Unit I
Evolution of .Net Framework
First Introduced in early 2000’s and has gone through several versions and updates.
Year
2002
2003
2005
2006
2007
2010
.NET
CLR
Visual
Version Version Studio
1.0
1.1
2.0
3.0
3.5
4.0
1.0
Visual
Studio
.NET
2002
1.1
Visual
Studio
.NET
2003
2.0
2.0
Visual
Studio
2005
Visual
Studio
2005
2.0
Visual
Studio
2008
4.0
Visual
Studio
2010
Features and Enhancements
Aimed to simplify application development and
improves security
It included a runtime environment called the Common
Language Runtime and a class Library that provide a
wide range of pre built functionality.
Added support for ADO.NET classes for Oracle database
and ODBC database connectivity.
Introduce Significant improvements, including the Generic
feature, which allowed developers to create more efficient
and type safe code.
Brought enhancement to Web development, ASP.net and
ADO.net
Although It didn’t introduce a new version of the CLR, this
release added new libraries and APIs for Windows
Presentation
Foundation,
(WPF),
Windows
Communication Foundation (WCF), Windows Workflow
Foundation (WWF) and more.
These technologies aimed to simplify building windows
desktop applications, communication between services,
and workflow based applications
This version built upon previous release by adding features
like Language Integrated Query (LINQ) and
improvements to ASP.net, WCF and WPF.
This release introduced major enhancements, including
Task Parallel Library (TPL) for improved parallel
programming, dynamic language runtime (DLR) Managed
1
2012
4.5
4.0
2013
4.5.1
4.0
2014
4.5.2
4.0
2015
4.6
4.0
2017
4.7
4.0
2019
4.8
4.0
2022
6
6.0
Visual
Studio
2012
Visual
Studio
2013
Visual
Studio
2013
Visual
Studio
2015
Visual
Studio
2017
Visual
Studio
2019
Visual
Studio
2022
Extensibility Framework (MEF)nwere introduced in this
release.
Improvements to asynchronous programming with the
introduction of the async and await keywords.
Support for Windows Store, enhancements of WPF, WCF,
WWF, MEF, and ASP.NET.
Performance and debugging improvements.
ASP.NET, APIs enhancements, New Workflow features
and Debugging improvements features were added in this
release.
It focused on improving performance, security and adding
various enhancements to existing features.
New 64-bit JIT compiler, Assembly Loader
improvements, enhancements to Garbage Collector.
High DPI support for Windows Forms controls, Touch
support for WPF in Windows 10, Enhanced cryptography
support, performance, and reliability improvements.
JIT improvements, Malware scanning for Assemblies and
Accessibility Enhancements
AI assisted development, Azure Cloud App Support,
Integration with Git and GitHub
Overview of the .Net Framework
The .NET Framework is a software development framework developed by
Microsoft that provides a runtime environment and a set of libraries and tools for
building and running applications on Windows operating systems.
The framework includes a variety of programming languages, such as C#, F#, and
Visual Basic, and supports a range of application types, including desktop, web,
mobile, and gaming applications.
.NET Framework is designed to fulfill the following objectives:
• Provide a consistent, object-oriented programming environment whether
object code is stored and executed locally, or executed remotely.
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• Provide a code-execution environment that:
✓ Minimizes software deployment and versioning conflicts.
✓ Promotes safe execution of code, including code created by an unknown
or semi-trusted third party.
✓ Eliminates the performance problems of scripted or interpreted
environments.
• Make the developer experience consistent across widely varying types of
apps, such as Windows-based apps and Web-based apps.
• Build all communication on industry standards to ensure that code based on
.NET Framework integrates with any other code.
Advantage of .Net framework
1. It support for a variety of programming languages.
2. It support variety of application types. The framework includes libraries and tools
for creating desktop, web, mobile, and gaming applications, which makes it a
versatile choice for developers working on a wide range of projects.
3. The .NET Framework improves the security, reliability, and performance of
applications. These include features such as code access security, automatic memory
management, and just-in-time (JIT) compilation, which helps improve the speed of
application execution.
4. The .NET Framework is also designed to integrate with other Microsoft
technologies, such as Microsoft SQL Server, Microsoft SharePoint, and Microsoft
Office, which can make it easier to build applications.
5. .NET Framework is a powerful and versatile development platform that provides a
wide range of tools and libraries for building and running applications on Windows
operating systems.
6. It is a virtual machine for compiling and executing programs written in different
languages like C#, VB.Net, etc.
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7. It is used to develop Form-based applications, Web-based applications, and Web
services.
8. .NET Framework supports more than 60 programming languages of which 11
programming languages are designed and developed by Microsoft. The remaining
Non-Microsoft Languages are supported by .NET Framework but not designed and
developed by Microsoft.
Disadvantages of .NET Framework:
1. Windows dependency: Although the .NET Framework can run on multiple operating
systems, it was originally designed for use on Windows operating systems, which
means that it may not be the best choice for cross-platform applications.
2. Large footprint: The .NET Framework has a large installation footprint, which can
make it difficult to deploy applications on systems with limited storage or
bandwidth.
3. Licensing: Some versions of the .NET Framework require a license, which can add
to the cost of developing and deploying applications.
4. Performance: While the .NET Framework provides good performance for most
applications, it may not be the best choice for high-performance applications that
require low-level access to hardware or complex algorithms.
5. Learning curve: Although the .NET Framework is designed to be easy to use, it still
has a learning curve, especially for developers who are new to the platform or to
object-oriented programming in general.
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Components of .NET Framework
There
following components of .NET Framework:
1.
2.
3.
4.
5.
