Transcript The Introduction to Object

CIS601: Object-Oriented
Programming in C++
Lesson #1
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Note: CIS 601 notes were originally developed by H. Zhu for NJIT DL Program. The notes were subsequently revised by M. Deek.
Contact Information
Email: [email protected]
Web: www.ccs.njit.edu/maura
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Goals for the Course
To
understand Object Oriented
programming
To further develop your C++ skills
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Course Coverage
 Fundamentals
of object-oriented
programming
*Data abstraction
*Encapsulation
*Inheritance
*Dynamic binding
*Polymorphism
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Course Coverage cont.
C++
will be used as a vehicle to
illustrate and implement OOP
concepts.
Object-oriented paradigm will be
applied to design and programming.
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Course Coverage cont.
 Effects
of OO methodology on software
design
 maintenance
 extensibility
 reusability
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Prerequisites
 Working
knowledge of
 C/C++
 Familiarity
with operating systems
 Familiarity with compilers
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Lectures
 1.
Introduction to Object-Oriented
Programming
 2.
 3.
Overview of basic structures of C++
Objects and Classes
 4. Objects and Classes in C++
 5. Inheritance
 6. Inheritance in C++
 7. Polymorphism and That in C++
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Lectures cont.
 8.
 9.
Operator Overloading in C++
Templates and Friends in C++
 10. I/O Streams in C++
 11. Exception Handling in C++
 12. Container Classes in C++
 13. Object-Oriented Analysis and Design
 14. Case Studies and Review
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Thinking Methodology
Induction
From
specialization to generalization
create the word “dog” from different
dogs
to
Dog
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Thinking Methodology
Deduction(infer)
From
generalization to specialization
the word “dog” you have learned
that an animal is or is not a dog.
From
DOG
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Design Methodologies
 Functional
 The
decomposition (Top-Down)
whole system is characterized by a
single function, and then the function is
decomposed into a set of functions in a
process of stepwise refinement.
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Functional decomposition
The System
Function1
Desk
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Function2
Table top
Studying
Function3
... ...
Filing cabinet Bookshelves
... ...
... ...
Function11
Function12
Left drawer
Middle drawer Right drawer
Design Methodologies
 Functional
 To
composition (bottom-up)
create different components of a
function from a library of functions.
 To integrate components into a module
and form a more significant function.
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Functional composition
The System
Function1
Desk
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Function2
Table top
Studying
Function3
... ...
Filing cabinet Bookshelves
... ...
... ...
Function11
Function12
Left drawer
Middle drawer Right drawer
Functional (De)Composition
Modules
with well-defined semantics
that can be directly implemented.
Procedures own the data.
Data plays a secondary role.
Does not necessarily reflect the
states of abstraction in the
application.
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Object-Orientation
 A thinking
methodology
 Everything
is an object.
 Any system is composed of objects (a system
is also an object).
 The evolution and development of a system
is caused by the interactions of the objects
inside/outside a system.
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Everything is an object
A student, a professor
 A desk, a chair, a classroom, a building
 A university, a city, a country
 The world, the universe
 A subject such as CS, IS, Math, History, …

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Systems are composed of
objects
 An
educational system
 An economic system
 An information system
 A computer system
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The development of a system is
caused by interactions
 NJIT
is defined by the interactions
among:
 students
 professors
Inside NJIT
 staff
 Board
governance
 State governance
 … ...
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Outside NJIT
Design Methodologies
 Object-Orientation
is a design
methodology(OOA/OOD)
 Objects
are the building blocks of a
program (interface, editor, menu, file,
etc.); data managing object (db), etc.)
 Objects represent real-world
abstractions within an application.
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Design Methodologies
Object-orientation

