01 iec t1s1 oops session 01

8/14/2019 01 Iec t1s1 Oops Session 01

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Slide 2 of 45Session 1Ver. 1.0

Object-Oriented Programming Using C#

In this session, you will learn to:

Explain features of the object-oriented methodology

Describe the phases of the object-oriented methodology

Define classes in C#

Declare variablesWrite and execute C# programs

Objectives


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Object orientation is a software development methodology

that is based on modeling a real-world system.

An object oriented program consists of classes and objects.

Let us understand the termsclass and objects

Object-Oriented Methodology


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Toyota CamrySuzuki Reno Honda Acura

Objects

Class

Object-Oriented Methodology (Contd.)

Car


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An object means a material thing that is capable of being

presented to the senses.

An object has the following characteristics:

It has a state

It may display behaviorIt has a unique identity

Objects interact with other objects through messages.

Let us understand these concepts.

The Foundation of Object Orientation


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Car positioned at one place defines its State

Movement of car defines its Behavior

Car number XX 4C 4546 shows

the Identity of the car

The Foundation of Object Orientation (Contd.)


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Car is flashing the lights to pass

the message to the other car

The Foundation of Object Orientation (Contd.)




Just a minute

Identify the possible states of the following objects:

1. A cell phone

2. A stereo

Solution:1. States of a cell phone: Off, Ring, Vibrate, and Call

2. States of a stereo: Play, Pause, Rewind, and Forward




Just a minute

Dr. James and Mr. Hyde went to the railway station to book

tickets for 3rd December. At the railway station, they requested

the clerk at the ticket counter to book two tickets for the Flying

Express in the first class. Identify the following:

1. The possible receiver of the message in this situation.

2. The possible method that the receiver can use.

Solution:

1. The receiver of the message in this case will be the clerk at

the ticket counter.2. The clerk will check if two tickets are available on the

requested train in the desired class and for the desired date. If

the tickets are available, the clerk will enter the details (name,

age, departure date, and seat), confirm the reservation, and

collect the required fare.




Characteristics of the Object-Oriented Approach

Realistic modeling

Reusability

Resilience to change

Existence as different forms




Just a minute

State whether the following situations demonstrate

reusability:

1. Recycling paper

2. Pump reusability (same pump is used in a well and in a fuel

station)

Solution:

1. It does not represent reusability because the unusable paper

is destroyed before paper is recycled for use. The unusable

paper loses its identity and cannot be considered the same as

recycled paper.2. It represents reusability because a pump can be used for

suction of water as well as petrol. It is not necessary to use

the same pump in both the cases. Two separate machines

can be used because both belong to the Pump class.




The following phases are involved in the software

development:

The Analysis phase

The Design phase

The Implementation phase

Let us discuss the process of constructing a building.

Phases of Object Orientation




Just a minute

As a member of a team that is developing software for

DialCom Telecommunications, Inc., you have been

assigned the task of creating a software module that

accepts and displays customer details such as name, age,

and phone number. Identify the class that you will create

and the methods of the class.

Solution:

As per the problem statement, the class required is:

Customer

The class should have the methods to:

Accept customer details

Display customer details




A program is a set of instructions to perform a specific task.

Programming languages use programs to develop software

applications.

A compiler is a special program that processes the

statements written in a particular programming languageand converts them into a machine language.

This process of conversion is called compilation.

Introducing C#




C#, also known as C-Sharp, is a programming language

introduced by Microsoft.

C# is specially designed to work with the Microsofts .NET

platform.

Let us understand the structure of a C# program.

Introducing C# (Contd.)




Consider the following code example, which defines a class:

public class Hello

{

public static void Main(string[] args)

{System.Console.WriteLine("Hello, World!

\n");

}

}

Classes in C#




public class Hello

{

public static void

Main(string[] args)

{

System.Console.WriteLine("He

llo, World! \n");

}

}

Classes in C# (Contd.)

The class Keyword

Is used to declare a

class




public class Hello

{

public static void

Main(string[] args)

{


llo, World! \n");

}

}

The class Name

Is used as an identifier

for a class





public class Hello

{

public static void

Main(string[] args)

{


llo, World! \n");

}

}

The Main() Function

Is the entry point of an

application

Is used to create

objects and invokemember functions





public class Hello

{

public static void

Main(string[] args)

{


llo, World! \n");

}

}

System.Console.WriteLine()

Displays the enclosed text on

the screen





public class Hello

{

public static void

Main(string[] args)

{


llo, World! \n");

}

}

The Escape Character

Displays New line

character. Other special

characters can also be

displayed such as \t, \b

and \r





Demo: Creating Classes

Problem Statement:

As a member of a team that is developing toys for JoyToys,

Inc., you have been assigned the task of creating a bike

module that accepts and displays bike details. Declare the Bike

class and its member functions. The member function that

accepts bike details should display the message AcceptingBike Details. Similarly, the member function to display bike

details on the screen should display the message Displaying

Bike Details.


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A variable is a location in the memory that has a name and

contains a value.

A variable is associated with a data type that defines the

type of data that can be stored in a variable.

Declaring Variables


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You can declare and initialize variables by using the

following syntax:

=;

Declaring and Initializing Variables


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Consider the followingexample of declaring andinitializing a variable:

int class_rank=2;

Declaring and Initializing Variables (Contd.)

Data Types in C#

Represents the kind of

data stored in a variable

C# provides you with

various built-in datatypes, such as:

char

int

float

double

bool

string


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Data Types in C#

Let us now understand the various data types with the help

of examples.


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Name

Marks

Age

Vowel

string

float

int

char

= Peter

= 83.56

= 23

= a

Data Types in C# (Contd.)


