Incremental Development + use of CDT:  FriendsBook version 2 FriendsBook.cpp and version 3 FriendsBook.cppFriendsBook.cpp CMPT Anne Lavergne15

Documentation Header Comment Block Class description Class Invariant Method description Preconditions Postconditions CMPT Anne Lavergne16

Solution #1 – Disadvantages of having client code manipulating data directly 1. FriendsBook has many responsibilities: ◦ Interface with the user ◦ Manage data ( Profile objects) CMPT Anne Lavergne17

Observation: Client Code versus CDT Our FriendsBook (client code) manipulates the data, i.e., the array (CDT or data structure) containing Profile objects directly array Directly access data FriendsBook (client code) CMPT Anne Lavergne18

Solution #1 – Disadvantages of having client code manipulating data directly 2. Difficult to reuse the same data collection (array + functions to manipulate its data) in another application CMPT Anne Lavergne19