ASP.NET - UNIT 1

SYLLABUS :

UNIT I : ASP.NET Basics Introduction to ASP.NET: .NET Framework (CLR, CLI, BCL), ASP.NET Basics, ASP.NET Page Structure, Page Life Cycle. Controls: HTML Server Controls, Web Server Controls, Web User Controls, Validation Controls, Custom Web Controls.

1.1 INTRODUCTION TO .NET Framework

The .NET Framework is a software framework developed by Microsoft. The .NET runs on Microsoft Windows. It provides language interoperability and can run across several programming languages and platforms. Programs written for the .NET Framework execute in a software environment, known as the Common Language Runtime (CLR). CLR is an application virtual machine that provides services such as security, memory management, and exception handling. The class libraries and the CLR together constitute the .NET Framework.

The .NET Framework's Base Class Library provides user interface, data access, database connectivity, cryptography, web application development, numeric algorithms, and network communications.

1.2 DESIGN FEATURES OF .NET

• Interoperability .NET Framework provides access to newer and older programs that execute outside the .NET environment. Access to COM components is provided in the System.Runtime.
• Common Language Runtime engine Common Language Runtime (CLR) serves as the execution engine of the .NET Framework. All .NET programs execute under the supervision of the CLR, guaranteeing certain properties and behaviors in the areas of memory management, security and exception handling.
• Language independence The .NET Framework has Common Type System(CTS). CTS is used to support all datatypes and programming constructs supported by the CLR Because of CTS, the .NET Framework supports the exchange of types and object instances between libraries and applications written using any conforming .NET language.
• Base Class Library The Base Class Library (BCL), is part of the Framework Class Library (FCL). It is a library of functionality available to all languages using the .NET Framework. The BCL provides classes that encapsulate a number of common functions, including file reading and writing, graphic rendering, database interaction, XML document manipulation, and so on. It consists of classes, interfaces of reusable types that integrates with CLR.
• Simplified deployment The .NET Framework includes design features and tools which help manage the installation of computer software to ensure it does not interfere with previously installed software.
• Security .NET provides a common security model for all applications. It eliminates the vulnerabilities, such as buffer overflows, which have been exploited by malicious software. Additionally,
• Portability .NET framework is platform independent and cross-platform implementations are available for other operating systems.

1.3 EVOLUTION OF .NET

Framework	Versions /Tools used	Features
.NET Framework 1.0 (February 2002)		First version of .NET Framework.
.NET Framework 1.1 (April 2003)	C# Version: 1.2 CLR Version: 1.1	· ASP.NET and ADO.NET updates · Side by side execution · .NET Compact framework · Secure coding guideline · Information about application deployment
.NET Framework 2.0 (November 2003)	C# Version: 2.0 CLR Version: 2.0 Development Tool : Visual Studio 2005	· 64-bit platform support · Access Control List Support · Data Protection APIs · Detecting changes in network connectivity · FTP Support · Web Services
.NET Framework 3.0 (November 2006)	C# Version: 3.0 CLR Ver: 2.0 Dev Tool: Visual Studio 2005	· Windows Communication Foundation · Windows Presentation Foundation · Windows Forms
.NET Framework 3.5 (November 2007)	C# Version: 3.0 CLR Version: 2.0 Development Tool : Visual Studio 2008	· ASP.NET Ajax enabled Websites · LINQ · Dynamic DataCollections · Time Zone Improvements · Cryptography Enhancements · Web Service interoperability
.NET Framework 4.0 (April 2010)	C# Version: 4.0 CLR Version: 4 Development Tool : Visual Studio 2010	· Expanded Base Class · Cross-Platform Development with portable class library · Dynamic Language Runtime · Parallel Computing
.NET Framework 4.6 (July 2015)	C# Version: 6.0 CLR Version: 4.0 Development Tool : Visual Studio 2015	· Compilation Using .NET Native · ASP.NET Core 5 · HTTP/2 Support · 64-bit JIT Compiler for managed code · SSL Support
.NET Framework 4.7 (April 2017)	C# Version: CLR Version: 4.0 Development Tool : Visual Studio 2017	· Enhanced cryptography with elliptic curve cryptography. · Support for High-DPI awareness support in Windows Forms. · More support for touch and stylus in Windows Presentation Foundation.
.NET Framework 4.8 (April 2019)	C# Version: CLR Version: 4.0 Development Tool : Visual Studio 2019	· Runtime – JIT improvements. · Runtime – Antimalware Scanning. · Windows Forms – Accessibility Enhancements.

