-
8/7/2019 oopweek1
1/20
1
Object Oriented Programming
Development
-
8/7/2019 oopweek1
2/20
2
What is Object Oriented
Programming?
An object is like ablack box.
The internaldetails arehidden.
Identifying objects andassigning responsibilities to
these objects. Objects communicate to
other objects by sendingmessages.
Messages are received bythe methods of an object
-
8/7/2019 oopweek1
3/20
3
What is an object?
Tangible Things as a car, printer, ...
Roles as
Incidents as flight,
Interactions as contract, sa
Specifications as colour, shape,
-
8/7/2019 oopweek1
4/20
4
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.
-
8/7/2019 oopweek1
5/20
5
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.
-
8/7/2019 oopweek1
6/20
Example: The Person class
#include
#include
class Person{
char name[20];
int yearOfBirth;public:
void displayDetails() {
cout
-
8/7/2019 oopweek1
7/20
7
The two parts of an object
Object = Data + Methods
or to say the same differently:
An object has the responsibility to know andthe responsibility to do.
= +
-
8/7/2019 oopweek1
8/20
Basic Terminology
Abstraction is the representation of theessential features of an object. These are
encapsulated into an abstract data type. Encapsulation is the practice of including in
an object everything it needs hidden from
other objects. The internal state is usuallynot accessible by other objects.
-
8/7/2019 oopweek1
9/20
Basic Terminology:
Inheritance
Inheritance means that one class inheritsthe characteristics of another class.
This is also called a is a relationship:
A car is a vehicle
A teacher is a person
A dog is an animal
-
8/7/2019 oopweek1
10/20
10
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).
-
8/7/2019 oopweek1
11/20
11
Basic Terminology:
Aggregation
Aggregation describes a has arelationship. One object is a part of
another object.
We distinguish between composite
aggregation (the composite owns thepart) and shared aggregation (the part is
shared by more then one composite).
A car has wheels.
-
8/7/2019 oopweek1
12/20
12
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 amessage to the object (usually by callinga method).
-
8/7/2019 oopweek1
13/20
13
The two steps of Object
Oriented Programming
MakingClasses: Creating, extendingorreusingabstract datatypes.
MakingObjectsinteract: Creatingobjectsfrom abstract datatypesand defining
their relationships.
-
8/7/2019 oopweek1
14/20
14
Historical Notes
C++ owes most to C.Other ancestors are Simula67and Algol68.
First versions ofC++ 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
-
8/7/2019 oopweek1
15/20
15
C++ and C
C is a subset ofC++.Advantages: ExistingC libraries canbe
used, efficient code canbe generated.But: C++ has the same caveats andproblems as C (e.g. pointer arithmetic,).
C++ canbe usedboth as a low level andas a high level language.
-
8/7/2019 oopweek1
16/20
16
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.
-
8/7/2019 oopweek1
17/20
17
Module Outline
Introduction
The non object
oriented basics Classes
Design Approaches
Testing
Inheritance
Aggregation
Polymorphism Multifile Development
-
8/7/2019 oopweek1
18/20
18
Assessment Details
50% in course and 50% exam.
For more details for the in course
assignment see separate handout.
-
8/7/2019 oopweek1
19/20
19
Books
Teach YourselfC++ in 10 minutes,J. Liberty, SAMS 1999.
C++ - How to program, Deitel & Deitel,Prentice Hall, 2001.
Object OrientedProgramming with C++,
DavidParson, Letts Educational, London1997.
-
8/7/2019 oopweek1
20/20
20
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 ofC++:http://www.research.att.com/~bs