Basics of .Net with VB

                                                INTRODUCTION

               The .NET Framework, encompassing a great new product called Visual Studio.NET, is tipped to spur a revolution in the software industry .This is because, the .NET Framework and Visual Studio.NET have been designed with the Internet as their epicenter.

           Visual Basic has been the most widely accepted programming language in the world. Thus, Microsoft was left with no choice but to integrate this product into the .NET Framework in the form of VB.NET.

          Microsoft has introduced a number of contemporary features to VB.NET, and greatly ameliorated its web design facilities.VB.NET is also regarded as the easiest entry-point into the .NET world, that provides succor to those who are terrified of biting the bullet of the Brave New World of technology.

           Microsoft has retained the latest the heart and soul of the original VB product with latest developments available in the software in the software technology. This forms the genesis of VB.NET.

          Visual Basic.NET is primarily an extension of the Visual Basic Programming Language, which is shipped a Visual Basic Product. A is significant upgrade or improvement over VB and is far more flexible and powerful.

                              Minimum Requirements

 

 The software requirements to successfully run the programs are

v  Operating System-Windows 2000,Windows XP, Windows 7

v  Microsoft IIS server 5.0

v  Visual Studio.Net

v  You can choose any database.

                                   Visual Studio.Net

             We can ask for our copy of  this software from Microsoft by placing an order for the same on their website.

                              SQLServer2000

         While installing the evaluation edition of SQLServer2000, we have chosen the default selected settings. The only modification made is in the Authentication Dialog Box.

We see two options

    * Windows Authentication Mode

    * Mixed Mode (Windows Authentication and SQL Server Mode)

 The default option selected is Windows Authentication mode. We have instead selected Mixed mode. Once this option is selected, the password text boxes for the ‘sa’ user get activated. As we could prefer using a blank password in our programs, we select Blank Password .on selecting this option, the text boxes get disabled again.

   

n  .NET FRAMEWORK AND VB.NET

Ø  It is not a programming language, but it supports programming languages.

Ø  The .net framework is a new easy and extensive programming platform.

Ø  By default the .Net framework comes with few programming languages including VB.NET, C#(C SHARP), J# and managed C++.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Ø  The .Net framework serves as common platform for all these languages.

Ø  It gives a common class library which can be utilized by any of these languages.

Ø  So programmers need not learn any new library when they switch from one .Net language to another language .Only the syntax is different for each .NET language.

Ø  The .NET is a major technology change. Just like the computer world moved from DOS to Windows, Microsoft is now moving to .NET.

Evolution of the .NET Framework

v  Visual basic, which has the Microsoft’s most popular language earlier, was too easy, and many serious programmers hated it just for that reason.

v  Even though visual Basic was very easy to use, it was not flexible enough to develop complex application.

v  Microsoft’s VC++ was a powerful tool.

v  It had too many data types, and programmers had to learn many libraries including Windows SDK,MFC,ATL,COM etc.

v  There were many data type compatibility issues while exchanging data between different layers.

v  The java language became a very good choice for this reason.

v  It had the flexibility and power of C++ and at the same time easy enough to catch the tension of VB programmers.

v  Microsoft recognized these factors and they introduced the .NET.

v  All unwanted complexities were eliminated and a pure object oriented programming model was introduced.

v  .NET framework comes with a single class library.

v  Whether we write code in VB.NET or C# or J#, we just use the .net class library.

v  There is no class’s specific to any .NET language.

v  There is nothing more we can do in a .NET language.

v  We can write code in VB.NET or C# with the same number of lines of code, same performance and same efficiency, because everyone use same .NET class Library.

v  When we write code in any .NET language and compile, it will be converted to an Intermediate language (Microsoft Intermediate Language-MSIL).

v  So, our compiled code contains the MSIL code and not the executable machine language code.

v  When the .net applications runs, the .NET framework is the target computer takes care of the execution.

v  To run a .NET application, the target computer should have .NET framework installed in it.

v  The .NET framework converts the calls to .NET class libraries to the corresponding ApIs of the Operating System.

v  Whether we write code in VB.NET or C#, we are invoking the methods in the same .NET class libraries.

v  The same .NET framework executes the VB.NET and C# application .

v  So there won’t be any performance difference based on the language we write code.

v  The VB.NET code we write is platform independent, because whatever we write getting compiled into MSIL.

v  There is no native code, which depends on our operating system or CPU.

v  But when we execute the MSIL, the .NET framework in the target system will convert the MSIL into native platform code.

v  So, if we run out .NET exe in a Window machine, the .net framework for Windows will convert it into Windows native code and execute.

v  If we run our .NET application in Linux machine, the .NET framework for Linux will convert our code into Linux native code and execute.

v  So our code is purely platform independent and runs anywhere.