Table 1 : Evolution of .NET (Reference Wikipedia)

1.4 COMMON LANGUAGE INFRASTRUCTURE (CLI)

Common Language Infrastructure (CLI) provides a language-neutral platform for application development and execution, including functions for Exception handling, Garbage Collection, security, and interoperability.

By using the features of the .NET Framework within the scope of the CLI, the functionality will be available across all the languages supported by the framework. Microsoft's implementation of the CLI is called the Common Language Runtime, or CLR.

The CIL code is housed in CLI assemblies. CLI assemblies are stored in the Portable Executable (PE) format for all DLL and EXE files.

The complete name of an assembly contains its simple text name, version number, culture, and public key token. Assemblies are considered equivalent if they share the same complete name, excluding the revision of the version number.

1.5 . ASP.NET

ASP.NET, the next version of ASP, is a programming framework used to create enterprise-class Web Applications. These applications are accessible on a global basis leading to efficient information management.

1.6 Advantages of using ASP.NET

• ASP.NET reduces the amount of code required to build large applications ASP.NET applications runs faster and counters large volumes of users without performance problems.
• ASP.NET makes development simpler and easier to maintain with an event-driven, server-side programming model
• ASP.NET pages are easy to write and maintain because the source code and HTML are together.
• The source code which is executed in the server is compiled the first time the page is requested. Execution is fast as the Web Server compiles the page the first time it is requested. The server saves the compiled version of the page for use next time the page is requested .
• The HTML produced by the ASP.NET page is sent back to the browser. The application source code is not sent and is not easily stolen .
• ASP.NET facilitates for easy deployment. There is no need to register components because the configuration information is built-in.
• The Web server continuously monitors the pages, components and applications running on it. If it notices memory leaks, infinite loops, other illegal software or activities, it seamlessly kills those activities and restarts itself.
• ASP.NET validates information (validation controls) entered by the user without writing a single line of code.
• ASP.NET works with ADO .NET for connecting to databases and data-binding.

1.7 DIFFERENCES BETWEEN ASP.NET AND CLIENT-SIDE TECHNOLOGIES

Client-side refers to browser and the machine running the browser. Server-side refers to Web server.

Client-Side Scripting JavaScript and VBScript are generally used for Client-side scripting and it is executed in the browser after the page is loaded. Both, HTML and the script are together in the same file and the script is downloaded as part of the page. A client-side script runs only on a browser that supports scripting and specifically the scripting language that is used. Since the script is in the same file as the HTML and as it executes on the machine you use, the page may take longer time to download.

Server-Side Scripting ASP.NET is purely server-side technology. ASP.NET code executes on the server before it is sent to the browser. The code that is sent back to the browser is pure HTML and not ASP.NET code. Like client-side scripting, ASP.NET code is written alongside HTML. Unlike client-side scripting, ASP.NET code is executed in server and not in the browser. The script that is present along with HTML is not sent back to the browser and that prevents others from stealing the code.

1.8 FEATURES OF ASP.NET

• ASPX,ASP Up gradation of ASP to ASPX is not required it supports side by side execution and hence a request can be given from ASP to ASPX and vice versa.
• Simplified Programming Model ASP.Net is a technology which can be implemented using any dot net language such as VB.net,C# etc and hence there is no requirement of HTML, JavaScript or VBScript to implement ASP.NET
• Simplified deployment ASP.Net supports setup and deployment and hence the web app can be defined with a web set up project which can be easily deployed on to the web server. In for ASP CUTE FTP is used for deploying, it is required to upload manually.
• Better Performance Since ASPX pages are complier based the performance of the web application will be faster than the ASP pages (as they are interpreter based)
• Caching It is a process of maintaining the result or output of a web page temporarily for some period of time .ASP supports Client Side caching where as ASP.Net supports both client side and server side.
• Security In ASP security is done by IIS or writing the code manually. In ASP.Net it is defined with built in security features such as

* windows authentication * Forms Authentication

* Passport Authentication * Custom Authentication

• More powerful data access ASP.net supports ADO and ADO.Net as its database connectivity model which will be implemented using the most Powerful OOP’S languages like VB.Net and C# and hence the database access using ASPX pages will be very powerful.
• Web services It is a code which will be published on the web which can be used by any applications written using any language for an platform or device.
• Better session Management Session Management in ASP.Net can be maintained using the database and cookieless sessions are also supported. It also supports enabling and disabling of session info within a web application.
• Simplified Form Validations ASP.Net provides validation controls using which any type of client side validations are performed without writing any code.