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Consider the following

example of declaring and

initializing a variable:

int class_rank=2;

Data types in C#

The following types of

data types are supported

by C#:

Value types

Num

Memory allocated

Variable declared and Initialized

int Num;

Num=5; 5

Data Types in C# (Contd.)

Memory Allocation in Value Type


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int class_rank=2;

Declaring and Initializing Variables

Data types in C#

The following types of

data types are supported

by C#:

Reference types

string Str=Hello;

Str

0 1 2 3 4

H E L L O

Address

Memory Allocation of the String Type Variable


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int class_rank=2;


Naming variables in C#

The following rules are used

for naming variables in C#:

Must begin with a letter or

an underscore Should not contain any

embedded spaces or

symbols

Must be unique

Can have any number ofcharacters

Keywords cannot be used

as variable names


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int class_rank=2;


Examples and non-examples

of Naming Variables

Name

#Score

Age

2Strank

Family_Size

Gender


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Consider the

following example of

declaring and


int class_rank=2;


Initializing Variables in C#

Specifies the value that

needs to be stored in a

variable. The value could be

an integer, a decimal, or a

character.


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To understand how to accept

value in a variable, let us

consider the following code

snippet:

int Number;

Number=

Convert.ToInt32(Console.Rea

dLine());

Accepting and Storing Values in Member Variables

Console.ReadLine()

Is used to accept input

from the user and store it

in the variable


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To understand how to accept

value in a variable, let us

consider the following code

snippet:

int Number;

Number=

Convert.ToInt32(Console.Rea

dLine());

Accepting and Storing Values in Member Variables(Contd.)

Convert.ToInt32()

Converts the value

entered by the user to

the int data type

Obj O i d i i C


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Let us know learn to write, compile, and execute a C#

program.

Writing and Executing a C# Program

Obj O i d P i U i C#


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A C# program can be written by using an editor like

Notepad. Consider the following code, which declares a

class Car and also creates an object MyCar of the same

class:

using System;

class Car

{

//Member variables

string Engine;

int NoOfWheels;

//Member functionsvoid AcceptDetails()

Creating a Sample C# Program

The using keyword is used to include

the namespaces in the program.

Comments are used to explain the

code and are represented by //

symbols.

Member variables are used to store

the data for a class.

Member functions are declared insidethe class that are used to perform a

specific task.

Obj t O i t d P i U i C#


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{

Console.WriteLine("Enter the Engine Model");

Engine = Console.ReadLine();

Console.WriteLine("Enter the number of Wheels");

NoOfWheels = Convert.ToInt32(Console.ReadLine());

}public void DisplayDetails()

{

Console.WriteLine("The Engine Model is:{0}",

Engine);

Console.WriteLine("The number of wheels are:{0}",

NoOfWheels);

}

}

Creating a Sample C# Program (Contd.)



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//Class used to instantiate the Car class

class ExecuteClass

{

public static void Main(string[] args)

{

Car MyCar = new Car();MyCar.AcceptDetails();

MyCar.DisplayDetails();

}

}

Creating a Sample C# Program (Contd.)

The Execute class is used as a class from

where the Car class can be instantiated.



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After writing the program in a Notepad, you need to compile

and execute it to get the desired output.

The compiler converts the source code that you write into

the machine code, which the computer can understand.

The following steps are needed to compile and execute aC# program.

1. Save the code written in the Notepad with an extension .cs.

2. To compile the code, you need to go to the Visual Studio

2005Command Prompt window. Select StartAllProgramsMicrosoft Visual Studio 2005Visual StudioToolsVisual Studio 2005 Command Prompt. The VisualStudio 2005 Command Prompt window is displayed to

compile the program.

3. In the Visual Studio 2005 Command Prompt window, move

to the location where the programs file is saved.

Compiling and Executing C# Program



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4. Compile the program file by using the following command:

csc ExecuteClass.cs

5. To execute the code, type the following in the command

prompt:

ExecuteClass.exe

Compiling and Executing C# Program (Contd.)



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Problem Statement:

David is the member of a team that is developing the

Automatic Ranking software for a tennis tournament. You have

been assigned the task of creating a program. The program

should accept the following details of a tennis player and

display it:Name, containing a maximum of 25 characters

Rank as an integer

Winning average as a decimal value

Help David to create the program.

Demo: Creating a C# Program

Object Oriented Programming Using C#


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In this session, you learned that:

According to the object-oriented approach, systems consist of

component objects that interact with each other.

An object is an entity that may have a physical boundary.

However, it should have the following characteristics:

State

Behavior

Identity

A class consists of a set of objects that share a common

structure and behavior.

If an object desires an action from another object, it sends amessage to that object.

The object that receives the message is called the receiver, and

the set of actions taken by the receiver constitutes the method.

Summary



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The features of the object-oriented approach are:

Realistic modeling

Reusability

Resilience to change

Existence as different forms

A model of a system is built in the stages of analysis, designand implementation.

The purpose of the model is to help developers understand the

reality that they are trying to imitate.

In C#, a class is created by using the keyword class. It is

identified by a name called the class name.The Console.WriteLine() method is used to display text on the

screen.

Main() is the first function which is executed in a C# program.

Summary (Contd.)



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Escape characters are used to display special characters such

as the newline character.

A variable is a named location in the memory, which contains a

specific value.

A datatype defines the type of data that can be stored in a

variable.The two types of data type are Value type and Reference type.

The ReadLine() method is used to accept inputs from the

user.

The using keyword is used to include the namespaces in the

program.A namespace contains a set of related classes.

Member variables are declared inside the class body.

Summary (Contd.)



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Comment entries are notes written by a programmer in the

code so that others reading that code can understand it better.

An object is an instance of a class.

The compiler software translates a program written in a

language like C# into the machine language.

Summary (Contd.)

01 iec t1s1 oops session 01

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