I.
are
CLR (Common Language Runtime)
CTS (Common Type System)
BCL (Base Class Library)
CLS (Common Language Specification)
FCL (Framework Class Library)
CLR (common language runtime)
.NET CLR is a runtime environment that manages and executes the code written in
any .NET programming language. CLR is the virtual machine component of the
.NET framework. That language's compiler compiles the source code of applications
developed using .NET compliant languages into CLR's intermediate language called
MSIL, i.e., Microsoft intermediate language code. This code is platformindependent.
The main Component of CLR are
o
o
o
Class Loader - Used to load all classes at run time.
MSIL to Native code - The Just In Time (JIT) compiler will convert MSIL
code into native code.
Code Manager - It manages the code at run time.
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o
o
o
Garbage Collector - It manages the memory. Collect all unused objects and
deallocate them to reduce memory.
Thread Support - It supports the multithreading of our application.
Exception Handler - It handles exceptions at run time.
.NET CLR Functions
Following are the functions of the CLR.
II.
o
It converts the program into native code.
o
Handles Exceptions
o
Provides type-safety
o
Memory management
o
Provides security
o
Improved performance
o
Language independent
o
Platform independent
o
Garbage collection
o
Provides language features such as inheritance, interfaces, and overloading
for object-oriented programs.
CTS (Common Type System)
CTS purovides guidelines for declaring, using, and managing data types at runtime.
It offers cross-language communication. For example, VB.NET has an integer data
type, and C# has an int data type for managing integers. After compilation, Int32 is
used by both data types. So, CTS provides the data types using managed code. A
common type system helps in writing language-independent code.
It provides two categories of Types.
1. Value Type: A value type stores the data in memory allocated on the stack or
inline in a structure. This category of Type holds the data directory. If one
variable's value is copied to another, both the variables store data
independently. It can be of inbuilt-in types, user-defined, or enumerations
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types. Built-in types are primitive data types like numeric, Boolean, char, and
date. Users in the source code create user-defined types. An enumeration
refers to a set of enumerated values represented by labels but stored as a
numeric type.
2. Reference Type: A Reference type stores a reference to the value of a
memory address and is allocated on the heap. Heap memory is used for
dynamic memory allocation. Reference Type does not hold actual data
directly but holds the address of data. Whenever a reference type object is
made, it copies the address and not actual data. Therefore two variables will
refer to the same data. If data of one Reference Type object is changed, the
same is reflected for the other object. Reference types can be self-describing
types, pointer types, or interference types. The self-describing types may be
string, array, and class types that store metadata about themselves.
III.
BCL (Base Class Library)
The base class library has a rich collection of libraries features and functions that
help to implement many programming languages in the .NET Framework, such as
C #, F #, Visual C ++, and more. Furthermore, BCL divides into two parts:
❖ User defined class library
✓ Assemblies - It is the collection of small parts of deployment an
application's part. It contains either the DLL (Dynamic Link Library) or
exe (Executable) file.
❖ Predefined class library
✓ Namespace - It is the collection of predefined class and method that
present in .Net. In other languages such as, C we used header files, in java
we used package similarly we used "using system" in .NET, where using
is a keyword and system is a namespace.
IV.
CLS (Common language Specification)
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It is a subset of common type system (CTS) that defines a set of rules and regulations
which should be followed by every language that comes under the .net framework.
In other words, a CLS language should be cross-language integration or
interoperability. For example, in C# and VB.NET language, the C# language
terminate each statement with semicolon, whereas in VB.NET it is not end with
semicolon, and when these statements execute in .NET Framework, it provides a
common platform to interact and share information with each other.
V.
FCL (Framework Class Library)
It provides the various system functionality in the .NET Framework, that includes
classes, interfaces and data types, etc. to create multiple functions and different types
of application such as desktop, web, mobile application, etc. In other words, it can
be defined as, it provides a base on which various applications, controls and
components are built in .NET Framework.
Key Components of FCL
✓
✓
✓
✓
✓
✓
Object type
Implementation of data structure
Base data types
Garbage collection
Security and database connectivity
Creating common platform for window and web-based application
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Basic Definition
WinForms
Windows Forms is a smart client technology for the .NET Framework, a set of
managed libraries that simplify common application tasks such as reading and
writing to the file system.
ASP.NET
ASP.NET is a web framework designed and developed by Microsoft. It is used to
develop websites, web applications, and web services. It provides a fantastic
integration of HTML, CSS, and JavaScript. It was first released in January 2002.
ADO.NET (ActiveX Data Objects)
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ADO.NET is a module of .Net Framework, which is used to establish a connection
between application and data sources. Data sources can be such as SQL Server and
XML. ADO .NET consists of classes that can be used to connect, retrieve, insert,
and delete data.
WPF (Windows Presentation Foundation)
Windows Presentation Foundation (WPF) is a graphical subsystem by Microsoft for
rendering user interfaces in Windows-based applications. WPF, previously known
as "Avalon", was initially released as part of .NET Framework 3.0 in 2006.
WPF uses DirectX.
WCF (Windows Communication Foundation)
It is a framework for building service-oriented applications. Using WCF, you can
send data as asynchronous messages from one service endpoint to another.
WF (Workflow Foundation)
Windows Workflow Foundation (WF) is a Microsoft technology that provides an
API, an in-process workflow engine, and a rehostable designer to implement longrunning processes as workflows within .NET applications.
LINQ (Language Integrated Query)
It is a query language, introduced in .NET 3.5 framework. It is used to make the
query for data sources with C# or Visual Basics programming languages.