1.9 ARCHITECTURE OF ASP.NET

A web page is in 2 parts

1} Designing part (HTML Content,Flash,Dreamweaver etc)

2} logic Part (sub programs and event procedures and it has also your database interaction)

ASP.Net supports 2 techniques for creating web page

1) In Page Technique when you place design part code and logic part code with in a single file called as ASPX then it is called as inPage Technique.

2) Code Behind Technique when design part code is represented with in ASPX file and logic part code is represented with in dll file then it is called as code behind technique.

ASP Supports only In Page technique.

DLL file is not a readable file so it is secured.

• Inet_info.exe à identifies the request and submits the request to the aspnet_isapi.dll.
• Aspnet_isapi.dll à is a script engine which process the .aspx page
• Then the script engine will submit the request to the ASP.NET runtime env.
• After verifying all the security issues of both machine.config and web.config then an AppDomain will be defined for the request and after processing the request the response will be given to the client as HTTP response.
• Machine.Config à it is used to maintain the complete configuration details of all the web applications registered on to the web server of ASP.net
• Web.Config à It is used to maintain the config details about a single web application.
• Configuration details includes security, database connectivity, state management, trace details of the web application, authentication and authorization of the applications and globalizations.
• AppDomain: All windows applications run inside a process and these process own resources such as memory and kernel objects. All the applications are run on high isolation mode to work safely. The disadvantage of this is memory resources are blocked. So to achieve this in a single process all the applications should be made to run which is good to an extent. In .net the code verification feature takes care that the code is safe to run, so asp.net each application runs its own application domain.
• HTTPHandlers: ASP.net is built on extensible architecture known as HTTP runtime. This is responsible for handling the requests and sending the response. IS supports a low level API known as ISAPI. ASP.net implements a similar concept with HTTP handlers. A request is assigned to ASP.net from IIS then ASP.net examines entries in the <httphandlers> section based on the extension of the request to determine which handler the request should be send to.

1.10 The Structure of an ASP.NET Page

The important elements of an ASP.NET page are:

· Directives

· Code declaration blocks

· ASP.NET controls

· Code render blocks

· Server-side comments

· Server-side include directives

· Literal text and HTML tags

Directives A directive controls the compilation of ASP.NET. The directive begins with the characters <%@ and the end of a directive is marked with the characters %>. These instructions include registering a custom control, page language etc. It describes how the .aspx pages (web forms) or .ascx pages (user controls) are processed by the .net framework.

A directive can appear anywhere within a page. By convention, however, a directive typically appears at the top of an ASP.NET page.

There are several types of directives that can be added to an ASP.NET page. Two of the most useful types are page and import directives.

Page Directives A page directive is used to specify the default programming language for a page. Page directives can also be used to enable tracing and debugging for a page.

To change the default programming language of an ASP.NET page from Visual Basic to C#, for example, you would use the following page directive:

<%@ Page Language="C#" %>

NOTE : The keyword Page in a page directive is optional. The following two directives are equivalent: <%@ Page Language="C#" %>

<%@ Language="C#" %>

TRACE DIRECTIVE : If Trace directive is enabled, for a page, additional information about the execution of the page is displayed along with the content of the page. Tracing can be enabled for a page by including the following directive:

<%@ Page Trace="True" %>

After enabling tracing for a page, trace messages can be displayed by using two methods of the Trace class: Write() and Warn(). Either of these methods can be used to display custom message in the trace information displayed at the bottom of the page. The only difference between the two methods is that the former method displays messages in black text, and the latter method displays messages in red text, which is easier to see.

DEBUG DIRECTIVE To enable runtime error messages to be displayed on a page, the Debug directive is used. To display errors in ASP.NET page, the following directive is included:

<%@ Page Debug="True" %>

If this directive is included, when an error is encountered while processing the page, the error is displayed. In most cases, we can view source code for the exact statement that generated the error.

To enable both tracing and debugging for a page, combine the directives like this.

