Toggle Word Wrap button in .NET framework

Generating QR-Code in .NET framework Toggle Word Wrap button

Click the Toggle Word Wrap button on the Output pane (shown in Figure 20-4) to show the build results without the need to scroll horizontally

You can build a whole Web project to test for errors Right-click the project root and choose Build Web Site Visual Web Developer can exclude buggy or incomplete pages from the build process In Solution Explorer, right-click a page you want to exclude and choose Exclude From Project from the context menu VWD adds an exclude extension to the filename so that it won t appear as an ASPNET file To unexclude a file, right-click and choose Include In Project

Visual Web Developer has loads of sophisticated tools for monitoring, dissecting, and troubleshooting your code The hard part might be knowing which tool is best for the task In this section, you set breakpoints, step through code, examine the errors list, and use the various debugger windows

The best way to check if a page runs is to, er, run it Browse to the page that you created from Listing 20-1 right-click the file in Solution Explorer and choose View in Browser The result is depressingly underwhelming The drop-down list appears but nothing s in it This confirms a bug exists The debugger helps you find it

A breakpoint pauses the execution of a program so that you can analyze the logic When you execute a page in the debugger, Visual Web Developer compiles the code, launches the browser, and runs the code until it reaches a breakpoint In your buggy example, code within the handler for the Page Load event is supposed to fill the drop-down list The Load event is a good place to look for an error Follow these steps to set a breakpoint:

Large-scale, enterprise Web projects often use test-driven development where a developer writes testing code to prove that each subroutine works as expected The accumulated tests stay with the code for repeated runs to catch bugs that slip in during further development Geeks call errors that appear in previously working code regression errors or regressions Test-driven development is a valuable technique, although you may feel that writing tests is overkill on small projects where code quality isn t as critical as it would be in an online banking application

1 Open the sample ASPNET page in Source view 2 Locate the handler code for the Page Load event (it s near the top of the source code) 3 Click in the gray margin to the left of the code A red dot appears and the IDE highlights the corresponding line of code, as shown in Figure 20-5 That red dot marks the breakpoint

4 Choose Debug Start Debugging If you re debugging the project for the first time, a dialog box appears with an offer to enable debugging Click OK The IDE builds the page, launches the browser, and then returns to the source code at the location of the breakpoint 5 Choose Debug Step Into (or press F11) The arrow advances to the next line of code, which is an If statement, as shown in Figure 20-6

6 Watch the code carefully and advance the execution another step (F11) Yikes! The debugger jumped straight to the End If statement, bypassing the code that fills the drop-down list 7 End the debugging session by choosing Debug Stop Debugging You know the location of the problem (which is half the battle), but not why the code failed

While you step through code in the debugger, Visual Web Developer generates a huge amount of information about what s occurring Follow these steps to examine the values of objects and to discover why the code didn t execute: 1 On the sample ASPNET page, run the debugger (F5) to the breakpoint You set the breakpoint in the preceding section, Setting a breakpoint in the code 2 Step into the next statement (F11) that has the following line of code: If PageIsPostBack = True Then 3 Hover the mouse pointer over the IsPostback property As shown in Figure 20-7, the value of PageIsPostback pops up and it is False 4 Close the debugger (Debug Stop Debugging) The problem is clear: PageIsPostBack is False when a page runs for the first time (there hasn t been a chance for a postback to happen) However, the