Foysal's Online School

Javascript Basics : Part 2 (Functions)

2011-11-11T23:27:00.001+06:00

Suppose I want to change the button color when it isclicked. And to do this task, I don’t want to send the page to the server. So,what should I do?

Well, HTML DOM has given us some events to work with. Wewill use one the events, Click event and put some code on its event.

The below code will change the button color if clicked onthat.

Now, if we want to add another button and apply samefunctionality with the click, the code will like below

But if you look closely, we are repeating the code. This isthe worst smell of the code smells. So, we should create a method and call that methodfrom the click event.

So, how do we create a function in Javascript? Its easy. As wedid before, we must add the ‘script’ tag first. Inside of this tag, we willwrite the function. In javascript, we must write the word ‘function’ before thename of the function. For example:

function MyFunctionName() {

}

Then we will call that function from the event. So, if werefactor the above html code, we will get the below

function ChangeColor() {

document.bgColor = "#ffaaff";

}

Total Code:

Please note that, we can write the functions anywhere in thepage inside of html tag. But it is good practice to put the function inside ofthe head tag.

We can pass parameter in javascript functions. In our aboveexample, we can pass the color code from the button tag to the function. The callingpart should be like this:

onclick="ChangeColor('#ffaaff')"

The function definition will be:

functionChangeColor(color) {

document.bgColor = color;

}

Total code:

We can also return from a javascript function. But unlike C#and other common languages, Javascript function don’t have any return type withits definition. We will just return the result at the end of the method.

Now, according to our above scenario, we can get ourrequired color using another function instead of passing the color code fromthe button tag.

So, we will have two functions. One will check and returnthe color code and the other function will be called from the button tag.

function GetColor() {

if(document.bgColor.toString() == "#ffaaff"){

return"#ffffff";

}

else if(document.bgColor.toString() == "#ffffff"){

return"#ffaaff";

}

return "#ffffff";

}

functionChangeColor() {

document.bgColor = GetColor();

}

Total code:

Quick Test

If we want to display square of a number, we will add script the calling part in the 'body' tag and return the square from a Javascript function. I hope you can do it. If you can't just let me know.

I will try to post about the events in my next blog post.

Javascript Basics : Part 1 (Hello world)

2011-11-09T22:51:00.001+06:00

Now a days, the most basic thing a web application developer must know is Javascript.So, what is javascript? Yes..you probably know Javascript is nothing to do with Java. Javascript is totally different with Java. In syntax, in semantic, in usage, in all aspects. So, Javascript is a scripting language which runs in browser. The browser software executes the script line by line, from top to bottom, and display you the output.

Now what you can guess, Javascript must be embedded in a HTML file and when the HTML codes are rendered/executed, Javascript codes get executed with those.If you want to let your browser know that you are writing a Javascript code, you must add some extra tags/codes with the statements. For example:

What you can see, at the above code, by the ‘document.write’ method, we are writing some text in the browser. But we need to add the 'script' tag having the type as javascript with it.
If the browser executes this line of code, we can view ‘Javascript is very easy’ text on the browser.
So, the total html code should be

To do this by yourself, follow the below steps:

1. Open notepad
2. Copy and paste the above html code (with Javascript)
3. Save the file as ‘FirstPage.html’
4. Close the file
5. Double click on your just created ‘Firstpage.html’ file
6. You should see the below output

Ok. so we made something which is running. Its amazing when we get something running.

In next post, we will talk about the javascript functions.

LINQ - The beginning

2011-09-27T22:20:00.000+06:00

Can not load 'crdb_adoplus.dll' solved by useLegacyV2RuntimeActivationPolicy

2011-09-15T00:46:00.000+06:00

In one of my current project, I am using visual studio 2010. I need to show report for some features. Well, everything was going smoothly before i installed my Windows 7 again in last week.
after installing visual studio 2010, I installed the crystal report executables provided by BusinessObjects .
then i ran my project and tried to open the report. But unfortunately it was showing the following error
"Could not load file or assembly 'file:///C:\Program files (x86)\Sap BusinessObjects\Crystal Reports For .Net Framework 4.0\Commom\Sap BusinessObjects Enterprise XI4.0\win32_x86\dotnet1\crdb_adoplus.dll' or one of its dependencies. The system cannot find the file specified."

In enlarged mode:

I have searched and found a solution. I just needed to put the useLegacyV2RuntimeActivationPolicy="true" into the tag under tag.

And guess what? The report is not displaying like below:

I am not sure why it is happening. I will write another blog post about it. Keep in touch. :)

How to change the Database Connection of LINQ to SQL Class

2011-07-25T02:27:00.000+06:00

Introduction

Its very common that couple of developers are working on a single project. Me and one of my friend are also working on a .NET project. We are using LINQ to SQL class to query on the database. This is a desktop Windows Form project and we are maintaining our code as dumbest way possible. That is, when i update on any part, i just mail him the file and he replaces the file. So far so good.

Problem statement

But when I sent him my project, he couldn't run the database queries. Because the connection string embed on the DataContext.dbml class was not changed. He couldn't find a good way to change the connection string value. So I was searching for a better solution, and at last I found it today.

Solution

1. Double click on the DBML file of your project.

2. Now right click on the work area of the DBML file (Start sign in the image)

3. Expand the connection property and check the Data Source value. in my case, it is 'Magicbox' since it is my machine's server name

4. If your server is not in mentioned, it means, you need to create another connection between your server and the DBML file. So, click on the 'New; displayed in the image

5. Put your server name or click on the combo box (the arrow sign)

6. If your server name is not displayed after clicking on the combo, please write the name by your own ( my server's name is not showing also)

7. Now click the database name combo box at the bottom side of the window. You will see the database names attached with your server

8. Select the database and click 'Test Connection' button. you will get a success message is connection succeed. Now close the success message and press OK button at the bottom of the page

9. Now if you click the connection combo again, you should see the just added database connection as the item of the combo

Conclusion:

We now just change the database connection value from the properties of the DBML file and working fine.

HTML Document Object Model

2011-07-09T23:54:00.000+06:00

What is it?
The HTML DOM defines a standard way for accessing and manipulating HTML documents. The DOM presents an HTML document as a tree-structure.
In the DOM, everything in an HTML document is a node.
The DOM says:

The entire document is a document node
Every HTML element is an element node
The text in the HTML elements are text nodes
Every HTML attribute is an attribute node
Comments are comment nodes

Example Node tree:

From the HTML above:

The < html > node has no parent node; it is the root node
The parent node of the < head > and < body > nodes is the < html > node
The parent node of the "Hello world!" text node is the < p > node

and:

The < html > node has two child nodes; < head > and < body >
The < head > node has one child node; the < title > node
The < title > node also has one child node; the text node "DOM Tutorial"
The < h1 > and < p > nodes are siblings, and both child nodes of < body >

It has some properties and methods as well.
Some DOM properties:

x.innerHTML - the text value of x
x.nodeName - the name of x
x.nodeValue - the value of x
x.parentNode - the parent node of x
x.childNodes - the child nodes of x
x.attributes - the attributes nodes of x

Note: In the list above, x is a node object (HTML element).
Some DOM methods:

x.getElementById(id) - get the element with a specified id
x.getElementsByTagName(name) - get all elements with a specified tag name
x.appendChild(node) - insert a child node to x
x.removeChild(node) - remove a child node from x

Note: In the list above, x is a node object (HTML element).
Example:

DOM Methods details:
getElementById(parameter): gets the element which has the id equals to the parameter
getElementsByTagName(parameter): gets the element which is the html tag equals to the parameter
Working with DOM code snippets:
document.body.bgColor="lavender"; //changes the document's background color
document.getElementById("p1").innerHTML="New text!"; // replaces the text of all p1 id element with "New text"
< input type="button" onmouseover="document.body.bgColor='green'" onclick="document.body.bgColor='lavender';" value="Change background color" / >
.style : this property indicates you can also work with the element's style values
Events:
Examples of events:

A mouse click
A web page or an image loading
Mousing over a hot spot on the web page
Selecting an input box in an HTML form
Submitting an HTML form
A keystroke

Example: < input type="text" id="email" onchange="checkEmail()" / >
For more: visit W3Schools

ASP.NET MVC Custom Routing Problem (Solved by Areas)

2011-03-02T15:47:00.000+06:00

ASP.NET MVC 3 has a built in feature for sub folders. That is called Areas (thanks @Morten for let me know the word).
But after finishing the MSDN Walkthrough for Areas, I was still unable to run the web application. The error was showing Configuration errors.
Then I searched and found that, the Web.config files in the sub folders shouldn't contain application specific properties.
So, I removed those properties from the Web.config files. Then I was able to run. But there were some runtime errors when I wanted to navigate to my sub folder/area views. The error was "Could not load type ‘System.Web.Mvc.ViewPage<..<>’" when I click on the links for the views of the Areas folder.
Then I again searched and found helpful this post. And then my application successfully run and I can navigate all of the pages.

Introducing Object Oriented Concept

2010-11-29T00:01:00.001+06:00

In this section we will learn about 'How to think in Object Oriented way'.

Objectives

After completing this unit we should be able to:

* Think the real world in object oriented way

* Understand what really object and class means

* Describe what are attributes and responsibilities of an object.

Topics

In this unit, we will learn about the following topics:

* What's wrong with starting of Object Oriented Programming

* Philosophy of OOP

* Mapping Object Oriented Thoughts to Object Oriented Programming

What's wrong with starting of Object Oriented Programming

Unfortunately most of us start Object Oriented Programming (OOP) jumping into a language book like C++, Java or C# etc. But it's not a good start at all. Starting with OOP language book, we may learn writing package/namespace, class, object, interface, etc. But writing class, interface, object etc. does not guarantee good software design. OOP is totally useless if we can't use this concept for good software design. So, what should we know first? What should we know before starting with an OOP book?

First of all we should know: what's an object and how to think in OO (Object Oriented) way.

Philosophy of OOP

Yes, Starting of Object Oriented Programming is of course the concept of object.

And this concept is really simple. Ok, I am starting to speak about it. Before starting, I am requesting you to forget everything about programming, database design, software design i.e. all kinds of software engineering and programming language details for some couple of minutes (not forever!!).

Everything can be an object

Look around you, what we see, ALL ARE OBJECTS. We see computer, chair, table, pen, air cooler, carpet etc, all these are objects. Why they are object? Pretty simple, they have some related attributes and some related activities. How? Ok, just think about computer, it has processor, RAM, hard drive, keyboard, mouse, etc. All these are the attributes of computer. Now, what're the activities of a computer? It has a lot: it runs antivirus program, displays information, accepts requests and executes these properly. All these are the activities of computer. So, computer is an object. In the same way, we will get the attributes and activities of chair, table, etc. So, to be an object, something should have attributes and/or should have activities. Finally, from the above discussion, we can draw a conclusion:

Everything can be an object.

How it is possible? Is it possible that any event, like war or raining, singing, thinking etc (which is not visible) can be object? The answer is YES. These can be objects also. Think, raining has attributes: is it drizzling or "cats and dogs"? Singing can be an object if we consider, in which frequency-range it is sung?

'Name' – is it an attribute or an object? Actually, it is totally depend on problem domain. See, if you are thinking about a banking solution then customer 'Name' will be an attribute of customer. But if it a business from where you can purchase the 'Name' of your new-born baby then 'Name' will be an object to this business. Because 'Name' has meaning, length, type etc.

Note: In some OOP books, authors may use data instead attribute and responsibility (I personally think it is better term) instead of activity.

Object's data and responsibility depend on problem domain

If I tell you and your friend to find out the data and activity of customer object, suppose, you get customer with name, email, phone attributes and purchase, bargain activities. At the same time your friend may get customer with first name, middle name, last name, gender, credit card attributes and open account activity.

Why it happens? It happens because you and your friend were on different platform with different point of view. You think about the customer of a grocery store whereas your friend thinks about the customer of a bank. But both of you are right.

So, object and its data, responsibility everything totally depends on problem domain.

What is class?

Class is the blue print of object. Suppose, I say Johnny, Mary and Russell are students. Here, Johnny, Mary and Russell are objects and Student is the class. More specifically, Student is the class with name attributes and there are three student objects whose names are Johnny, Mary and Russell.

Walkthrough 1: Mapping Object Oriented Thoughts to Object Oriented Programming

To make our conception more clear, now we will try to make a small application. Of course, we will try it Object Oriented way.

Let's start. Suppose our considering problem domain as follows:

"………User wants to get full name and reverse full name providing first name, middle name and last name of a person."

We will identify the objects first. Here, we will get 'Person' object as follows:

Person

Has first name

Has middle name

Has last name

Can tell its full name

Can tell its reverse name

Now we will implement this in C# (VS 2008, DotNet 3.5), an OOP language.

Steps:

Start Microsoft Visual Studio 2008
Click File>New>Project

we will see the following window. Select 'Class Library' template, give a meaningful name and select your preferable location.

Click 'Ok' Button
In Solution Explorer, we will see Class1.cs file. Delete this file.
Select project (not solution) OOPWalkThrough1 and Click right button. Then Click on Add>Class from the popup menu. We will get following window.

Remind we have found an object, 'Person' in our problem domain. Here we will give 'Person.cs' in Name as a file name.
Click 'Add' button and we will see the following code

using System;

namespace OOPWalkThrough1
{

class
Person
{
}
}

Here, Person is a class.
Now update the Person class as follows:

namespace OOPWalkThrough1

{

class
Person

{

public
string firstName;

public
string middleName;

public
string lastName;

public
string GetMyFullName()

{

return firstName + " " + middleName + " " + lastName;

}

public
string GetMyReverseName()

{

string reverseName = "";

string fullName = GetMyFullName();

for (int index = fullName.Length - 1; index >= 0; index--)

{

reverseName += fullName[index];

}

return reverseName;

}

Have a look inside the Person class. Compare the identified object (Person) with the Person class.

We see data of Person are represented by attributes and responsibilities are represented by methods. So any object creates from Person class will represent our domain object, Person.

Now add another class in this project. Here file name will be EntryPoint.cs (or any meaningful name you like) and write Main() method inside this class as follows:

Here, we will create a Person object, personObj from Person class using the following line:

Person personObj = new
Person();

Then assign some data to the attributes of personObj as follows:

personObj.firstName = "James";

personObj.middleName = "Lucas";

personObj.lastName = "Scott";

Finally, ask personObj to tell it's full name and reversed-name and get it:

string fullName = personObj.GetMyFullName();

string reverseName = personObj.GetMyReverseName();

To make the project executable, we need to change the project properties. Select the project, click right button, select Properties from pop-up menu; we will get the following tab to change project properties.