<%@ Page Debug="True" Trace="True" %>

IMPORT DIRECTIVES By default, only certain namespaces are automatically imported into ASP.NET page. Inorder to refer to a class that isn't a member of one of the default namespaces, the namespace must be explicitly imported or t use the fully qualified name of the class.

For example, to send an email from an ASP.NET page by using the Send method of the SmtpMail class, SmtpMail class is to added as an Import directive. The SmtpMail class is contained in the System.Web.Mail namespace. This is not a default namespace imported into an ASP.NET page.

The following page shows how to import the System.Web.Mail namespace and send email message.

ImportNamespace.aspx

<%@ Import Namespace="System.Web.Mail" %>

<Script Runat="Server">

Sub Page_Load

Dim mailMessage As SmtpMail

mailMessage.Send( "bob@somewhere.com", "Sending Mail!", "Hello!" )

End Sub

</Script>

<html>

<head><title>ImportNamespace.aspx</title></head>

<body>

<h2>Email Sent!</h2>

</body>

</html>

The first line in the above Listing contains an import directive. Without the import directive, the page would generate an error because it would not be able to resolve the SmtpMail class.

@ assembly The @assembly directive attaches assemblies to the page or an asp.net user control thereby all the assembly classes and interfaces are available to the class. This directive supports the two attributes name and src. The name attribute defines the assembly name and the src attribute defines the source of the assembly.

@ control Defines control-specific attributes used by the asp.net page parser and compiler and can be included only in .ascx files (user controls).

@ implements The @implements directive gets the asp.net pages to implement .net framework interfaces. This directive only supports a single attribute interface.

@ master Identifies a page as a master page and defines attributes used by the asp.net page parser and compiler and can be included only in .master files.

@ page The @page directive enables you to specify attributes and values for an asp.net page to be used when the page is parsed and compiled. Every .aspx files should include this @page directive to execute. There are many attributes belong to this directive.

@ reference Links a page, user control, or com control to the current page or user control declaratively.

@ register Associates aliases with namespaces and classes, which allow user controls and custom server controls to be rendered when included in a requested page or user control.

CODE DECLARATION BLOCKS A code declaration block contains all the application logic for your ASP.NET page and all the global variable declarations, subroutines, and functions. It must appear within a <Script Runat="Server"> tag.

Codefile specifies a path to the referenced code-behind file for the page. Inherits defines the name of the class from which to inherit. This can be any class derived from the page class

1.11 Page Life Cycle Events

• Page_Init This is fired when the page is initialized
• Page_Load This is fired when the page is loaded.

The difference between Page_Init and Page_load is that the controls are guaranteed to be fully loaded in the Page_load.The controls are accessible in the Page_Init event,but the ViewState is not loaded,so controls will have their default values,rather than any values set during the postback.

• Control_Event This is fired if a control triggered the page to be reloaded (such as a button)
• Page_unload This is fired when the page is unloaded from the memory

1.12. TYPES OF CONTROLS IN ASP.NET

1.12.1 HTML Server Controls

HTML elements in ASP.NET files are, by default, treated as text. To make these elements programmable, add a runat="server" attribute to the HTML element. This attribute indicates that the element should be treated as a server control.

Note: All HTML server controls must be within a <form> tag with the runat="server" attribute!, ASP.NET requires that all HTML elements must be properly closed and properly nested.

SYNTAX

<INPUT TYPE=TEXT RUNAT=SERVER>

HTML Server Control	Description
HtmlAnchor	Controls an <a> HTML tag
HtmlButton	Controls a <button> HTML tag
HtmlForm	Controls a <form> HTML tag
HtmlImage	Controls an <image> HTML tag
HtmlInputButton	Controls <input type="button">, <input type="submit">, and <input type="reset"> HTML tags
HtmlInputCheckBox	Controls an <input type="checkbox"> HTML tag
HtmlInputFile	Controls an <input type="file"> HTML tag
HtmlInputHidden	Controls an <input type="hidden"> HTML tag
HtmlInputImage	Controls an <input type="image"> HTML tag
HtmlInputRadioButton	Controls an <input type="radio"> HTML tag
HtmlInputText	Controls <input type="text"> and <input type="password"> HTML tags
HtmlSelect	Controls a <select> HTML tag
HtmlTable	Controls a <table> HTML tag
HtmlTableCell	Controls <td>and <th> HTML tags
HtmlTableRow	Controls a <tr> HTML tag
HtmlTextArea	Controls a <textarea> HTML tag

1.12.2 WEBSERVER CONTROLS

Web server controls are special ASP.NET tags understood by the server. Like HTML server controls, Web server controls are also created on the server and they require a runat="server" attribute to work.