Entity Framework
It is an ORM based open source framework which is used to work with a database
using .NET objects. It eliminates a lot of developers' effort to handle the database. It
is Microsoft's recommended technology to deal with the database.
Parallel LINQ
Parallel LINQ or PLINQ is a parallel implementation of LINQ to objects. It
combines the simplicity and readability of LINQ and provides the power of parallel
programming. It can improve and provide fast speed to execute the LINQ query by
using all available computer capabilities.
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AJAX
AJAX is a web development technique for creating interactive web applications. If
you know JavaScript, HTML, CSS, and XML, then you need to spend just one hour
to start with AJAX.
Why to Learn Ajax?
AJAX stands for Asynchronous JavaScript and XML. AJAX is a new technique for
creating better, faster, and more interactive web applications with the help of XML,
HTML, CSS, and Java Script. With the help of AJAX we can communicate with
server without page reload.
● Ajax uses XHTML for content, CSS for presentation, along with Document Object
Model and JavaScript for dynamic content display.
● Conventional web applications transmit information to and from the sever using
Synchronous requests. It means you fill out a form, hit submit, and get directed to a
new page with new information from the server.
● With AJAX, when you hit submit, JavaScript will make a request to the server,
interpret the results, and update the current screen. In the purest sense, the user would
never know that anything was even transmitted to the server.
● XML is commonly used as the format for receiving server data, although any
format, including plain text, can be used.
● AJAX is a web browser technology independent of web server software.
● A user can continue to use the application while the client program requests
information from the server in the background.
Rich Internet Application Technology
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AJAX is the most viable Rich Internet Application (RIA) technology so far. It is
getting tremendous industry momentum and several tool kit and frameworks are
emerging. But at the same time, AJAX has browser incompatibility and it is
supported by JavaScript, which is hard to maintain and debug.
AJAX is Based on Open Standards
AJAX is based on the following open standards −
● Browser-based presentation using HTML and Cascading Style Sheets (CSS).
● Data is stored in XML format and fetched from the server.
● Behind-the-scenes data fetches using XMLHttpRequest objects in the browser.
● Java Script to make everything happen.
Where it is used?
There are too many web applications running on the web that are using ajax
technology like gmail, facebook, twitter, google map, youtube etc.
How AJAX Works
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Example Program
<!DOCTYPE html>
<html>
<body>
<div id="demo">
<h2>Let AJAX change this text</h2>
<button type="button" onclick="loadDoc()">Change Content</button>
</div>
</body>
</html>
function loadDoc() {
const xhttp = new XMLHttpRequest();
xhttp.onload = function() {
document.getElementById("demo").innerHTML = this.responseText;
}
xhttp.open("GET", "ajax_info.txt", true);
xhttp.send();
}
Windows Forms
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Windows Forms is a UI framework for building Windows desktop apps. It provides
one of the most productive ways to create desktop apps based on the visual designer
provided in Visual Studio. Functionality such as drag-and-drop placement of visual
controls makes it easy to build desktop apps.
Let's start with creating a Window Forms Application by following the following
steps in Microsoft Visual Studio - File → New Project → Windows Forms
Applications
Finally, select OK, Microsoft Visual Studio creates your project and displays
following window Form with a name Form1.
Visual Basic Form is the container for all the controls that make up the user interface.
Every window you see in a running visual basic application is a form, thus the terms
form and window describe the same entity. Visual Studio creates a default form for
you when you create a Windows Forms Application.
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Every form will have title bar on which the form's caption is displayed and there will
be buttons to close, maximize and minimize the form shown below –
If you click the icon on the top left corner, it opens the control menu, which contains
the various commands to control the form like to move control from one place to
another place, to maximize or minimize the form or to close the form.
Form Properties
Following table lists down various important properties related to a form. These
properties can be set or read during application execution.
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Properties
Description
BackColor
Sets the form background color.
BorderStyle
The Border Style property determines the style of the form's
border and the appearance of the form –
● None − Borderless window that can't be resized.
● Sizable − This is default value and will be used for
resizable window that's used for displaying regular forms.
● Fixed3D − Window with a visible border, "raised"
relative to the main area. In this case, windows can't be
resized.
● FixedDialog − A fixed window, used to create dialog
boxes.
● FixedSingle − A fixed window with a single line
border.
● FixedToolWindow − A fixed window with a Close
button only. It looks like the toolbar displayed by the
drawing and imaging applications.
● SizableToolWindow − Same as the FixedToolWindow
but resizable. In addition, its caption font is smaller than
the usual.
ControlBox
By default, this property is True and you can set it to False to
hide the icon and disable the Control menu.
Enabled
If True, allows the form to respond to mouse and keyboard
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events; if False, disables form.
Font
This property specify font type, style, size
Form Methods
The following are some of the commonly used methods of the Form class. You can
refer to Microsoft documentation for a complete list of methods associated with
forms control −
Method Name
Description
Activate - Activates the form and gives it focus.
ActivateMdiChild - Activates the MDI child of a form.
Close - Closes the form.
Focus - Sets input focus to the control.
Hide - Conceals the control from the user.
Refresh - Forces the control to invalidate its client area and immediately redraw
itself and any child controls.
Show - Displays the control to the user.
Form Events
Following table lists down various important events related to a form. You can refer
to Microsoft documentation for a complete list of events associated with forms
control −
Event
Description
Activated
Occurs when the form is activated in code or by the user.
Click
Occurs when the form is clicked.
Closed
Occurs before the form is closed.
Closing
Occurs when the form is closing.
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DoubleClick
Occurs when the form control is double-clicked.
DragDrop
Occurs when a drag-and-drop operation is completed.
GotFocus
Occurs when the form control receives focus.