Select Output Type as Console Application and Startup object as OOPWalkThrough1.EntryPoint.

Run the application and we will the output:

To take input from user we need to change the Main() method. Replace these three lines:

personObj.firstName = "James";

personObj.middleName = "Lucas";

personObj.lastName = "Scott";

with the following three lines

personObj.firstName = Console.ReadLine();

personObj.middleName = Console.ReadLine();

personObj.lastName = Console.ReadLine();

Important Note

Here, to keep the example simple, I've violated encapsulation (keep the data public) principle.

To solve a problem, mapping a domain object directly to software object sometimes may not be a good solution.

Walkthrough 2: Convert the application of Walkthrough 1 to Windows application.

Open from the project, OOPWalkthrough1 from Examples & WalkThroughs\OOPWalkThrough1 location.
Add a new Form class in your project (Right-click on project, click Add>Windows Form). In name textbox, type PersonInformationUI.cs and click Add button. Then you will see a windows form.
Design the windows form as following UI and give the appropriate name of each control.

Write the following code inside Show button_click event:

Person personObject = new
Person();

personObject.firstName = firstNameTextBox.Text;

personObject.middleName = middleNameTextBox.Text;

personObject.lastName = lastNameTextBox.Text;

fullNameTextBox.Text = personObject.GetMyFullName();

reverseNameTextBox.Text = personObject.GetMyReverseName();

Change your Main() method of EntryPoint class with following code:

PersonInformationUI personInformationUIObj =

new
PersonInformationUI();

Application.Run(personInformationUIObj);

Right-Click on project of solution explorer. You will see a popup and click properties. Select Application Tab, Change output type to Windows Application.
Run the application and see it works.

Practice 1: Application for bank account transaction

User story:

"As a customer

I want to create an account and wants to do transaction (deposit and withdraw) on it."

See the UI prototyping:

When report button is clicked, information will be displayed as follows:

Run BankAccountOperation.exe from 3.1 Basic Concept\Practices for better understanding.

Code Smells : The Manual [Part 1]

2010-02-14T11:10:00.000+06:00

Code Smells

By the definition i found in

Wikipedia, code smell is: "In computer programming, code smell is any symptom in the source code of a program that possibly indicates a deeper problem."

We do mistakes while we code. Its very certain. Some of us know about the smell while we code, others don't. But if someone just avoid the common smells in coding, his/her code will be increased a lot in quality. So, to write a quality code, we must know what are the code smells and we MUST avoid it.

My personal opinion is, don't be a procrastinator in coding. Remove the smells after a single method or at least after completing a feature.

In below these are the code smells that a beginner in coding should know. I will add more explanation to each of the smells in future.

[Black circled point is the name of the smell and while circled point is the solution to remove the smell from your code.]

Inappropriate naming

rename it

Comments

extract method
rename method
introduce assertion

Dead code

delete

Duplicated code

extract method
pull up field
form template method
substitute algorithm

Primitive obsession

extract class
replace data value with object
replace type code with class
introduce parameter object
replace array with object

Large class

extract class
replace type code with class/subclass
replace type code with state/strategy
replace conditional with polymorphism
extract interface
duplicate observer data

Lazy class

inline class
collapse hierarchy

Long method

extract method
replace temp with query
introduce parameter object
preserve whole object
replace method with method object
decompose conditional

Long parameter list

introduce parameter object
replace parameter with method
preserve whole object

Switch statements

replace type code with polymorphism
replace type code with state/ strategy
replace parameter with explicit methods
introduce null object

Speculative generality

collapse hierarchy
inline class
remove parameter
rename method

Feature envy

move field
move method
extract method

Temporary field

extract method

Implementing database concepts to develop an application in agile approach : Part 1.3 (Coding)

2009-12-03T23:45:00.001+07:00

Hello everyone. In my last two post, i have showed how to create a database according to the user's story. In this post, i will show you how to develop/code the application to access the database. I am assuming you all know how to create an application in visual studio 2008 and run it. So, i am not discussing the steps of creating a windows application in Visual Studio IDE. If you have problem in this, please find my other posts in where i have discussed about creating the desktop application in C#. Ok. Lets start.

Open Visual Studio 2008
Create a desktop application named ‘ABCUniversityApplication’
Create a windows form named ‘StudentEntryUI’
We have found an object student from our problem domain. So create a class Student which have name, email address, address and phone number as its data. Create a constructor to assign these values when creating a new student object.

public class Student

{

private string name;

private string emailAddress;

private string address;

private string phoneNumber;

public Student(string name,string emailAddress, string address, string phoneNumber)

{

this.name = name;

this.emailAddress = emailAddress;

this.address = address;

this.phoneNumber = phoneNumber;

        }

   public string Name
   {
   get { return name; }
   }

   public string EmailAddress
   {
   get { return emailAddress; }
   }

   public string Address
   {
   get { return address; }
   }

   public string PhoneNumber
   {
   get { return phoneNumber; }
   }

   }

5. Now create a user interface like the given figure

6. Now take a note. Your ‘Student’ class holds the student data. Your UI class takes data from user. So you need a class which will check the validity of the data input by the user. That’s why you need a manager class which will perform different works related with the student object. Create a ‘StudentManager’ class which will take data from UI and pass it to another class for saving.

public class StudentManager

{

public void SaveStudentManager(Student student)

{

StudentGateway studentGateway=new StudentGateway();

studentGateway.SaveStudentIntoDatabase(student);

}

}

7. Create the ‘StudentGateway’ class for saving the student object into the database.

To do so, you need to use some built in class of C#.

a. Create a connection string which will be used as a parameter to establish a connection with the database

string connectionString = @"server=Magicbox\SQLEXPRESS; Integrated Security = SSPI; database = ABCUniversityDatabase";

b. To create a connection with the database, you need to use SqlConnection class. To use it, you have to import system’s SqlClient directive into your code

c. Create an object of that class.

SqlConnection connection = new SqlConnection(connectionString);

d. Open the connection of the databse.

connection.Open();

e. Now create the insert query string for execution to save the data into the database.

Since your Student class doesn’t have the get properties of the data, change your Student class adding the get part for each of the data.

string insertQueryString =

@"INSERT INTO t_Student VALUES ('" +student.Name + @"','" +student.EmailAddress + @"','" +student.Address + @"','" +student.PhoneNumber + @"')";

f. Now you need a SqlCommand object to execute the query you have built to save the data

SqlCommand command = new SqlCommand(insertQueryString, connection);

g. Now execute the command

command.ExecuteNonQuery();

h. So at the end, your StudentGateway class will have the following code snippet

public class StudentGateway

{

public void SaveStudentIntoDatabase(Student student)

{

string connectionString = @"server=Magicbox\SQLEXPRESS; Integrated Security = SSPI; database = ABCUniversityDatabase";

SqlConnection connection = new SqlConnection(connectionString);

connection.Open();

string insertQueryString =

@"INSERT INTO t_Student VALUES (

'" +student.Name + @"',

'" +student.EmailAddress + @"',

'" +student.Address + @"',

'" +student.PhoneNumber + @"'

)";

SqlCommand command = new SqlCommand(insertQueryString, connection);

command.ExecuteNonQuery();

}

Now go back to your UI class. Write down the following code into your saveButton method block

private void saveButton_Click(object sender, EventArgs e)

{

Student student=new Student(nameTextBox.Text,emailAddressTextBox.Text,

addressTextBox.Text,phoneNumberTextBox.Text);

StudentManager studentManager = new StudentManager();

studentManager.SaveStudentManager(student);

MessageBox.Show(student.Name+"'s information is saved into database");

nameTextBox.Text = "";

emailAddressTextBox.Text = "";

addressTextBox.Text = "";

phoneNumberTextBox.Text = "";

}

Now build the application and run it. Enter the data given like the following figure and click on the save button

If the data is saved, the messagebox will appear showing you the success of the saving of your data.
Now go to your Sql Server Management Studio Express and right click on t_Student table
Click ‘Open Table’ option to check whether our data is really saved or not
You will see the following figure

Thus we have saved a sample data into the database through an application.