Standard Controls	List Controls	Validation Controls	Data bound Controls	Misc Controls
§ label § Textbox § Button § Link Button § Image Button § Calendar § AdRotator § Panel § Place Holder § Table § Literal Control § Radio Button § Check Box § XML	§ Radio Button List § Check Box List § Dropdown List § List Box	1. Required field Validator 2. Range Validator 3. Compare Validator 4. Regular Expression Validator 5. Custom Validator 6. Validation Summary	§ Data Grid § Data List § Repeater	§ Crystal Report Viewer control

Common Syntax for any web server control

• <asp:controltype id=“name of the control” runat=“server”
  ----------------
  ----------------
  //additional properties
  ></asp:controltype>

• In order to set or get the value from any standard control text property should be used.

Eg: <asp:label id=“lb1” runat=“server” text=“user name”></asp:label>

<asp:button id=“lb1” runat=“server” text=“Login” />

Web Server Control	Description
AdRotator	Displays a sequence of images
Button	Displays a push button
Calendar	Displays a calendar
CheckBox	Displays a check box
CheckBoxList	Creates a multi-selection check box group
DataGrid	Displays fields of a data source in a grid
DataList	Displays items from a data source by using templates
DropDownList	Creates a drop-down list
HyperLink	Creates a hyperlink
Image	Displays an image
ImageButton	Displays a clickable image
Label	Displays static content which is programmable
LinkButton	Creates a hyperlink button
ListBox	Creates a single- or multi-selection drop-down list
ListItem	Creates an item in a list
Literal	Displays static content which is programmable
Panel	Provides a container for other controls
PlaceHolder	Reserves space for controls added by code
RadioButton	Creates a radio button
RadioButtonList	Creates a group of radio buttons
BulletedList	Creates a list in bullet format
Repeater	Displays a repeated list of items bound to the control
Style	Sets the style of controls
Table	Creates a table
TableCell	Creates a table cell
TableRow	Creates a table row
TextBox	Creates a text box

1.12.3 TEXTBOX

TextBox is a server side control. It is an input control which is used to take user input.

The asp tag to create TextBox is:

< asp:TextBoxID="TextBox1" runat="server" ></asp:TextBox>

Notable Properties of TextBox are :

AccessKey : It is used to set keyboard shortcut for the control.

TabIndex : The tab order of the control.

BackColor : It is used to set background color of the control.

BorderColor : It is used to set border color of the control.

BorderWidth : It is used to set width of border of the control.

Font : It is used to set font for the control text.

Text : It is used to set text to be shown for the control.

ToolTip : It displays the text when mouse is over the control.

Visible : To set visibility of control on the form.

Height : It is used to set height of the control.

Width : It is used to set width of the control.

MaxLength : It is used to set maximum number of characters that can be entered.

1.12.4 BUTTON

Buttons control is a server side control and is used to perform events. It is used to submit client request to the server.

The asp tag to create Button is:

< asp:ButtonID="Button1" runat="server" Text="Submit" BorderStyle="Solid" ToolTip="Submit"/>

Notable Properties of Button are :

AccessKey : It is used to set keyboard shortcut for the control.

TabIndex : The tab order of the control.

BackColor : It is used to set background color of the control.

BorderColor : It is used to set border color of the control.

BorderWidth : It is used to set width of border of the control.

Font : It is used to set font for the control text.

ForeColor : It is used to set color of the control text.

Text : It is used to set text to be shown for the control.

ToolTip : It displays the text when mouse is over the control.

Visible : To set visibility of control on the form.

Height : It is used to set height of the control.

Width : It is used to set width of the control.

1.12.5 LABEL

Label control is used to display textual information on the web forms. It is mainly used to create caption for the other controls like textbox.

The asp tag to create Label is:

< asp:LabelID="Label1" runat="server" Text="Label" ></asp:Label>

Notable Properties of Label are :

AccessKey : It is used to set keyboard shortcut for the label.

TabIndex : The tab order of the control.

BackColor : It is used to set background color of the label.

BorderColor : It is used to set border color of the label.

BorderWidth : It is used to set width of border of the label.

