VS2010 Appcode Folder Issues

It cannot be added in a Web application by right-clicking the project-〉 "Add"-〉 "Add ASP." Because App_Code does not exist in the Web application.
However, you can create it manually and add a folder named App_Code. The appearance of the App_Code created in this way and created in the Web site is the same.
Don't be happy first, it's not that simple.
When you create a class in App_Code, you will find no smart hints. When a page is referenced in the background, it is wrong to say that it does not exist.
The solution is to select your class file, in the properties "advanced" in the "Build Action" default "content" to be compiled instead.
That's all you have to do.

You can also add "App_LocalResources" to your Web application project, and it is also possible to add classes under this folder, so you do not need to add the App_Code folder.
You can also create a folder, or simply add a class without a folder, as long as you modify the class advanced properties of the "Build Action" to "compile" to

Transfer from http://blog.csdn.net/zorsbutape/article/details/6327156

VS2010 Appcode Folder Issues