Implementing database concepts to develop an application in agile approach : Part 1.2 (Database Server)

2009-11-18T13:05:00.001+07:00

Hello everyone. In my last post, i have showed how to create a table schema from real time problem domain, which is now we called as user story. But to work on a database, we need to create tables in a database server. Since i am working on .NET Platform, i am using Microsoft's SQL Server 2005.

Installing Microsoft SQL Server 2005:

This server is automatically installed when we install Visual Studio 2008. Or you can download the server file from http://www.microsoft.com/Sqlserver/2005/en/us/express.aspx.

Installing Microsoft SQL Server 2005 Management Studio Express:

To working on the SQL Server, you need to install a management tool. You can download this from http://www.microsoft.com/downloads/details.aspx?familyid=C243A5AE-4BD1-4E3D-94B8-5A0F62BF7796&displaylang=en this location.

OK. Now we are ready to work on the SQL Server.

When you lunch the management studio express, the following window will appear.

Figure 1: SQL Server Management Studio Express

I am giving you the short description of the SQL Server Management Studio Express opening window. Please Google yourself if you want to know more on this topics.

Server name:

In your computer, you may have several instances on of sql server 2005, or different versions of sql server like as 2005, 2008 etc. you will give them a specific name to work with it.
In this case, MAGICBOX is the server name and SQLEXPRESS is the instance name of the sql server 2005 on which we are currently working on.

Authentication:
Sql server provides you couple of types of authentication. In Windows Authentication, server assumes since you logged into the machine, you are authenticated to access on the server. But if you use the other type (SQL Server Authentication), you have to enter the credentials of User name and the Password field of that server instance.

Now we will create the table in database.

Walkthrough 1: Creating ‘t_Student’ table using SQL Server Management Studio Express
Steps:
1. Go to: StartMicrosoft SQL Server 2005SQL Server Management Studio Express
2. The following window will appear

Figure 2: Opening Window of Management Studio

3. Click the ‘Connect’ button
4. There are several nodes you will find on which you can work with. Each of the nodes explains itself.

Figure 3: Explorer of Management Studio

5. Right click on the ‘Databases’ node

6. Click on ‘New Database’
7. Enter the database name meaningful. For our user requirement, we will enter ‘ABCUniversityDatabase’ as the name.
8. Click on the button given in the following figure to select the destination path of the database files

Figure 4: Select the Destination Path

9. Click ‘OK’

10. You will find the following figure on your screen

Figure 5: Newly Created Database

11. Check your HDD file location to check the database file

Figure 6: Files created in your hard disk

12. Now expand the ‘ABCUniversityDatabase’ on your management studio express

13. Right click on the ‘Tables’ node
14. Click on ‘New Table’ option
15. Enter the column names given in the following figure

Figure 7: Column Definition of student's table

16. Click on save option and enter the table name as ‘t_Student’

17. Now expand the ‘Tables’ node from Object Explorer window
18. You will find your just created table in here

Figure 8: Columns Viewed in Explorer

Thus you have created a table (t_Student) in your database (ABCUniversityDatabase) to store data (information of studetns). :)

In my next post i will show you how to create the application in C#, which will take the information from the user and store it in the table.

Happy coding.

Implementing database concepts to develop an application in agile approach : Part 1.1 (Database Concept)

2009-11-17T20:35:00.000+07:00

Waterfall vs Agile:
Most of the developers in the world start making their software in the traditional way. Traditional means first they gather most of the requirements of the client and then start designing the database where the data will be stored. After designing the database, which is called Entity-Relationship Diagram (ERD), they start coding. This approach is called waterfall .
This is a very inefficient approach and it is turning obsolete day by day.
New types of thinking and implementations are coming one by one to make a software robust and easily maintainable. The most popular thinking approach now a days is. AGILE
The main part of agile is to start the working without waiting for the whole requirement of the client and evolve the application on the requirement of the client [Details] .
In agile, we don't use 'Requirement' types of word. We rather use 'User Story' as the specification of the software given by the client. I have used a traditional conversation process as the specification of the software.

I am assuming you are familiar with ERD, Basic Programming and you have sound concept on OOP.
If you don't have much confidence on OOP part, i prefer you to go http://tiemoon.blogspot.com here for the primary OOP concept.

Ok. Lets start developing an application for 'ABC University'.

The technical officer of 'ABC University' is Mr. X. Last month he came to me and talked with me about a software for his university.
The conversation was similar to the following one.
[User story:]
Mr. X: “I am the technical officer of ABC University. We admit a lot of students in every semester. So entry down those students is very tough for us in pen and paper. I want to store the information in a computer”
Me: “What data do you want to store for a particular student?”
Mr. X: “Well. I want to store a student’s name, email address, address and phone number”
Me: “Ok. Fair enough. I am going to start developing the software for you”

Entity:
The thing which can be uniquely identified and stored to database is called en entity. It is like an object in OOP concept. The collection of the entity which shares the common characteristics is called the Entity Sets. We can map this concept in OOP as Class.

Analysis:
So in our user story, we can identify Student as an object. So it is an entity and it is the thing that is to be stored.

Notation:
We use a rectangle for expressing an entity in ERD.

Result:

Figure 1: Entity

Attribute:
The information we want to store about our entity is called attribute. Any data that will qualify, identify, classify or express the state of entity is called attributes. It can be mapped like the data of an object in OOP.

Analysis:
Since Student is our primary entity, we start analyze its attributes which holds the information of a particular student. And we found a student’s name, email address, address and phone number those are going to be stored for a particular entity.

Notation:
We use an oval to denote an attribute of an entity.

Result:

Figure 2: Entity and Attributes

NB: Each of the entity must have a table containing its attribute as the column name.

Naming convention that i will follow through my posts:

Each of the entity will be in a Noun form. A table will be started with the charactre ‘t’ followed by a underscore ‘_’ and then the entity name. eg: t_Student
A column will be started with it’s entity name of camel case and then an underscore and then it’s original name. eg: student_Name

So, if we sketch our table structure as a schema, then according to our user story, we will find the table schema as,

t_Student ( student_Name, student_EmailAddress, student_Address, student_Phone)

The table schema is been created. Now we will create it in our database server. I describe it in my next post (1.2)

Introduction to C# : A hands on approach (Part 2)

2009-11-05T15:45:00.000+07:00

Introduction to C#: Day 2

In this lesson you will be familiar with different types of C# syntax some conceptual things.

Objectives:

After completing this unit you should have a clear concept on:

* Data types

* Expressions

* Conditional statements

* Iteration statements

* Methods in C#

* Enum

You will be able to create applications using the following controls:

* ComboBox

* GridVeiw

* ListView etc.