KeyDown
Occurs when a key is pressed while the form has focus.
KeyPress
Occurs when a key is pressed while the form has focus.
KeyUp
Occurs when a key is released while the form has focus.
Load
Occurs before a form is displayed for the first time.
LostFocus
Occurs when the form loses focus.
MouseDown
Occurs when the mouse pointer is over the form and a mouse
button is pressed.
MouseEnter
Occurs when the mouse pointer enters the form.
MouseHover
Occurs when the mouse pointer rests on the form.
MouseLeave
Occurs when the mouse pointer leaves the form.
MouseMove
Occurs when the mouse pointer is moved over the form.
MouseUp
Occurs when the mouse pointer is over the form and a mouse
button is released.
The ASP Technology
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ASP and ASP.NET are server side technologies.
Both technologies enable computer code to be executed by an Internet server.
When a browser requests an ASP or ASP.NET file, the ASP engine reads the file,
executes any code in the file, and returns the result to the browser.
ASP.NET
ASP.NET is a web application framework developed and marketed by Microsoft to
allow programmers to build dynamic web sites. It allows you to use a full featured
programming language such as C# or VB.NET to build web applications easily.
ASP.NET was released in 2002 as a successor to Classic ASP.
ASP.NET pages have the extension .aspx and are normally written in C# (C sharp).
ASP.NET 4.6 is the latest official version of ASP.NET.
ASP.NET 5 was expected to be an important redesign of ASP.NET.
However, the development of ASP.NET 5 was stopped in favor of ASP.NET Core.
ASP.NET is a web development platform, which provides a programming model, a
comprehensive software infrastructure and various services required to build up
robust web applications for PC, as well as mobile devices.
ASP.NET works on top of the HTTP protocol, and uses the HTTP commands and
policies to set a browser-to-server bilateral communication and cooperation.
ASP.NET is a part of Microsoft .Net platform. ASP.NET applications are compiled
codes, written using the extensible and reusable components or objects present in
.Net framework.
These codes can use the entire hierarchy of classes in .Net framework.
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The ASP.NET application codes can be written in any of the following languages:
● C#
● Visual Basic.Net
● Jscript
● J#
ASP.NET is used to produce interactive, data-driven web applications over the
internet. It consists of a large number of controls such as text boxes, buttons, and
labels for assembling, configuring, and manipulating code to create HTML pages.
ASP.NET Web Forms Model
ASP.NET web forms extend the event-driven model of interaction to the web
applications. The browser submits a web form to the web server and the server
returns a full markup page or HTML page in response.
All client side user activities are forwarded to the server for stateful processing. The
server processes the output of the client actions and triggers the reactions.
Now, HTTP is a stateless protocol. ASP.NET framework helps in storing the
information regarding the state of the application, which consists of:
● Page state
● Session state
The page state is the state of the client, i.e., the content of various input fields
in the web form.
The session state is the collective information obtained from various pages the
user visited and worked with, i.e., the overall session state.
The ASP.NET Component Model
The ASP.NET component model provides various building blocks of ASP.NET
pages. Basically it is an object model, which describes:
● Server side counterparts of almost all HTML elements or tags, such as <form>
and <input>.
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● Server controls, which help in developing complex user-interface. For example,
the Calendar control or the Gridview control.
ADO.NET
ADO.NET provides a bridge between the front end controls and the back end
database. The ADO.NET objects encapsulate all the data access operations and the
controls interact with these objects to display data, thus hiding the details of
movement of data.
The following figure shows the ADO.NET objects at a glance:
The DataSet Class
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The dataset represents a subset of the database. It does not have a continuous
connection to the database. To update the database a reconnection is required. The
DataSet contains DataTable objects and DataRelation objects. The DataRelation
objects represent the relationship between two tables.
Following table shows some important properties of the DataSet class:
Properties
CaseSensitive
Description
Indicates whether string comparisons within the data tables are casesensitive.
DataSetName Gets or sets the name of the current data set.
Tables
Returns the collection of DataTable objects.
The following table shows some important methods of the DataSet class:
Methods
Copy
BeginInit
Clear
Description
Copies both structure and data.
Begins the initialization of the DataSet. The initialization occurs
at run time.
Clears data.
EndInit
Ends the initialization of the data set.
Equals(Object)
Determines whether the specified Object is equal to the current Object.
Finalize
Free resources and perform other cleanups.
Merge()
Merges the data with data from another DataSet. This method has
different overloaded forms.
The DataTable Class
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The DataTable class represents the tables in the database. It has the following
important properties; most of these properties are read only properties except the
Primary Key property:
Properties
Columns
Description
Returns the Columns collection.
Constraints
Returns the Constraints collection.
DataSet
Returns the parent DataSet.
PrimaryKey
Gets or sets an array of columns as the primary key for the
table.
Rows
Returns the Rows collection.
The following table shows some important methods of the DataTable class:
Methods
Description
AcceptChanges
Commits all changes since the last AcceptChanges.
Clear
Clears all data from the table.
GetErrors
Returns an array of rows with errors.
LoadDataRow
Finds and updates a specific row, or creates a new one, if
not found any.
Reset
Resets the table to its original state.
Merge
Merges the table with another DataTable.
NewRow
Creates a new DataRow.
The DataRow Class
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The DataRow object represents a row in a table. It has the following important
properties:
Properties
Description
HasErrors
Indicates if there are any errors.
Items
Gets or sets the data stored in a specific column.
ItemArrays
Gets or sets all the values for the row.
Table
Returns the parent table.
The following table shows some important methods of the DataRow class:
Methods
Description
BeginEdit
Begins edit operation.
