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Use this step-by-step guide to set up a breakpoint, use

page-level tracing, and write out custom trace messages in an ASP.NET

application.

The new debugging features in ASP.NET allow you to

track progress through your Web applications and more easily identify and

diagnose problems.

Requirements

The

following list outlines the recommended hardware, software, network

infrastructure, and service packs that you need:Microsoft Visual Studio .NETMicrosoft Internet Information Services (IIS)

5.0This

article assumes that you are familiar with the following topics:

Web applicationsMicrosoft ASP.NET

Overview

Debugging a traditional ASP application generally involves

placing Response.Write statements throughout your code to track variable values and

execution paths. If you fail to remove debugging statements before you deploy

your application, the statements are visible to users.

ASP.NET makes

Web application debugging much simpler to use. You can use tracing statements

to debug your application in a way that is similar to using Response.Write statements. However, you can leave the tracing statements in your

application, even after deployment.

You can configure the Web

application to allow tracing at either the page level or the application level,

and you can easily turn it on and off. You can also control the destination of

the tracing output to allow only certain users to see the debugging output.

Create an ASP.NET application and add breakpoints to debug the application

The following procedure creates a simple ASP.NET Web application

that performs a calculation on two numbers and displays the results on the

screen. When you add a breakpoint to the Add function, notice how the new interactive debugging capabilities

of ASP.NET behave:

Start Microsoft Visual Studio .NET.Create a new Visual Basic ASP.NET Web Application project.

Name it ASPDebuggingExample.In WebForm1.aspx, switch to HTML view.Type or paste the following code between the opening and

closing FORM tags.

Note If you paste the code, paste it as HTML code. To do this, click

Paste as HTML on the Edit menu.

When you run the code, it prompts you to type two numbers and displays a

command button. When you click the command button, the code adds the two

numbers and displays the result on your screen.

<TABLE cellSpacing="1" cellPadding="1">









<TR><TD>




<asp:Label runat="server">First Number:</asp:Label>




</TD>




<TD>




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




</TD></TR>




<TR><TD>




<asp:Label runat="server">Second Number:</asp:Label>




</TD>




<TD>




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




</TD></TR>




<TR><TD>




<asp:Label runat="server">Sum:</asp:Label>




</TD>




<TD>




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




</TD></TR>




<TR><TD>




<asp:Button runat="server" Text="Add Numbers"></asp:Button>




</TD>




<TD>




</TD></TR>




</TABLE>




					

Click the Design button in the lower-left

corner of the Code window to switch to Design view.Double-click Add Numbers to view the code

and write an event handler for the command button's Click event.Add the following code to the event handler.

Dim intTotal as integer




Dim intFirstNumber as integer




Dim intSecondNumber as integer




			




' Get the values from the input boxes.




intFirstNumber = CInt(txtFirstNumber.Text)




intSecondNumber = CInt(txtSecondNumber.Text)




						




' Get the total and display it.




intTotal = intFirstNumber + intSecondNumber




txtSum.Text = CStr(intTotal)




					

Select the following line of code in the Button1_Click routine.

intTotal = intFirstNumber + intSecondNumber




						

Press F9 to set a breakpoint on this line.

A breakpoint

indicator appears on the line of code.Save the file. Build and then run the application. To do this, click

Start on the Debug menu.

WebForm1

appears on the screen. The input controls and the submit button also appear on

the form.Type a number in each of the first two input controls, and

then click Add Number.

The Visual Studio .NET

Integrated Development Environment (IDE) comes into focus and the code halts

when the breakpoint is reached. You can use the Locals window to examine the

contents of the variables and make any changes you want. You can add one or

more watches to trace the values of the variables in the routine. Or, you can

continue running the application.On the Debug menu, click

Continue to continue running the application.

WebForm1 appears on the screen and the result appears in the third input

box.Close the Web browser and return to the Visual Studio .NET

IDE.On the Debug menu, click Clear All

Breakpoints to remove all breakpoints from the application.

Verify that it works

When you click Add Number, the Visual Studio

.NET IDE comes into focus and the code stops running at the point where the

breakpoint is specified.

Add page-level tracing to the ASP.NET application

The following procedure sets up the Web application to allow the

tracing output to be displayed. It adds the page level Trace directive to the page to indicate that page-level tracing is

being used. The tracing code throughout the page tracks execution and the

variable contents:

In WebForm1.aspx, switch to HTML view. Add the following

attribute-value pair to the page directive at the top of the Code window.

Trace=True




					

Right-click WebForm1.aspx, and then click

View Code.In the Button1_Click routine, use trace statements to display the contents of

variables at several different points in the routine.

For example,

replace the existing routine with the following.

Trace.Write("Button1_Click", "Entering the Add routine")




			




Dim intTotal as integer




Dim intFirstNumber as integer




Dim intSecondNumber as integer




			




' Get values from the input boxes.




intFirstNumber = CInt(txtFirstNumber.Text)




intSecondNumber = CInt(txtSecondNumber.Text)




Trace.Write("Button1_Click", "Amount to add:" & _




CStr(intFirstNumber) & " and " & CStr(intSecondNumber))




			




' Get the total and display it.




intTotal = intFirstNumber + intSecondNumber




Trace.Write("Button1_Click", "Total:" & CStr(intTotal))




txtSum.Text = CStr(intTotal)	




			




Trace.Write("Button1_Click", "Leaving the Add routine")




					

Click Save.On the Debug menu, click

Start to build and run the application.

WebForm1

appears on the screen. Notice the tracing information for the application, such

as request information, tracing information, the hierarchical listing of

controls on the page, and any persistent items in the Application or Session

states.Type numbers into the first two input controls, and then

click Add Number.