Topics

In this lesson you will learn about the following topics

* Data types

* Data types conversions

* Data type: String

* Data type: Constant

* Expressions

* Operators

* Conditional statements

* Switch

* Iteration statements

* Enum

Data types:

When we instruct a machine to execute some operation, the machine changes the high level language (which we are sending) into machine code (sequence of 1s and 0s).

The instruction we are sending also contains data on which the operation will be executed.

But not all data should contain the same amount of memory nor do the same types of operation. So, different sets of data have different size and perform different types of operation. And they are not interpreted in the same way.

So, a instructor (programmer) has to tell the system before-hand, the type of number or characters he is using in the instruction. These type are called Data Types. There are many data types in C# language. A programmer has to use appropriate data types as per his requirement.

There are 2 types of Data Type. They are

i. Predefined Data Types

ii. User defined Data Types

Predefined Data Types:

This kind of data types are created by the C# creator programmers (Microsoft Programmers). They define the characteristics of the data types and also define the set of allowed activities a specific data type can do. Different types of predefined data types allocated different amount of memory and performs different types of operation.

The following data table lists the predefined data types and describes the data that they are designed to store.

Type Name	Definition	Byte
Byte	Integer (0 to 255)	1
Sbyte	Integer(-127 to 128)	1
Short	Integer (-32768 to 32767)	2
Ushort	Integer (0 to 65535)	2
Int	Integer (-2147483648 to -2147483648)	4
Uint	Integer (0 to 4294967295)	4
Long	Integer (-9223372036854775808 to -9223372036854775808)	8
Ulong	Integer (0 to 18446744073709551615)	8
Bool	Boolean value(true or false)	1
Float	Single-precision floating point value	4
Double	Double-precision floating point value	8
Decimal	Precise decimal value to 28 significant digits	12
Object	Base type of all other types	N/A
Char	Single Unicode character	2
String	An unlimited sequence of Unicode characters	N/A

User defined data types:

User defined data types are composed of different combination of predefined data types. Sometimes a user defined data type contains another user defined data type in it. A user defined data type can also perform some operations and the definition of the operation will be stated into the type definition.

Working with data types:

To use a data in our program, we have to follow some specified way and use some specific keywords that are defined by the language creators.

a. Declaration:

Declaration is something like allocating a memory space for a specific data and gives the memory address a name by which the programmer can operate on that data later. It is linking of a memory location to a data. The name of the memory location is called Variable.

Example: int count;

b. Initialization:

Initialization is the next step of declaring of a variable. In initialization, valid data is inserted into the variable memory location. Valid data means the allowed types of data that the memory location can contain.

Example: int count = 10;

c. Literals:

Literals are a single character used at the end of a data. It is used to put data into a memory location that is normally invalid for that memory location.

Example: decimal priceWithVat = 123.123M;

Walkthrough 1: Working with data types

To make the data type clear, we will practice some works on data types.

Steps:

1. Create a new console application

2. Declare a variable of Integer type

3. Initialize it with some data

4. Display the variable in the console.

5. Now declare a float type variable and initialize it

6. Build it

7. You will find an error saying “Literal of type double cannot be implicitly converted to type 'float'; use an 'F' suffix to create a literal of this type”

8. Put a character ‘F’ or ‘f’ at the end of the data of the initialization statement.

float variable = 12.2f;

9. Build it

10. Run it

Data Type: String

As stated above, a string variable contains a sequence of alphanumeric characters. We can declare a string variable like other types of variable.

Example:

string name; // Declaration

string firstName = "Foyzul"; //Initialization

Escape characters:

Escape characters are used when we want to set a run time meaning of a part of a string.

Example:

string greetings = "Hello everyone.\nWelcome to BASIS.";

Verbatim characters:

A verbatim string is a string that is interpreted by the compiler exactly as it is written, which means that even if the string spans multiple lines or includes escape characters, these are not interpreted by the compiler and they are included with the output. The only exception is the quotation mark character, which must be escaped so that the compiler can recognize where the string ends.

Example:

string address = @"C:\Software\Books\Beginning”;

As you can see, verbatim is indicated with an ‘@’ sign at the beginning of a string.

If you want to use a quotation mark inside a verbatim string, you must escape it by using another set of quotation marks.

Example:

string greetings = @"""Hello everyone"".said the trainer.";

Walkthrough 2: Working with String types

Steps:

1. Create a console application

2. Declare a string variable and initialize it by your name

3. Display the variable in console

4. Build the solution and run it

5. Now change the value of the variable using "Hello everyone.\nWelcome to BASIS."

6. Build it and run it

7. Change the value of the string with the address of your project directory using verbatim

Data Type: Constants

A constant is a variable whose value remains constant. Constants are useful in situations where the value that you are using has meaning and is a fixed number, such as pi, the radius of the earth, or a tax rate.

Example:

const int radiusOfEarth = 6378;

As you can see, constant variable starts with the keyword ‘const’ at the declaration, or initialization.

Walkthrough 3: Working with Constant

Steps:

1. Create a console application

2. Declare a constant integer type variable and initialize it

3. Display the variable in console

4. Build it and run the application

Data Type Conversions:

Sometimes we have to change the data that we are using. Sometimes this change may change the value of the data or sometimes it just changes the memory space allocated by that data. This change is called data type conversion.

Data type is converted in 2 ways. They are:

a. Implicit conversion

b. Explicit conversion

They are described below.

Implicit conversion:

An implicit conversion converts data automatically without losing any data. Normally, data types can implicitly converted into the data types those contain more memory space.

Example:

short firstNumber = 65;

long secondNumber = firstNumber;

Explicit conversion:

An explicit conversion convert data that are automatically can’t be converted. It may converts data from bigger size to smaller size or converts data from one type into totally different type.

Example:

short firstNumber = 65; //Initialization

long secondNumber = firstNumber; //Implicit conversion

short thirdNumber = (short)secondNumber; //Explicit conversion

Console.WriteLine(thirdNumber); //outputs 65

char a = (char)firstNumber; //Explicit conversion

Console.WriteLine(a); //outputs A

We can use some built in functions those are provided with C#.

a. Convert class:

A convert class contains numerous method those can change one data type into another type. It is another implementation of explicit conversion.

Example:

int number = 65; //Initialization

char character = Convert.ToChar(number); //Conversion using System's Class

Console.WriteLine(character); //Output: A

b. ToString() method:

A ToString() method converts any kind of data type into String type. It doesn’t change the internal value of that data.

Example:

char character = Convert.ToChar(65); //Conversion using System's Class

string numberString = (65).ToString();

Console.WriteLine(character); //Output: A

Console.WriteLine(numberString); //Output(value is in String form): 65

Figure: A Memory location

Walkthrough 4: Working with data conversion

To make the conversion more clear, we will go through a walkthrough now.

Steps:

1. Create a desktop application

2. Design a user interface given below

3. Select the last textbox and change its Readonly property to True

4. Double click on the button

5. Write down the following code into the button click event block

int firstNumber = Convert.ToInt32(firstNumberTextBox.Text);

int secondNumber = Convert.ToInt32(secondNumberTextBox.Text);

int sum = firstNumber + secondNumber;

sumTextBox.Text = sum.ToString();

6. Build the application and run it

Expressions:

An expression is a sequence of operators and operands. An operator is a concise symbol that indicates the action that you want to occur in your expression.

An operand is the value on which an operation is performed.

An operator is specifically designed to produce a new value from the value that is being operated on.