CancelEdit
Cancels edit operation.
Delete
Deletes the DataRow.
EndEdit
Ends the edit operation.
The DataAdapter Object
The DataAdapter object acts as a mediator between the DataSet object and the
database. This helps the Dataset to contain data from multiple databases or other
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data source.
The DataReader Object
The DataReader object is an alternative to the DataSet and DataAdapter
combination. This object provides a connection oriented access to the data
records in the database. These objects are suitable for read-only access, such as
populating a list and then breaking the connection.
DbCommand and DbConnection Objects
The DbConnection object represents a connection to the data source. The
connection could be shared among different command objects.
The DbCommand object represents the command or a stored procedure sent to
the database from retrieving or manipulating data.
Then you execute the program, observe the following:
● The application first creates a data set and binds it with the grid view
control using the DataBind() method of the GridView control.
● The Createdataset() method is a user defined function, which creates a
new DataSet object and then calls another user defined method
CreateStudentTable() to create the table and add it to the Tables
collection of the data set.
● The CreateStudentTable() method calls the user defined methods
AddNewColumn() and AddNewRow() to create the columns and rows
of the table as well as to add data to the rows.
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When the page is executed, it returns the rows of the table as shown:
Features of .NET Framework / Benefits of .NET Framework
● OOPs Support: .NET provides a fully object oriented environment. The
philosophy of .NET is – “Object is mother of all.” Languages like Visual Basic.NET
now support many of the OO features that were lacking traditionally. Even primitive
types like integers and characters can be treated as objects – something not available
even in OO languages like C++.
● Support for Multiple Languages and Language Interoperability: The CLR
executes binary code called MSIL (Microsoft intermediate language), and that code
looks the same regardless of the original source language. Within the .NET
Framework is a compiler called the Just-In-Time, or JIT, compiler. It compiles the
MSIL down to machine specific code. All .NET –enabled languages use the same
data types and the same interfacing conventions. This makes it possible for all .NET
languages to interoperate transparently.
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● Cross-platform support: Any windows operating system that supports the
Common Language Runtime (CLR) can execute a .NET application, i.e. .NET
application enables interoperability between multiple windows system.
● Rich Functionality out of the box: .NET framework contains hundreds of classes
that provide a variety of functionality ready to use in the application to perform many
operations such as file IO, network communication and so on.
● Easy Deployment: Executable modules in .NET are self-describing. Once the
Common Language Runtime (CLR) knows where a module resides, it can find out
everything else it needs to know to run the module, such as the module’s object
interface and security requirements, from the module itself. That means a module
can just be copied to a new environment and immediately executed.
● Code Access Security: .NET supplies a standard security mechanism, available
to all parts of the application and also gives automatic access to benefits such as
garbage collection (which destroys objects and reclaims memory for you) and more.
● Debugging Tools: .NET provides integrated debugging tools. Any language that
targets the .NET Framework can be debugged with that single debugger.
● Distributed Systems: Microsoft.NET supports developing globally distributed
systems using which from servers to Wireless Palmtops, with everything in between,
will share the same general platform, with versions of .NET available for all of them,
and with each of them able to integrate transparently with the others.
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● Richer User Interface: There are commonly used controls, such as Labels and
Text Boxes, in both, with similar sets of properties and method and hence
development of the internet environment looks very much like development for
other types of software. The built-in intelligence of Web Forms allows rich, browserindependent screens to be developed quickly, and to be easily integrated with
compiled code. Microsoft has announced an initiative for the future called the
Universal Canvas which builds upon the XML standards to transform the internet
from a Read only environment into a read/write platform, enabling users to
interactively create, browse, edit and analyze information. The universal canvas can
bring together multiple sources of information anywhere in the world to enable
seamless data access and use.
● Extendibility: The completely object based approach of .NET is designed to allow
base functionality to be extended through inheritance (unlike COM) and the
platform’s functionality is appropriately partitioned to allow various parts (such as
the just-in-time compilers) to be replaced as new versions are needed. It is likely
that, in the future, new ways of interfacing to the outside world will be added to the
current trio of windows Form, Web Forms, and Web Services such as universal
Canvas.
● Portability of compiled Applications: .NET allows the future possibility of
moving software to other hardware and operating system platforms. The ultimate
goal is that compiled code produced on one implementation of .NET (such as
Windows) could be moved to another implementation of .NET on a different
operating system merely by copying the compiled code over and running it.
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● Integrity with COM: .NET integrates very well with COM-based software. The
.NETFramework wraps COM components and exposes an interface that .NET
components canwork with. This is absolutely essential to the quick acceptance of
.NET, because it makes.NET interoperable with a tremendous amount of older
COM-based software. .NETprovides a possible solution to DLL Hell, and removes
much of the complexity of dealingwith COM and the registry..NET allows you to
run components locally without requiringthe calling application to go to the registry
to find components.
VB.NET Language
VB.Net is a simple, modern, object-oriented computer programming
language developed by Microsoft to combine the power of .NET Framework and
the common language runtime with the productivity benefits that are the hallmark
of Visual Basic.
Like all other .NET languages, VB.NET has complete support for objectoriented concepts. Everything in VB.NET is an object, including all of the
primitive types (Short, Integer, Long, String, Boolean, etc.) and user-defined
types, events, and even assemblies. All objects inherit from the base class Object.
VB.NET is implemented by Microsoft's .NET framework. Therefore, it has
full access to all the libraries in the .Net Framework. It's also possible to run
VB.NET programs on Mono, the open-source alternative to .NET, not only
under Windows, but even Linux or Mac OSX.
The following reasons make VB.Net a widely used professional language −
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● Modern, general purpose.
