1-Object Oriented Programming Development-University of Luton

7/29/2019 1-Object Oriented Programming Development-University of Luton

1/21

1

Object Oriented Programming

Development

By:

Marc Conrad

University of Luton

Email:

[email protected]:

D104


2/21

2

What are we doing today?

Introduction of:

the lecturer

ObjectsBasic Terminology

C++

the module


3/21

3

What is Object Oriented

Programming?

An object is like ablack box.

The internaldetails arehidden.

Identifying objectsandassigning responsibilitiesto

these objects.Objects communicate to

other objects by sendingmessages.

Messages are received bythe methodsof an object


4/21

4

What is an object?

Tangible Things as a car, printer, ...

Roles as employee, boss, ...

Incidents as flight, overflow, ...

Interactions as contract, sale, ...

Specifications as colour, shape,


5/21

5

So, what are objects?

an object represents an individual,identifiable item, unit, or entity, either

real or abstract, with a well-defined rolein the problem domain.

Or

An "object" is anything to which aconcept applies.

Etc.


6/21

6

Why do we care about

objects?

Modularity - large software projectscan be split up in smaller pieces.

Reuseability - Programs can beassembled from pre-written softwarecomponents.

Extensibility - New softwarecomponents can be written ordeveloped from existing ones.


7/21

Example: The Person class

#include

#includeclass Person{

char name[20];

int yearOfBirth;

public:

void displayDetails() {

cout


8/21

8

The two parts of an object

Object = Data + Methods

or to say the same differently:

An object has the responsibility to knowandthe responsibility to do.

= +


9/21

9

Basic Terminology

Abstractionis the representation of theessential features of an object. These are

encapsulated into an abstract data type.Encapsulationis the practice of including

in an object everything it needs hidden

from other objects. The internal state isusually not accessible by other objects.


10/21

10

Basic Terminology:

Inheritance

Inheritance means that one class inheritsthe characteristics of another class.

This is also called a is a relationship:

A car is avehicle

A teacher is aperson

A dog is ananimal


11/21

11

Basic Terminology:

Polymorphism

Polymorphism means having manyforms. It allows different objects to

respond to the same message in differentways, the response specific to the type ofthe object.

E.g. the message displayDetails()of thePerson class should give different resultswhen send to a Student object (e.g. theenrolment number).


12/21

12

Basic Terminology:

Aggregation

Aggregation describes a hasarelationship. One object is a part of

another object.

We distinguish between composite

aggregation (the composite owns thepart) and sharedaggregation (the part is

shared by more then one composite).

A car has wheels.


13/21

13

Basic Terminology:

Behaviour and Messages

The most important aspect of an object isits behaviour(the things it can do). A

behaviour is initiated by sending amessageto the object (usually by callinga method).


14/21

14

The two steps of Object

Oriented Programming

Making Classes:Creating, extending orreusing abstract data types.

Making Objects interact:Creating objectsfrom abstract data types and defining

their relationships.


15/21

15

Historical Notes

C++ owes most to C.Other ancestors are Simula67and Algol68.

First versions of C++ in 1980 under thename C with classes. Since 1983 thename C++ is used.

1990: ANSI/ISO 9899 defines a standardfor C

1998: ISO/IEC 14882 specifies the

standard for C++

C++ 1987


16/21

16

C++ and C

C is a subset of C++.Advantages:Existing C libraries can be

used, efficient code can be generated.But:C++ has the same caveats andproblems as C (e.g. pointer arithmetic,).

C++ can be used both as a low levelandas a high levellanguage.


17/21

17

C++ and Java

Java is a full object oriented language, allcode has to go into classes.

C++ - in contrast - is a hybrid language,capable both of functional and objectoriented programming.

So, C++ is more powerful but alsomore difficult to handle than Java.


18/21

18

Module Outline

Introduction

The non object

oriented basicsClasses

Design Approaches

Testing

Inheritance

Aggregation

PolymorphismMultifile Development


19/21

19

Assessment Details

50% in course and 50% exam.

For more details for the in course

assignment see separate handout.


20/21

20

Books

Teach Yourself C++ in 10 minutes,J. Liberty, SAMS 1999.

C++ - How to program, Deitel & Deitel,Prentice Hall, 2001.

Object Oriented Programming with C++,

David Parson, Letts Educational, London1997.


21/21

21

Websites

A C++ online tutorial:http://www.cplusplus.com/doc/tutorial/

The C++ FAQ:http://www.parashift.com/c++-faq-lite

The homepage of Bjarne Stroustrup, the

inventor of C++:http://www.research.att.com/~bs

Documents

1-Object Oriented Programming Development-University of Luton