Example:

Conditional operator: &&,||

Mathematical operator: +

Conditional statements:

A conditional statement allows you to control the flow of your application by selecting the statement that is executed, based on the value of a Boolean expression.

Syntax:

a. If(boolean-expression) statement

b. If(boolean-expression) statement1

else statement2

c. If(boolean-expression) statement1

else if(boolean-expression) statement2

else statement3

Example:

bool condition;

if (condition == true)

{

Console.WriteLine("condition is true");

}

else

if (condition == false)

{

Console.WriteLine("condition is false");

}

else

{

Console.WriteLine("unknown valueA+");

}

d. If((boolean-expression) operator (boolean-expression)) statement

Example:

if (scoreOutOfHundred >= 60 && scoreOutOfHundred < 80)

{

return "A+";

}

e. (boolean-expression) ? (statement1) : (statement2)

Example:

bool value = true;

Console.WriteLine(value ? "True Value" : "False Value");

Walkthrough 5: Working with conditional statements

Steps:

1. Create a desktop application

2. Design the user interface like the following figure

3. Double click on the button

4. Write down the code snippet in the block

string planetName=planetNameComboBox.Text;

if(planetName=="Planet")

{

MessageBox.Show("It is in 3rd position");

}

if(planetName=="Saturn")

{

MessageBox.Show("It is in 6th position");

}

if(planetName=="Mars")

{

MessageBox.Show("It is in 4th position");

}

5. Build the solution and run it

Iteration Statements:

C# provides several looping mechanisms, which enable you to execute a block of code repeatedly until a certain condition is met. In each case, a statement is executed until a Boolean expression returns true. By using these looping mechanisms, you can avoid typing the same line of code over and over.

a. For loop:

A for loop must have 3 basic parameters. It must have a loop initializer value, a loop ending value and also an increment/decrement operator. These 3 types of value can be written in any part of the for loop block. But generally, these are written in the heading part of the loop.

Example:

for (int count = 0; count < endingValue; count++)

{

sum += count;

}

b. While loop:

While loop first checks a boolean expression and then enters into the code block. This loop runs until that expression turns into false.

Example:

while (condition == true)

{

sum += count++; ;

if (count > 50)

{

condition = false;

}

c. Do-While loop:

Do while loop first executes the whole code block one time and then checks the boolean expression. If the expression is false, this loop quit execution and go to the next statements. Otherwise, it runs until it finds the boolean expression false.

Example:

{

sum += count++;

}while (count < 10);

Keywords:

Continue:

To continue the loop operation without executing the rest of the statements on the block, continue keyword is used.

Break:

Break keyword is used to break the loop.

Example:

for (int count = 0; count < MAXIMUM_VALUE; count++)

{

if (count == expectedValue)

{

break;

}

else

{

continue;

}

Walkthrough 6: Working with iteration statements

Steps:

1. Create a desktop application

2. Design the user interface like the following figure

3. Double click on the button and write the code snippet given below

int itemNumber = Convert.ToInt32(numberTextBox.Text);

for (int count = 1; count <= itemNumber; count++)

{

numberListView.Items.Add(count.ToString());

}

4. Build the solution and run it

[Note: I assumed all of my readers are Computer Science Graduate so that I haven’t made the theoritical parts more lengthy.]

Introduction to C# : A hands on approach

2009-10-24T00:21:00.002+07:00

In this lesson you will be familiar with C# applications.

Objectives

After completing this unit you should have a clear concept on:

* Visual Studio 2008

* Anatomy of a C# program

* Visual Studio Templates

* Console application

* Desktop application

You should be able to create:

* Console application

* Desktop application

Topics

In this lesson, you will learn about the following topics:

* Visual Studio

* Templates

* C# program structure

* Console applications

* Desktop applications

Visual Studio

Microsoft Visual Studio is an Integrated Development Environment (IDE) created by Microsoft Corporation for Windows Application Development. This IDE is used to develop console and graphical user interface applications run able only in Windows Platform.

Visual Studio 2008 is one of the versions of Visual Studio. Some other versions are Visual Studio 2005 or Visual Studio 2010 or Visual Studio Team System.

Visual Studio provides some features to its users. Some of these are:

· Code editing

· Debugging the code

· Designing the User Interface

· Some helping tools

· Extensibility

Visual Studio has some built in compilers integrated in it. The main languages are C# and Visual Basic. But one can create any application in another language such as J#, C++ etc.

Templates

Visual studio project and item templates provide reusable and customizable project and item stubs that accelerates the development process, removing the need to create new projects and items from scratch.

Depending on the instance of the Visual Studio, generally there are 2 types of templates we can see. They are:

· Project templates

§ Windows

§ Web

§ Smart Device

§ Office

§ Database

§ Reporting

§ Test

§ WCF

§ Workflow

· Item templates

§ General

§ Web

§ Script

Walkthrough 1: Visual Studio Project Template Familiarization

To make the project templates more clear, now we will view some templates of Visual Studio 2008.

Steps:

Start Microsoft Visual Studio 2008
Click File>New>Project

You will see the following window.

Figure: Project Template

Walkthrough 2: Visual Studio Item Template Familiarization

To make the item templates more clear, we will now view some item templates of Visual Studio 2008.

Steps:

Start Microsoft Visual Studio 2008
Click File>New>File

You will see the following window.

Figure: Item Template

C# Program Structure

Class library:

Like all other programming language, C# also follows some rules. At first, a sample program needs some system library classes. These libraries help the compiler to compile the code.

For example:

using System.Text;

If this is not written at the beginning of a class structure, one can’t use the regular expression functionalities under that class.

Namespace:

A project can have multiple files. To organize these classes, multiple folders can be created. The conceptual hierarchy is called the namespace.

For example:

namespace AnatomyOfCSharpClass

This is a sample namespace of a project.

Main Method:

Main method is the entry point of any kind of high level language. C# is not indifferent from that. A C# project must have a main() method. The code written for a main method is:

static void Main(string[] args)

Console Applications

A console application is a computer program designed to be used via a text-only computer interface, such as a text terminal, the command line interface of some operating systems (Unix, DOS, etc.) or the text-based interface included with some Graphical User Interface (GUI) operating systems, such as the Win32 console in Microsoft Windows.

A user typically interacts with a console application using only a keyboard and display screen, as opposed to GUI applications, which normally require the use of a mouse or other pointing device. Many console applications such as command line interpreters are command line tools, but numerous Text User Interface (TUI) programs also exist.

Walkthrough 3: Creating a console application

To make the discussion more clear, we will now create a very small console application. This application will show “Hello World” into the console.

Steps:

Start Microsoft Visual Studio 2008
Click File>New>Project

You will see the following window.

Figure: New Project Creation Template

Select Windows>Console Application
Write appropriate name in ‘Name’ box, change the destination folder of the project directory by clicking the ‘Browse’ button
Click ‘Ok’ button
You will see the following code

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace WalkThrough1

{

class Program

{

static void Main(string[] args)

{

}

Now write the following code snippet into the main method

Console.WriteLine("Hello world");

Console.ReadKey();

Now Press F5 or Click on the Debug button

Figure: Debug Icon

You will see the output given below

Figure: Console Output

Desktop Application

An application (desktop) is a computer program designed to help people perform a certain type of work. In a desktop application users can interact with the application via both keyboard and mouse.