● Object oriented.
● Component oriented.
● Easy to learn.
● Structured language.
● It produces efficient programs.
● It can be compiled on a variety of computer platforms.
● Part of .Net Framework.
Simple VB.Net Program
A VB.Net program basically consists of the following parts:
● Namespace declaration
● A class or module
● One or more procedures
● Variables
● The Main procedure
● Statements & Expressions
● Comments
The following program displays the message “Hello World” in the Console
Window
Imports
System
Module
Module1
'This program will display Hello World
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Sub Main()
Console.WriteLine ("HelloWorld")
Console.ReadKey()
End Sub End Module
VARIABLES
Variable is a temporary storage location for data in your application. It can hold
the result of a specific calculation, information received from user at runtime
or piece of data that you want to display on a page
Variable naming conventions
● Variable name can contain digits, alphabets and the underscore character
● First character should not be a digit
● Keywords should not be used as variable name. However it can be used if
it is prefixed with the @ character
● Variable names are not case sensitive (i.e) variable names sum and Sum are treated
as same in Vb.NET
Variables can be declared in two ways
● Explicit Variable declaration
● Implicit Variable declaration
Explicit Variable declaration
Here we declare the variable explicitly by specifying variable name and type
after the Dim statement. It is strongly recommended method for variable declaration.
Syntax
Dim VariableName as Type [ = Initial value]
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Examples
Dim m, n as Single
Dim Fact as Integer = 1
Dim s as String
Dim p as Point = new Point(12,15)
Implicit Variable declaration
We can declare the variable implicitly that is simply by using the variable without
declaring it first.
Implicit variable declaration is not allowed by default. We have to place Option
Explicit Off at the top of the page to allow implicit variable declaration.
Example
Option Explicit Off
Public class Form1
Private sub form1_load(...)
s= “Hello”
MsgBox(s)
End sub
End Class
Another method is to use Option Infer Statement. If Option Infer is set to ON,
VB.NET will deduce or infer the type of variable by examining the assignment
you make.
Example
Dim a = 10
It is equivalent to Dim a as Integer=10
Implicit variable declaration is a risky method as it results in misspelled
variable name and other errors.
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CONSTANTS
Constant is a meaningful name that takes place of a number or text string that
does not change throughout the execution of a program.
Constants are declared with “const” keyword as follow
const PI as Double = 3.1415
Benefits of constants
● Increases the readability of code
● Makes global changes easier to accomplish
● Reduce programming mistakes
BOXING AND UNBOXING
Boxing and unboxing is an important concept in VB.NET's type system. With
Boxing and Unboxing, one can link between value-types and reference-types by
allowing any value-type to be converted to and from object type.
Boxing is a mechanism in which value type is converted into reference type. It
is implicit.
Unboxing is a mechanism in which reference type is converted into value type.
It is explicit conversion process.
Program to show Boxing and Unboxing
o=i
Module Module1
Sub Main()
Dim i As Integer = 10
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Dim j As Integer
Dim o As Object
' boxing'unboxing
j = CInt(o)
Console.WriteLine("Value of o object : " & o)
Console.WriteLine("Value of j : " & j)
Console.ReadLine()
End Sub
End Module
This example shows both boxing and unboxing. When a variable of a value type
needs to be converted to a reference type, an object box is allocated to hold the
value, and the value is copied into the box.
Unboxing is just the opposite. When an object box is cast back to its original
value type, the value is copied out of the box and into the appropriate storage
location.
DATA TYPES
Data types specify the size and type of values that can be stored. In Visual Basic,
data types are classified according to whether a variable of a particular type stores
its own data or a pointer to the data. If it stores its own data it is a value type; if it
holds a pointer to data elsewhere in memory it is a reference type.
`
Value Types
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A data type is a value type if it holds the data within its own memory allocation.
Value types are of fixed length and stored on the stack. Value types include the
following:
● All primitive data types
✔ Integer Types –sbyte, byte, short ,ushort, int, uint, long, ulong
✔ Floating point types – float, double, decimal
✔ Char type
✔ Boolean type
● Structures
● Enumerations
Integer Types
The Integer type is used to represent a whole number. Integer data types
include the following types.
Data Type
.Net Type Name
Size
Byte(unsigned)
System.Byte
8 bits
Short(signed)
System.Int16
16 bits
Integer(signed)
System.Int32
32 bits
Long(signed)
System.Int64
64 bits
SByte(signed)
System.Sbyte
8 bits
Short(unsigned)
System.Uint16
16 bits
UInteger(unsigned)
System.Uint32
32 bits
ULong(unsigned)
System.Uint64
64 bits
Floating point types
It is used to represent fractional values. Floating point data types includes the
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following types
Data Type
.Net Type Name
Size
Single
System.Single
32 bits
Double
System.Double
64 bits
Decimal
System.Decimal 128 bits
Single Type
It is used to represent a fractional number with seven decimal digits of precision.
Append F to treat numeric literal as Single.
Double Type
It is used to represent a fractional number with 15 decimal digits of precision.
Append R to treat numeric literal as Double.
Decimal Type
It is more precise than single or double. It has 28 decimal digits of precision.
Append D to treat numeric literal as Decimal.
Char Type
It is used to represent a single Unicode character. It is of 2 bytes in length.
Append c when initializing a char
Boolean Type
Boolean type represents the Boolean value true or false. It is assigned 16 bits.
Structure Type
The structure data type is used to define a composite date type.
