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CSE 222 : ObjectOriented Programming

Lecture 1: Introduction toObject Oriented Programming

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Topics to be Covered

Introduction to Object-Oriented Concepts

What is an Object?

What can & cant be a Object

Classes Basic Concepts of OOP

Encapsulation

Polymorphism

Inheritance

The Origins of C++

Advantages of C++

A way to OOP

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Introduction to Object-Oriented

Concepts

Object orientation allows to constructsystems

based on the idea of components.

This component-based development allowsobjects to be

re-used

extended

reducing development time dramatically.

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Introduction to Object-Oriented

Concepts cont..

Object-oriented programming allows the following: A system can be constructed from a set of objects

just as a house is built from bricks, windows and doors

Adding new capabilities to existing objects can expand asystem

A door for a house could be a door to a room a cupboard this could be extended to include garage doors.

Creating new objects can expand a system a house object may have stairs or a lift. No stairs could mean a bungalow

stairs would allow the house to have more than one floor a lift would allow a tall block of flats to be built.

Reduces the development time by facilitating re-use The bricks, windows and door objects, which were designed for the

first house, can also be used to build other houses.

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What is an Object? The world around us is full of objects and modern software

aims to imitate the real world. objects have state (variables) and behaviour (method). An objects state can be thought of as the features that

describe it a carmay have an engine type, a make, model numberand a

colour.

An objects behaviours are the things that it knows how todo accelerate brake

change gear turn the windscreen wipers on and off.

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What can & cant be a Object

An object can be: A physical thing in the real world.

A representation of reality.

A tangible or visible thing.

A thing to which action or thought can be directed. Passive doing nothing until activated e.g. a switch.

Active continually monitoring until conditions change,e.g. a

thermostat.

An object is never: A value (e.g. name).

A process (e.g. sort).

Time (e.g. five minutes).

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Classes

A class is a template definition of themethods and variables in a particularkind of object .

an object is a specific instance of a class;it contains real values instead of variables.

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Basic Concepts of OOP

Object-Oriented Programming consists of 3primary ideas: Encapsulation

Is a black box technique The mechanism that binds together code and data it

manipulates Keeps both safe from outside interference and misuse Operations on the data are considered to be part of the

data type We can understand and use a data type without knowing

all of its implementation detailsNeither how the data is represented nor how the operationsare implemented

We just need to know the interface (or method headers) how to communicate with the object

Compare to functional abstraction with methods

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Inheritance

Process by which oneobject can acquire theproperties of anotherobject

Properties of a datatype can be passeddown to a sub-type we can build newtypes from old ones

We can build classhierarchies with manylevels of inheritance

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Polymorphism

In the context of object-oriented programming, isthe ability to create avariable, a function, or an

object that has more thanone form.

Polymorphism ismanifested in the form ofmultiple methods havingthe same name.

operations can have thesame name even thoughthey are associated withdifferent objects.

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The Origins of C++

It was developed by Bjarne Stroustrupin1979 at Bell Labs

As an enhancement to the C programming

language and originally named "CwithClasses".

C++ is an object oriented programming

language. It was renamed to C++ in 1983.

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The origins of C++ cont.. C++ is designed to be a statically typed general-purpose

language that is as efficient and portable as C C++ is designed to directly and comprehensively support

multiple programming styles (procedural programming,data abstraction, object-oriented programming, and

generic programming) C++ avoids features that are platform specific or not

general purpose

C C++

Templates

class

Operatoroverloading

Virtualfunctions

Multipleinheritance

Exceptionhandling

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Advantages of C++

Can handle more complex program (ifLOC>25,000 100,000 it becomes socomplex to handle in C)

C++ allows the programmer tocomprehend and manage larger, morecomplex programs

STL is there which provides genericroutines to manipulate data.

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Towards OOP

Structured Programming Method (SPM):

Invented in 1960s

Method was encouraged by C and Pascal

Fairly ease to write moderately complexprograms

Support stand-alone subroutine, localvariables, rich control structures & eliminate

GOTO Reach their limit when project becomes too

large

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Breaking the Barriers of SPM

OOP Took the best ideas of SPM and combine with several

new concepts.

Program Organization Around its code :

what is happening

Structured Programming uses this organization

Programs are organized around code

Code acting on data

Around its data : who is being affected

Datacontrolling access ofcode

Define data and routines that permitted to act on data

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Readings

Chapter 11 : An Overview of C++, TheComplete Reference : C++, By- HerbertSchildt, 4th Edition, pp:256-259

Chapter 1: Introduction to Programming,Programming Methods, NCC EducationLimited, pp: 1-14 to 1-26