Walkthrough 4: Creating a desktop application

Now we will create a very simple desktop application. In this application, user will click on a button ‘Show’ and a messagebox (a small popup box) will appear displaying ‘Hello World’.

Steps:

1. Start Microsoft Visual Studio 2008

2. Click File>New>Project

3. Select Windows>Windows Forms Application

4. Give an appropriate name and others as the previous walkthrough

5. Click ‘Ok’ button

You will get the following picture in your window

Figure:Default Windows Form

6. Now drag and drop a button from toolbox situated at the left side of your development window.

7. Click on the button

8. Change the Text Property of the button into ‘Show’

This will looks like the following picture.

Figure: Text Property of a TextBox Control

9. Double click on the button of the form and write the following code snippet

private void button1_Click(object sender, EventArgs e)

{

MessageBox.Show("Hello World");

}

10. Now run the application bu clicking on the debug button or pressing F5

11. Click on the ‘Show’ button of the running application

12. A messagebox will appear. You will get the following picture

Figure: Output of the desktop application

Practice:

Create a desktop application like the following figure.

Figure: Information Management Application User Interface

Features:

· After clicking on the save button, all of the information of the textbox will be disappeared.

· Button names are self descriptive. Relevent information will be shown in a messagebox when a button is clicked.

[For advanced users]

Create a calculator which will take two number in two different textboxes. It has four buttons (Add, Subtract, Multiply, Divide). Calculated result will be showed in a label when the button is clicked.

Basics of Programming: Part 1

2009-08-31T16:13:00.007+07:00

We know computer only understands 1s and 0s. Computers do works according the set of these 1s and 0s. These 1s and 0s are called Machine Language.

At the early time of computing, programmers instruct computers by writing directly into Machine Language. But as times go on, works for the computers rises rapidly. And it was very tough for the programmers to write these instructions again and again for separate command. So, they define some set of Machine Code dedicated for some specified works and give them appropriate name. These names are called Keywords. For example: ADD for addition, SUB for subtraction etc. This language is called Assembly Language.

After some times, the keywords weren’t enough for the programmers. So, here comes the thinking of a ‘Set of Keywords’ or Programming Language or High Level Language. Programmers write their program into these languages and these instructions were translated into the machine language for execution. The translator which translates the high level language into machine language is called Compiler. Now a day many compilers are available to write programs.
So, we can say that, computers execute the instructions that are translated into its native language, or Machine Language.

Now, the next question arises, how it deals with data? Suppose a sequence of 1s and 0s are sent to a programmer and also told that “It is data”. Though the programmer knows how to deal with data, but he would reply, “What operations can I do with this data?”. So, we also have to say instruct him he could do some certain operations with this data, and some operations can’t be done.
No matter what are we sending, computer first translates the code into machine language and then stores it. While storing, it also needs some rules and regulations on which it takes the decision of the operations that are valid for that data or not. These rules and regulations are called types. That means, data has types.

So, type defines which operations are valid for that data and which aren’t. We can also call it as Data Type. The main data types one compiler can understand are, Integer, Float, Character, Boolean etc.

So, we now know how the computer deals with data. But how does it store these into its storage?
We can say the storage as Memory. A memory is divided into hundreds and thousands of memory cell. Each of the memory cell has an address and also can store data in it. So, we can say, memory has two parts. Address and Data storage place.

To store something in memory, we can instruct the machine to do so in two ways. We can specify the address of the memory to store the data or we can just ask to store where ever it likes to store. In the second condition, we don’t know the address where the data is going to. To reuse the data in future, instead of retrieveing the memory address of it, we rather give it a name. That means, we give a name to the memory address where the data is going. This name is called Variable Name, and the memory place is called the Variable. So we put our data into the variable and recall the value using the name of the address we have declared before.

Crystal Report for Beginners

2009-07-10T16:25:00.003+07:00

Hello all. I have uploaded a video showing how one can create a crystal report on visual studio 2008 using C# and microsoft access as the database. You can watch the video on the followling link.
Video on how to create a crystal Report for beginners

Object Oriented Programming (Part 1)

2009-03-21T23:26:00.002+06:00

OOP : The Language of GOD

Friends, now a days we see most of the programming languages are object oriented or the procedural lang. are getting converted into object oriented one by one.

Today’s lecture covers on the basics on OOP and the clear view of Class and Objects.

Before begin, let me know what do u think about the OOP with examples.

Well there are numerous answers that we have memorized with examples. But, maximum of us just crammed the definition of the terms of OOP and didn’t think deeply about it.

Now, before jumping in deeply, let me describe you it in brief.

We all know, OOP means Object oriented programming. Which means the orientation between the objects and make the objects works together in our defined way in the virtual world.

Defined way means the programming language. Examples of the programming languages are Fortran, Cobol, C, C++, Java, Python, Cold Fusion, C#, Visual Basic and a lot more.

These languages are of two types. One is Object oriented and the other is structural or procedural programming.

But what’s the difference between these two? Or, what’s the advantage of OOP?

Why OOP?

Procedural programming focus on programs/procedures with the best algorithms. Here, all of the data are shared and all of the code are situated in a single file which is has a very big amount of code.

But object oriented programming focus on the objects of the problem domain and analysis the attributes and functionalities of those objects.

Structural programming has some characteristics.

· It is Top-Down design
· Limited control structure
· Limited scope of data structure
· All are in one file
· Huge line of code

Besides, OOP languages has some advantages:

· Modern thinking
· OOP can be upgrade from small to large scale
· Easy to partition the work
· Reduces the software maintenance & development costs
· Change in user requirement or later development always been a major prob. OOP is the solution.

Object Oriented Thinking:

Now can you tell me what is an object? Ya ya..everything besides us is object. We all know the definition of that.But whats the characteristics of the objects? Or how can we implement the objects in our programming languages?

Let me give you a problem domain.

“ …customers are allowed to have different types of bank accounts, deposit money, withdraw money and transfer money between accounts”

What do you emphasize if you are asked to implement it in program?

Let me guess: you make methods of deposit money, withdraw money and transfer money. Isn’t it?

Wrong…wrong..its totally a wrong way of thinking. Remember, you are in an era of object oriented programming. You have to find the objects from there. Can you find out the objects from this problem domain?

Hmm..you are right..customers, money, account are the objects.

Make the objects in the problem domain mapped in the objects in the software.

Every objects in our world has something and they do something.

The things objects posses or has are data and the things they do are methods in programming language.

From our previous problem domain, we can be clear on this aspect.

Check that, the object ‘Customer’ is a human being. That means he has the attributes of a human being. So, he must have a Name, Age, Address, Social ID etc. These are his data or attributes.

And he can do somekind of works. Some of them are, Walking, Watching , Eating etc. These are the behavior or these thing he can do and we represent these as methods in programming language.

Objects communicate between them with message passing. Data are passed through the method as a message.

Now just look around you and think about 10 objects. And please write down the object names and their data and workings.

Class Vs Objects:

Have you finised writing the object names?? If yes, please again look around you. You can see that there are many objects which are of the same kind. They has the same kind of attributes and they do the work in the same way. More precisely, they are identical in some means. Just their data are changed. We can classify those objects in a single group which has the common attribute names and the functionality they posses.

Suppose, if we think about the pen, we see that, they are of different colors, size, design but they all do the same work, that is writing. Here, the data of the Pen is different but the method is same.

So, we can say that, if we make a blueprint of pen, we make many pen from that blueprint which are of different data with same methods.