Font : It is used to set font for the label text.

ForeColor : It is used to set color of the label text.

Text : It is used to set text to be shown for the label.

ToolTip : It displays the text when mouse is over the label.

Visible : To set visibility of control on the form.

Height : It is used to set height of the control.

Width : It is used to set width of the control.

1.12.6 RadioButtonList The RadioButtonList Web server control is used to display a list of radio buttons. This control provides with a single-selection radio button group that can be dynamically generated via data binding. The Items property of this control allows us to add items to the control. To determine which item is selected, the SelectedItem property of the list is used.

RadioButtonList event : The default event of the RadioButtonList is the SelectedIndexChanged which looks like this in code:

Private Sub RadioButtonList1_SelectedIndexChanged(ByVal sender As System.Object,_ByVal e As System.EventArgs) Handles RadioButtonList1.SelectedIndexChanged

End Sub

Notable properties of the RadioButtonList control are as follows:

Items : Gets/Sets the collection of items in the list

RepeatColumns : Gets/Sets the number of displayed columns in the radio button list

RepeatDirection : Gets/Sets the display direction of radio buttons

RepeatLayout : Gets/Sets the radio button layout

TextAlign : Gets/Sets the radio button's text alignment

RadioButtonListSample

The following code will displayed after adding some items to the radio button

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
TextBox1.Text = RadioButtonList1.SelectedItem.Text
End Sub

5. CheckBoxList The CheckBoxList Web server control displays a number of checkboxes at once. This control provides a multi selection check box group that can be dynamically generated with data binding. It contains an Items collection with members that correspond to individual items in the list. To determine which items are checked, we need to test the Selected property of each item in the list.

Notable properties of the CheckBoxList control are as follows:

Items : Gets/Sets the collection of items in the list

RepeatColumns : Gets/Sets the number of displayed columns in the check box list

RepeatDirection : Gets/Sets the display direction of checkboxes

RepeatLayout : Gets/Sets the checkbox layout

TextAlign : Gets/Sets the check box's text alignment

CheckBoxList Sample

Drag a CheckBoxList, TextBox and a Button on to the form. Select the CheckBoxList and add some items to it using the Items property. The following code will display the text of the checkbox that is checked in the textbox when the button is clicked.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
TextBox1.Text = CheckboxList1.SelectedItem.Text
End Sub

1.13 SAMPLE ASP.NET PROGRAM (Using TextBox, RadioButton, Button):

Aim : To choose sex of a candidate from radiobutton, Read age of the candidate from a textbox and determine, whether the candidate is eligible for marriage.

<%@ Page Language="VB" CodeFile="Default.aspx.vb" %>

<html>

<head runat="server">

<title>Untitled Page</title>

</head>

<body>

<form id="form1" runat="server">

<div>

<asp:TextBox ID="TextBox1" runat="server" Style="left: 296px; position: absolute; top: 80px" Width="24px"></asp:TextBox>

<asp:TextBox ID="TextBox2" runat="server" Style="left: 160px; position: absolute; top: 216px" Width="216px"> </asp:TextBox>

<asp:Label ID="Label1" runat="server" Style= "left: 264px; position: absolute; top: 80px" Text="Age"> </asp:Label>

<asp:Label ID="Label2" runat="server" Style= "left: 8px; position: absolute; top: 80px" Text="Sex"> </asp:Label>

<asp:RadioButton ID="RadioButton1" runat="server" Style="left: 0px; position: absolute; top: 112px" Text="Male" />

<asp:RadioButton ID="RadioButton2" runat="server" Style="left: 0px; position: absolute; top: 144px" Text="Female" />

<asp:Button ID="Button1" runat="server" Style="left: 88px; position: absolute;top: 216px" Text="CHECK" />

</div>

</form>

</body>

</html>

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

If RadioButton1.Checked = True And Val(TextBox1.Text) > 24 Then

TextBox2.Text = "ELIGIBLE FOR MARRIAGE"

Else

TextBox2.Text = "NOT ELIGIBLE FOR MARRIAGE"

End If

If RadioButton2.Checked = True And Val(TextBox1.Text) > 21 Then

TextBox2.Text = "ELIGIBLE FOR MARRIAGE"

Else

TextBox2.Text = "NOT ELIGIBLE FOR MARRIAGE"

End If

RadioButton1.Checked = False

RadioButton2.Checked = False

End Sub