induction: objects -> a class
This

needs tools
and deduction: a class ->objects
This
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supports
needs programmers
Design Methodologies
Object-orientation
Top-down:
supports
from a super-class to sub-
classes
Bottom-up: from sub-classes to a
super-class
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Programming Techniques
The
evolution of programming
techniques is
to
make languages more expressive
to control complex systems more
easily
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Abstract Data Types(ADTs)
 Abstraction
 Properties
 Abstract
Data Types and ObjectOrientation
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Abstraction
 to
understand a problem by
separating necessary from
unnecessary details
 To define the interface to a data
abstraction without specifying
implementation detail.
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Abstraction
Problem
Model
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Properties of ADT
 With
abstraction, you create a welldefined entity
 These entities define the data
structure as a set of items.
 For
example, each employee has a name,
date of birth, and social number...
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Properties of ADT(Cont.)
 The
data structure can only be
accessed with defined operations.
 This
 An
set of operations is called the interface
entity with these properties is
called an abstract data type (ADT).
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ADT
Abstract
Data Type
Abstract Data Structure
Interface
Operations
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Definition (ADT)
 ADT
is characterized by the following
properties:
 1.
It exports a type.
 2. It exports a set of operations.
 3. Operations of the interface are the only
access mechanism to the data structure.
 4. Axioms and preconditions define the
application domain of the type.
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Example: ADT List
 Type
List.
 The interface to instances of type List is
defined by the interface definition file.
 Operations: insert, get, append, delete,
search,…
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List
 The
application domain is defined by the
semantical meaning of the provided
operations. Axioms and preconditions
include statements such as
 ``An
empty list is a list.''
 ``Let l=(d1, d2, d3, ..., dN) be a list. Then
l.append(dM) results in l=(d1, d2, d3, ..., dN,
dM).''
 ``an element of a list can only be deleted if the
list is not empty.''
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Encapsulation
 Combines
the data and the operations
 Encloses both variables and functions
 Keeps details of data and operations
from the users of the ADT
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Encapsulation (cont.)
 Allows
for modularity
 Controls access to data
 Separates implementation from
interface
 Extends the built-in types
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Object-Oriented Programming
 Objects
are derived from ADTs.
 Interacting objects handle their own
house-keeping.
 Objects in a program interact by
sending messages to each other.
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Object1
Data1+Procedures1
Object2
Data
Data
Data12
2 + Procedures
Object3
Data3 + Procedures3
Object4
Data4 + Procedures4
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Object-Oriented Programming
Each
object is responsible to
initialize and destroy itself.
Therefore, there is no need to
explicitly call a creation or
termination procedure.
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ADT and Object-Orientation
 ADTs
allow for the creation of instances
with well-defined properties and behavior.
 In object-orientation, ADTs are referred to
as classes.
 Therefore, a class defines the properties
of objects called instances.
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ADT and Object-Orientation
 ADTs
define functionality by emphasizing the
involved data, their structure, operations,
axioms and preconditions.
 Object-oriented programming is
``programming with ADTs'': combining
functionality of different ADTs to solve a
problem.
 Therefore, instances (objects) of ADTs
(classes) are dynamically created, destroyed
and used.
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Inheritance(Hierarchy)
 Expresses
commonality among objects
 Allows code reusability
 Highlights Generalization/Specialization
relationships
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Polymorphism
The
ability of objects to
respond differently to the same
message or function call.
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Object-Orientation Evolution
 Modules
 Information
hiding
 Data encapsulation
 Abstract data types
 Objects
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Remember:
 Encapsulation
(Data & Operations)-- A
technique for Information Hiding. The
users of the objects do not need to
know the details of the data and
operations of the objects.
 Data Abstraction -- the procedure to
define a class from objects.
 Abstract Data Type-- Class.
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Objects and Large Software
Systems
 Object
view
 Makes
systems more understandable
 Unifies design and programming
methods
 Initial program thoughts are informal
objects-and-interactions, even when
using non-OO languages.
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Objects and Large Software Systems
Divides
code into logical chunks
Allows for "off-the-shelf" code libraries
to be reused
Supports code evolution: internals can
always be re-written as long as
interface stays the same
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Reading


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Chapter 1 Sections 1.1-1.2
Chapter 5 Sections 5.1-5.2