Advanced Testing and Debugging of an ASP.NET 2.0 Application
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In this article, you will learn how to create a website that runs under IIS for testing purposes. You will also learn how to create and test a file-system website with the ASP.NET Development Server. The third of three parts, this article is excerpted from chapter four of the book
Murach's ASP.NET 2.0 Web Programming with VB 2005, written by Joel Murach and Anne Boehm (Murach, 2006; ISBN: 1-890774-32-4).
How to use the Immediate window to work with values
The Immediate window, shown in figure 4-14, is useful for displaying the values of variables or properties that don’t appear in the Code Editor window. To display a value, you simply type a question mark followed by the name of the variable or property. The first line of code in this figure, for example, displays the Text property of the item selected from the Products drop-down list. You can see the result in the second line of this window.
The Immediate window is also useful for executing C# statements. For example, you can execute an assignment statement to change the value of a variable or property. After I displayed the Text property of the Quantity text box, for example, I assigned a value of 1 to this property. Similarly, you can execute a user-defined method. This can be useful for testing the result of a method with different arguments. If you execute a method that returns a value, you can also preface the method name with a question mark to display the value it returns.
When you enter commands in the Immediate window, they’re executed in the same context (or scope) as the application that’s running. That means that you can’t display the value of a variable that’s out of scope. If you try to do that, the debugger displays an error message.
The commands that you enter into the Immediate window remain there until you exit from Visual Studio or explicitly delete them using the Clear All command in the shortcut menu for the window. That way, you can use standard Windows techniques to edit and reuse the same commands from one execution of an application to another without having to reenter them.
To execute a command that you’ve already entered in the Immediate window, just use the Up and Down arrow keys to scroll through the commands. As you scroll, the commands are displayed at the bottom of the window. Then, you can change a command if necessary and press Enter to execute it.
The Immediate window
Figure 4-14. How to use the Immediate window to work with values
Description
- You can use the Immediate window to display and assign values from a program during execution. To display this window, click on the Immediate Window tab or use the Debug->Windows->Immediate command.
- To display a value in the Immediate window, enter a question mark followed by the expression whose value you want to display. Then, press the Enter key.
- To assign a different value to a variable, property, or object, enter an assignment statement in the Immediate window. Then, press the Enter key.
- To execute a user-defined method from the Immediate window, enter its name and any arguments it requires. Then, press the Enter key. If you want to display the value that’s returned by a method, precede the method call with a question mark.
- To reissue a command, use the Up and Down arrow keys to scroll through the commands until you find the one you want. Then, modify the command if necessary and press the Enter key to execute it.
- To remove all commands and output from the Immediate window, use the Clear All command in the shortcut menu for the window.
Next: How to use the Trace feature >>
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 This article is excerpted from chapter four of the book Murach's ASP.NET 2.0 Web Programming with VB 2005, written by Joel Murach and Anne Boehm (Murach, 2006; ISBN: 1-890774-32-4). Check it out today at your favorite bookstore. Buy this book now.
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