The result appears in the third

input box. And, the custom trace messages from the Button1_Click routine appear in the Trace Information

section.

Verify that it works

The first time the form loads, general tracing information for the

page is displayed. If you click the Add Number button, the

custom trace messages from the Button1_Click routine appear in the Trace Information section.

Putting it all together

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">




<html>




	<head>




		<title>WebForm1</title>




		<meta name="GENERATOR" content="Microsoft Visual Studio.NET 7.0">




		<meta name="CODE_LANGUAGE" content="Visual Basic 7.0">




		<meta name="vs_defaultClientScript" content="JavaScript">




		<meta name="vs_targetSchema" content="http://http://www.zjjv.com///intellisense/ie5">




	</head>




	<Script language="vb" runat="server" id="script1">




		Sub Button1_Click(Sender as object, e as EventArgs)




			Trace.Write("Button1_Click", "Entering the Add routine")




			




			Dim intTotal as integer




			Dim intFirstNumber as integer




			Dim intSecondNumber as integer




			




			' Get the values from the input boxes.




			intFirstNumber = CInt(txtFirstNumber.value)




			intSecondNumber = CInt(txtSecondNumber.value)




			Trace.Write("Button_Click", "Amount to add:" & CStr(intFirstNumber) & " and " & CStr(intSecondNumber))




			




			' Get the total and display it.




			intTotal = intFirstNumber + intSecondNumber




			Trace.Write("Button1_Click", "Total:" & CStr(intTotal))




			txtTotal.value = CStr(intTotal)	




			




			Trace.Write("Button1_Click", "Leaving the Add routine")




		End Sub




	</Script>




	<body MS_POSITIONING="GridLayout">




		<form id="Form1" method="post" runat="server">




			<asp:Label id="lblFirstNumber" runat=server Width=125>




				First Number:




			</asp:Label> 




			<input id=txtFirstNumber type=text size=5 maxlength=3 




				runat=server NAME="txtFirstNumber"/>




			<br>




			<asp:Label id="lblSecondNumber" runat=server Width=125>




				Second Number:




			</asp:Label> 




			<input id=txtSecondNumber type=text size=5 maxlength=3 




				runat=server NAME="txtSecondNumber"/>




			<br>




			<asp:Label id="lblTotal" runat=server Width=125>




				Total:




			</asp:Label> 




			<input id="txtTotal" type=text size=5 maxlength=5 




				runat=server NAME="txtTotal" readonly/>




			<br><br>




			<input type=submit id=Button1 value="Add Numbers" onserverclick="Button1_Click" 




				runat=server NAME="Button1"/>




		</form>




	</body>




</html>




		"?><%@ Page Language="vb" Trace=true%>




<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">




<HTML>




	<HEAD>




		<title>WebForm1</title>




		<meta content="Microsoft Visual Studio.NET 7.0">




		<meta content="Visual Basic 7.0">




		<meta content="JavaScript">




		<meta content="http://http://www.zjjv.com///intellisense/ie5">




		<Script language="vb" runat="server">




		Sub Button1_Click(Sender as object, e as EventArgs)




		




            Trace.Write("Button1_Click", "Entering the Add routine")			




            Dim intTotal as integer




            Dim intFirstNumber as integer




            Dim intSecondNumber as integer




            			




            ' Get values from the input boxes.




            intFirstNumber = CInt(txtFirstNumber.Text)




            intSecondNumber = CInt(txtSecondNumber.Text)




            Trace.Write("Button1_Click", "Amount to add:" & _




            CStr(intFirstNumber) & " and " & CStr(intSecondNumber))




            			




            ' Get the total and display it.




            intTotal = intFirstNumber + intSecondNumber




            Trace.Write("Button1_Click", "Total:" & CStr(intTotal))




            txtSum.Text = CStr(intTotal)	




            			




            Trace.Write("Button1_Click", "Leaving the Add routine")









		End Sub




		</Script>




	</HEAD>




	<body MS_POSITIONING="GridLayout">




		<form method="post" runat="server">




			<TABLE cellSpacing="1" cellPadding="1">




				<TR>




					<TD><asp:Label runat="server">First Number:</asp:Label>




					</TD>




					<TD>




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




					</TD>




				</TR>




				<TR>




					<TD>




						<asp:Label runat="server">Second Number:</asp:Label>




					</TD>




					<TD>




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




					</TD>




				</TR>




				<TR>




					<TD>




						<asp:Label runat="server">Sum:</asp:Label>




					</TD>




					<TD>




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




					</TD>




				</TR>




				<TR>




					<TD>




						<asp:Button runat="server" Text="Add Numbers"></asp:Button>




					</TD>




					<TD>




					</TD>




				</TR>




			</TABLE>




		</form>




	</body>




</HTML>

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For more information, visit the following Microsoft

Developer Network (MSDN) Web sites:

http://http://www.zjjv.com///en-us/library/aa309369(VS.71).aspx

(http://http://www.zjjv.com///en-us/library/aa309369(VS.71).aspx)

http://http://www.zjjv.com///en-us/library/ms972204.aspx

(http://http://www.zjjv.com///en-us/library/ms972204.aspx)

For more information,

click the following article number to view the article in the Microsoft

Knowledge Base:

306172

(http://http://www.zjjv.com///kb/306172/

)

Common errors when you debug ASP.NET applications in Visual Studio .NET

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Article ID: 316726 - Last Review: June 19, 2012 - Revision: 6.0

APPLIES TO

Microsoft ASP.NET 1.1Microsoft ASP.NET 1.0

Keywords:

kbdebug kbhowtomaster kbide kbwebforms KB316726

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