A Class is essentially like a blueprint, from which we can create objects. A class defines characteristics of an object, including properties that define the types of the data that the object can contain and methods that describe the behavior of the object. These characteristics determine how other objects can access and work with the data that is contained in the object.

An object is an instance of a class. If a class is like a blueprint, then an object is what is created from that blueprint. The class is the definition of an item; the object is the item. The blueprint for your house is like a class; the house that you live in is an object.

Let me give you some examples to differentiate these two.

Example 1:

Duck class that has certain behaviors, such as walking, quacking, flying, and swimming—and specific properties, such as height, weight, and color.

The Duck class defines what a duck is and what it can do. A Duck object is a specific duck that has a specific weight, color, height, and behavioral characteristics. The duck that you feed is a duck object.

Example 2:

Suppose that a programmer must write a function that changes a customer’s address in a database. In a traditional approach, the programmer may write a ChangeAddress function that takes a database table and row as a parameter and changes the address information in that row. Or, the programmer may use the person’s name as a parameter, search the table for that name, and then change the address in the record. The disadvantage of this approach is that when you want to change the information about the person, you must know something about how that information is represented, in this case, in a specific table in a database.

An object-oriented approach is to define a class that represents customers and provides the ability to change addresses. The application that uses the Customer class is likely to manage multiple customer objects, each representing one customer. Each customer object contains information about the location of that customer’s record in the database, so when the application must change the address information, it can simply invoke the ChangeAddress action or method for that particular customer. The application tells the Customer object to change its address, in effect.

So, we can differentiate between the class with object as:

Class:

· Visible in source code
· The code is not duplicated

Object:

· Own copy of data
· Active in running program
· Occupies memory
· Has the set of operations given in the class

Hope you all understand clearly. If you have further query, feel free to ask me.

My email address: foyzulkarim@gmail.com

Showing Data in DataGridView without using database::

2009-03-21T02:12:00.002+06:00

Sometimes we want to see the values entered in the entry form temporarily and without the querying it from database. This can be done easily by the following procedure.

Suppose, I want to enter student’s name and roll and after clicking the add button, the name and roll of the student will be shown in the datagridview box. Remember, I am not willing to use the database to show the data in the datagridview box.

I am using a desktop application. That’s why I use windows form rather than web page for inputting the values.

I will describe it in several steps for your better understanding.

1. Open your visual studio 2005 and create a new project. Name it meaningfully and place it in a suitable location in your hard drive. Remember, you have to create a windows application.

2. A blank form will appear and you have to design it with your own.

a. Since, we want to add just 2 fields, such as a student’s Name and Roll, you have to take 2 text box fields. For understanding which textbox is what for, you should take 2 label also. Place these labels beside the text boxes and name it meaningfully. I named the components as:

i. TextBoxà nameTextBox, rollTextBox

ii. LabelànameLabel, rollLabel

b. Now add a DataGridView into the form and name it meaningfully. Do nothing in the properties window for this. Just rename it.I named it as:

i. DataGridViewà studentDataGridView

c. Add a button below the textboxes and select a suitable text on the button for display. I name it as:

i. Buttonà addButton

d. If you double click on the button, you will be redirect into the coding page of the form.

3. Now check that, you have to customize the DataGridView field where you want to show the inserted data. To do this, go to your form’s constructor method [public Form1() for me]and create 2data column and add those columns into a table. Table was created as a global variable for accessing it from any method in that class.

a. DataColumnà nameColumn, rollColumn

b. DataTableà myTable

4. Now go into the method of the button click. Into the method, create a new DataRow into the table.

5. Put the two values of the textboxes into the cells of the new row.

6. Add the row values in the table.

7. Now select the table as the data source of the gridview .

I have uploaded the code file both in mediafire and rapidshare. The links are:

Mediafire:

http://www.mediafire.com/?sharekey=9c43b2fe26275d42111096d429abd360e04e75f6e8ebb871

Rapidshare:

http://rapidshare.com/files/211563479/DataGridViewPractice.rar

That’s all I have got here.If you have any query, feel free to ask me. Your comments are very valuable to me.

Download for Free

2009-01-30T21:33:00.005+06:00

Hello all,

sometimes we search ebooks to download for free but couldn't find desired sites.

I am giving here some links where you will find the ebooks totally free of cost.

You will find the ebooks in the following site.

But there are some websites, where you will find not only ebooks but also other document types and ofcourse they are totally free for download.

http://www.esnips.com

Now i am giving some links from where you can download not only ebooks, but also music, bangla drama serials, movies etc. I hope you all will like it. Specially, who speaks in Bengali.

And i will keep continue posting whenever i get new websites that serves files for free.

Still then.

Bye

Helpful Links for Download

2009-01-24T13:27:00.002+06:00

Hello there..
i have uploaded some files on rapidshare. Hope those files will be helpful for you.

Software: Download Accelerator Plus 8 Premium with crack-->http://rapidshare.com/files/188366675/dap_download_accelerator_plus_v8_premium___crack.exe To see how to crack..plz visit http://www.youtube.com/watch?v=IEzI8rxI7dM
Ebooks: http://rapidshare.com/files/186992854/Apress.Android.Essentials.Jul.2008.pdf http://rapidshare.com/files/186997659/McGraw.Hill.Android.A.Programmers.Guide.Jul.2008.eBook-DDU.pdf

Android : The Future of Mobiles

2009-01-19T14:08:00.004+06:00

In this post, i will give a brief on Android. Those who don’t know about it, Android is a mobile operating system built by Google under the first goal of OHA or Open Handset Alliance. It is built in Java but quite different than J2ME. If anyone interested of more information on android, please visit http://code.google.com/android/documentation.html.

Now I will describe you about how you can start working on android.

First of all, remember that Android is not a language or IDE. It’s a kind of operating system. I think I should make it clear to you from my experience.

Think of Microsoft’s Windows XP, Linux, Mac or other operating systems. We, the software developers generally don’t make such type of operating systems but we make applications that will run in those operating systems. We make the applications either Java or C# or others as our choice. These applications executed by the help of the operating systems. They use the resources of the hardware under the management of the os. And, we can see that, the operating systems also have some default applications that the users can use.

Android is such type of operating system that is used in some specific mobile handsets. We make the applications that will run under this os and use the hardware for execution. And, the language used to make such applications is Java.

Now, can we use any java ide for development? The answer is No. Because, Android system has some specific packages that can’t be found all of the ide. Until now, eclipse made android supported ide for application development.

I think it will be helpful for you to understand what is Android and how we can make applications.

Dot Net 2.0 with C# Project

2009-01-19T03:19:00.003+06:00

This is a project built with Microsoft .NET 2.0 with C#. This software calculates the total assets of a whole company.

Links:

http://rapidshare.com/files/185658659/BlackHole.rar.html

http://www.filefactory.com/file/a02827e/n/BlackHole_rar

Object Oriented Programming Principles

2009-01-19T02:53:00.002+06:00

A very good book for building the oop concept

Digital Image Processing

2009-01-19T02:01:00.001+06:00

Here are the links of some power point files that our course teacher used in his lecture on Digital Image Processing course.

http://www.filefactory.com/file/a00ebd6/n/Digital_Image_Processing_1_ppt

http://www.filefactory.com/file/a00ec69/n/Digital_Image_Processing_2_ppt

http://depositfiles.com/files/8edtx6agn

http://depositfiles.com/files/u85zbbovn