Defining a Structure
Public Structure Point
Dim x as Integer
Dim x as Integer
End Structure
Accessing a Structure
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Dim p as Point
p.x=100
p.y=200
Enum Type
The Enum type is used to represent a set of named constants
Example
Enum Direction
West
East
North
South
End Enum
Reference Type
A reference type contains a pointer to another memory location that holds the data.
Reference types are of variable length and stored on the heap. Reference types
include the following:
● Object
● String
● Class
● Interface
● Delegate
● Arrays
Object Type
The Object type is a predefined referenced type. It serves as the base class for all
predefined and user defined classes.
String Type
The String type is also a predefined reference type. It is used for creating and
manipulating strings. We can perform various operations on string, such as
copying, comparing, searching, concatenating and so on.
Classes
Classes provide the best approach to group together the logically related items and
functions that work on them
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Interface
Interfaces are a collection of members, such as methods, delegates, events and
Properties which are to be implemented by classes
Delegates
Delegates are used to encapsulate a method with a specific signature. It is similar to
function pointer in c++
Arrays
Arrays are used to store a fixed size sequential collection of elements of same
type.
Value type
Reference type
Value type store real data
Reference type store reference to the
data.
Value type are stored on stack of
memory
Reference type are stored on heap of
memory
When passed as value type, new copy is When passed as Reference type then
created and passed. So changes to
reference of that variable is passed. So
variable does not getreflected back
changes to variable does get reflected back
Value types are faster in access
Reference types are slower in access.
Value type consists of primitive
data types, structures,
enumerations.
Reference type consists of class, array,
interface, delegates
Value types derive
from System.ValueType
Reference types derive
from System.Object
Value types cannot contain the
value null.
Reference types can contain the value
null.
Example:
Module DataTypes
Sub Main()
Dim b As Byte
Dim n As Integer
Dim si As Single
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Dim d As Double
Dim da As Date
Dim c As Char
Dim s As String
Dim bl As Boolean
b=1
n = 1234567
si = 0.12345678901234566
d = 0.12345678901234566
da = Today
c = "U"c
s = "Me"
If ScriptEngine = "VB" Then
bl = True
Else
bl = False
End If
If bl Then
'the oath taking
Console.Write(c & " and," & s & vbCrLf)
Console.WriteLine("declaring on the day of: {0}", da)
Console.WriteLine("We will learn VB.Net seriously")
Console.WriteLine("Lets see what happens to the floating point variables:")
Console.WriteLine("The Single: {0}, The Double: {1}", si, d)
End If
Console.ReadKey()
End Sub
End Module
When the above code is compiled and executed, it produces the following result
−
U and, Me
declaring on the day of: 12/4/2012 12:00:00 PM
We will learn VB.Net seriously
Lets see what happens to the floating point variables:
The Single:0.1234568, The Double: 0.123456789012346
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OPERATORS
An operator is a symbol that tells the compiler to perform specific mathematical or
logical manipulations. VB.Net is rich in built-in operators and provides following
types of commonly used operators:
● Arithmetic Operators
● Comparison Operators
● Logical/Bitwise Operators
● Bit Shift Operators
● Assignment Operators
● Concatenation Operators
Arithmetic Operators
Arithmetic operators are used in mathematical expressions. The following table
lists the arithmetic operators:
Assume integer variable A holds 5 and variable B holds 2, then:
Operator
Description
Example
+
Addition
A + B will give 7
-
Subtraction
A - B will give 3
*
Multiplication
A * B will give 10
/
Division
A / B will give 2.5
\
Integer Division(Whole No Division)
A \ B will give 2
Remainder Division
A mod B will give 1
Exponentiation(Raising to a power)
A ^ B will 25
Mod
^
Comparison Operators
Following table shows all the comparison operators supported by VB.Net.
Assume variable A holds 10 and variable B holds 20, then
Operator
=
Description
Equal to
Example
A = B will give false
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<>
Not Equal to
A <> B will give true
<
Less than
A < B will give true
>
Greater Than
A > B will give false
<=
Less than equal to
A <= B will give true
>=
Greater than equal to
A >= B will give false
Logical/Bitwise Operators
Bitwise operator works on bits and performs bit-by-bit operation. Following
table shows all the logical operators supported by VB.Net.
Assume variable A holds Boolean value True and variable B holds Boolean
value False, then
Operator
Description
Example
NOT
Logical as well as bitwise negation
operator
NOT A will give false
AND
Logical as well as bitwise
Conjunction operator
A AND B will
giveFalse
OR
Logical as well as bitwise
disjunction operator
A OR B will give true
XOR
Logical as well as bitwise exclusion
operator
A XOR B will
givetrue
AndAlso
Short Circuiting Logical Conjunction
operator
A AndAlso B will give
False
OrElse
Short Circuiting Logical Disjunction
operator
A OrElse B will give
true
Truth Table for logical operator
A
B
Not A
A and B
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A Or B
A Xor B
False
False
True
False
False
False
False
True
True
False
True
True
True
False
False
False
True
True
True
True
False
True
True
False
AndAlso
When the left hand side is false, the condition of right hand side is never
Evaluated
A
B
A AndAlso B
False
Never Evaluated
False
True
False
False
True
True
True
OrElse
When the left hand side is true, the condition of right hand side is never
Evaluated.
A
B
A AndAlso B
True
Never Evaluated
True
False
True
True
False
False
False
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Bit Shift Operator
There are two bit shift operators. They are,
<< - Bit Shift Left Operator
>> - Bit Shift Left Operator
Concatenation Operator
Concatenation Operators are used to join multiple strings into a single string.