VB.NET

q  The next version of SQL Server even supports writing stored procedure in .NET languages.

q  .NET runtime will be part of all Operating Systems by default.

q  In short if we like to work on Microsoft technologies for programming .net will be only choice we will have.

n  GETTING STARTED TO VB.NET

 TO SELECT A NEW PROJECT OR TO OPEN AN EXISTING PROJECT

n  TO SELECT A NEW PROJECT 

n  SAVING THE NEW PROJECT BY GIVING A NAME

n  THE NEW PROJECT FORM

n  TO RUN THE      FORM(PROJECT) OR TO VIEW OUTPUT

 n  AFTER THE PROJECT IS BEEN RUN

 n  SELECTING THE TOOLBOX

n  SELECTING AND PLACING A TOOL FROM THE TOOL BOX 

           by just drag and drop.

n  EXECUTION OF THE FORM ALONG WITH THE TOOLS FROM THE TOOL BOX

 METHODS:

                  A method is a self-contained entity that carries out a well-defined task of some kind.

Types of Methods:

Two types of  methods in vb.net.Subroutines, which do not return  values.

Functions, which do return  values.

        1.”Value”type parameters:

     

• Declared with an explicit  ByVal  modifier. ByRef modifier can’t be specified.                                     
• To exist upon  the completion of the execution of the method.
• To assign a new value to a value parameter.

        2.”Reference” type parameters

• Declared with a ByRef modifier.
• ByVal modifier can’t be used.
• Does not create a new storage location.
• Modification of a reference parameter directly and immediately impacts the  corresponding argument.

3.”ParamArray”type parameters

o   Declared with the ParamArray modifier.

o   Its type must be a one-dimensional array.

o   And it must be the last parameter in the formal parameter list.

o   Not possible to combine the ParamArray modifier with the ByRef modifier.

4.Method Overloading

o   Refers to the use of the same entity for different purposes.

o   Use the same method name to create two or more methods that perform similar tasks.

 ARRAYS:

Arrays can be thought of as containers that have a list of storage locations for a specified data type.

Type of Arrays:

• One-dimensional Arrays:

When declaring a one-dimensional array we specify the type, array name, dimensions and size.

Dim MyArray(10) as Integer

Dim MySingleArray() as Integer

Dim MySingleArray() as Integer={1,2,6,8}

• Two-dimensional Arrays:

Vb.net , an array can be have as many as 32 dimensions

• Jagged Arrays:

We specify the type, array name, dimensions and size.

The memory for each row in a jagged array is to be allocated separately.

Additional Windows Controls-1

Used  for Developing Windows Applications.

1.Docking Controls.

2.Timer Control.

3.ProgressBar Control

4.Mouse Events

5.Key press Events

6.Linklabel Control.

7.TrackBar Control

8.Panel Control

9.Tree view Control.

1.Docking Controls

• To specify the way in which the control will be docked to the parent control.
• Various values of Dock property are:
• Top, Left, fill, right, bottom  and none. Default value of this property is none.

2.Timer Control

• While most of the controls that we place on the form are visible during run-time,some of them are not visible during run-time.

For example:

• Mainmenu, timer, tooltip  and  notifyicon controls are not visible during run-time. such controls are placed in the component tray.
• Timer control is used to do some work repeatedly at predefined time intervals.
• The default time interval is 100 milliseconds.

3. ProgressBar Control

• We use the progress-bar control in a project to indicate the progress of some work, like copying a voluminous data file.

The Properties :

• Minimum, Maximum  and Value.
• Default value of Minimum and Maximum properties are 0 and 100.
• The value of the predefined value property should lie in this rang.

 4. Mouse Events

• Important mouse events: MouseMove, MouseUp  and MouseDown.

5. Key Press Events

• Just like the mouse events,the key event shall be used to get an action performed.

6. Linklabel Control

• It is a general-purpose control.
• In windows applications to establish a link from one form to another.
• It shall also be used to start familiar system programs,such as notepad,PaintBrush and InternetExplorer.

7. TrackBar Control

• The trackbar is more or less like the traditional scrollbar.it allows the user to select a value from a range of values.
• When we create a trackbar object ,we have to specify the minimum and maximum bounds of the range.
• We can set all these values through the appropriate properties of the trackbar control.

8. Panel Control

• It contains other controls.
• We shall group a set of related controls and place them inside a Panel control.
• Two properties : AutoScroll , BorderStyle.

9.TreeView Control

• It displays data in a hierarchical format.
• It displays the text that describes the objects in the list.
• The treeView control maintains a collection of treeNode objects.
• We can map each treenode  object with a file or folder that it represents.

 Additional Windows Control-2

1. Menu Control

           MenuItem class

      2.Context Menu

     

     3. SDI(Single Document Interface)

     4. MDI(Multiple Document Interface)

     5.Dialog Boxes

   

     6.ToolBar Control

    

     7.Tab Control

     8.Dealing with Controls at runtime.

Context Menu

 Context menus pop up on the screen  when we right-click a control.

SDI(Single Document Interface)

• Only a single  document can be opened at a time in such as interface.Notepad is a good example of SDI.
• If we wish to open a new document ,we have to open a new instance of SDI.

Dialog Boxes

• It is used to receive some simple input from the user.

ToolBar Control

• The tool bar buttons are as used as alternative means of activating the menu items.
• A tool bar may contain two or more tool bar buttons. Each such button may contain  text, image or both.

 StatusBar Control

• The Status bar appears at the bottom of the form.
• It can be divided into two or more panes.
• Each pane shall contain either textual or graphical or both of these types of information.

                                  CLASS AND OBJECTS

•       A  Class is defined as a collection of variables and methods that act upon those variables.

•       The variables are also known as fields. The fields and methods in a class are known as class members.

•       A class can be thought of as a container, which holds several class members.

•       Classes serve as building blocks in OOprograms. A class shall represent a room, a person, an inventory item, a Savings-Bank account or any entity that an OOprograms handles.

                                          INHERITANCE

Introduction

            Inheritance is one of the primary concepts of object-oriented programming. It allows us to reuse existing code.

       Through effective employment of inheritance,

         we can save considerable amount of time in our programming.

   All pre-defined classes in VB.NET are derived from a simple pre-defined class known as object.    

   The polymorphism feature enables us to define a method in a base class and a method in a derived class in such a way that both of them have the same signature but they have different functionalities

                                  Virtual Methods

•       We shall refer to a derived class object through a base class reference.

•       A reference to a base class has two types. what it was declared as is called static type. what it is currently referring to is called dynamic type.

•       Sometimes we may wish the compiler to use a reference’s dynamic type resolve the call as run-time.

•       We shall use the concepts of virtual methods in such situations.

•       A virtual method is one method where the decision on exactly which method invoke is delayed until run-time, allowing dynamic type of reference to be used.

Defining and usages of interfaces

•       The main purpose of an interface is to declare a set of methods, and not to implement them.

•       Therefore, an interface only includes method declaration and not their implementations.

                                    Namespaces

•       A namespace shall be viewed as a container for classes and interfaces.

•       There are over 60 predefined namespaces in the .NET framework.

•       A namespace is like a directory. by placing the classes and interfaces into namespaces, we can easily group related classes and interfaces together.

•       We can also avoid the risk of name collisions.

•       If one company happens to define a class that has the same name as the class written by another company, and there are no namespaces

•       There will be no way for a compiler to figure out which class a program is actually referring to.

•       With the introduction of namespace, there is in this regard no problem because the two classes will be placed in two different namespaces.as we know,it is like the windows file system,where files with same can be contained in different folders.

•       Just as folders on this file system can contain other folders as well as files, namespaces shall contain other namespaces and classes.

                     Exception Handling

•       An exception handling is an abnormal condition

That is caused by an run-time error in the program.

VB.NET enables us to smoothly handle the various types of exceptions that occur during the execution of a program with the well defined exception handling mechanism.

   ArgumentException

   ArithmeticException

   ArrayTypeMismatchException

   CoreException

   dividebyzeroexception

   FormatException

   IndexOutOfRangeException

   SqlException

   IOException

   InvalidCastException

   NullReferenceException

   OutOfMemoryException

   outOfMemoryException

Thank you,
Rudhra Devan
Shanmugam Kalyani Systems.
Thanjavur.TN.India.
please give your feedback to rudhradevan@gmail.com