There are two concatenation operator namely “+” and “&”
Assignment Operator
Operation
Long form syntax
Shortcut Syntax
Addition
x=x+6
x += 6
Subtraction
x=x-6
x -= 6
Multiplication
x=x*6
x *= 6
Division
x=x/6
x /= 6
Integer Division
x=x\6
x \= 6
Exponentiation
x=x^6
x ^= 6
String
Concatenation
x = x & “abc”
x &= “abc”
Operator Precedence
Operator precedence determines the grouping of terms in an expression. This
affects how an expression is evaluated. Operators with the highest precedence
appear at the top of the table, those with the lowest appear at the bottom.
Within an expression, higher precedence operators will be evaluated first
Operator
Precedence
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() Parenthesis
^ Exponentiation
- Unary negation
*,/
/ Integer division
Mod
+,<< , >>
All comparison operators (=, <>, <, <=, >, >=)
Not
And, AndAlso
Or, OrElse
Highest
Xor
Lowest
Controls in Windows Forms
Control Class
The control class is the ultimate base class for all Windows Forms controls.
This class implements base functionalities, such as handling user input through
keyboard and mouse and defining position and size of a control that displays
information to the user. It is defined in the namespace
System.Windows.Forms namespace.
The Control class defines properties, methods, and events, which are common
to all Windows Forms controls
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Some Properties of Control class
● Font : Gets or sets the font of the text displayed by the control.
● BackColor : Gets or sets the background color for the control.
● ForeColor : Gets or sets the foreground color of the control
● Margin : Gets or sets the space between controls.
● Size : Gets or sets the height and width of the control.
● Dock : Gets or sets which control borders are docked to its parent control and
determines how a control is resized with its parent.
● Text : Gets or sets the text associated with this control.
● Visible : Gets or sets a value indicating whether the control and all its child
controls are displayed.
● Enabled : Gets or sets a value indicating whether the control can respond to user
interaction.
● Parent : Gets or sets the parent container of the control
Some methods of Control class
● Hide() : Conceals the control from the user
● Show() : Displays the control to the user.
● Focus() : Sets input focus to the control.
● Select() : Activates the control.
Some Events of Control class
● Click : Occurs when the control is clicked.
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● DoubleClick : Occurs when the control is double-clicked.
● GotFocus : Occurs when the control receives focus.
● LostFocus : Occurs when the control loses focus.
● KeyDown : Occurs when a key is pressed down while the control has focus.
● KeyPress : Occurs when a key is pressed while the control has focus.
● KeyUp : Occurs when a key is released while the control has focus.
Label Control
The Label control is one of the most commonly used windows Form controls. Label
controls are typically used to provide descriptive text for a control. For example, you
can use a Label to add descriptive text for a TextBox control to
inform the user about the type of data expected in the control.
Label is a non selectable control. Unlike other controls, it is not meant to
accept input from user. Instead it displays a text that user can view but not
select or modify.
Some Properties of Label
● BorderStyle : Gets or sets the border style for the control.
● Image : Gets or sets the image that is displayed on a Label.
● ImageAlign : Gets or sets the alignment of an image that is displayed in
the control.
● Text : Gets or sets the text associated with this control.
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● TextAlign : Gets or sets the alignment of text in the label.
TextBox Control
TextBox control lets you enter text on a Windows form at runtime.
Typically, itis used to display or accept a single line of text. You can use the
Multiline andScrollBars properties to enable multiple lines of text to be displayed or
entered.Set the AcceptsTab and AcceptsReturn properties to true to enable greater
textmanipulation in a multiline TextBox control. It can also be used to
acceptpasswords and other sensitive information. You can use the PasswordChar
property to mask characters entered in the TextBox
You can limit the amount of text entered into a TextBox control by setting the
MaxLength property to a specific number of characters. Use the CharacterCasing
property to enable the user to type only uppercase, only lowercase, or a combination
of uppercase and lowercase characters into theTextBox control.
Some Properties of TextBox
● Multiline : Gets or sets a value indicating whether this is a multiline
TextBox control.
● AcceptsReturn : Gets or sets a value indicating whether pressing ENTER in a
multiline TextBox control creates a new line of text in the control
● AcceptsTab : Gets or sets a value indicating whether pressing the TAB key in a
multiline text box control types a TAB character in the control instead of moving the
focus to the next control in the tab order
● PasswordChar : Gets or sets the character used to mask characters of
a password in a single-line TextBox control
● Text : Gets or sets the current text in the TextBox.
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● SelectedText : Gets or sets a value indicating the currently selected text
in the control
● CharacterCasing : Gets or sets whether the TextBox control modifies
the case of characters as they are typed. The possible values are :Lower,
Normal or Upper
● ReadOnly : Gets or sets a value indicating whether text in the text box
is read-only
Some Methods of TextBox
● Clear() - Clears all text from the text box control.
● Copy() - Copies the current selection in the text box to the Clipboard.
● Cut() - Moves the current selection in the text box to the Clipboard
● Paste() - Replaces the current selection in the text box with the contents
of the Clipboard.
● SelectAll() - Selects all text in the text box.
● Undo() - Undoes the last edit operation in the text box
● Focus() - Sets input focus to the control
Important Event of TextBox
● TextChanged : Occurs when the Text property value changes.
Button Control
Buton control lets you generate a Click event; by handling the click event of a
button, you can make the user perform some action at the runtime. A Button
can be clicked by using the mouse, ENTER key, or SPACEBAR if the button
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has focus.
Some Properties of Button
● Image : Gets or sets the image that is displayed on a button control.
● ImageAlign : Gets or sets the alignment of the image on the button
Control
● Text : Gets or sets the text associated with this control.
● TextAlign : Gets or sets the alignment of the text on the button control.
Important event of Button
● Click : Occurs when the
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