Uninstalling Your Application

The user may need to remove your application to recover disk space or to move the application to another location. To facilitate this, provide an uninstall program with your application that removes its files and settings. Remember to remove registry entries and shortcuts your application may have placed in the Start menu hierarchy. However, be careful when removing your application's directory structure not to delete any user files (unless you confirm their removal with the user).

Your uninstall program should follow the conventions detailed in this guide and in the following guidelines:

• Display a window that provides the user with information about the progress of the uninstall process. You can also provide an option to allow the program to uninstall "silently" — that is, without displaying any information so that it can be used in batch files.
• Display clear and helpful messages for any errors your uninstall program encounters during the uninstall process.
• When uninstalling an application, decrement the usage count in the registry for any shared component — for example, a dynamic-link library. If the result is zero, give the user the option to delete the shared component with the warning that other applications may use this file and will not work if it is missing.

Registering your uninstall program will display your application in the list of the Uninstall page of the Add/Remove Program utility included with Windows. To register your uninstall program, add the entries for your application to the Uninstall subkey.

HKEY_LOCAL_MACHINE
Software
Microsoft
Windows
CurrentVersion
Uninstall
ApplicationName DisplayName = Application Name
UninstallString = path [ switches ]

Both the DisplayName and UninstallString values must be supplied and be complete for your uninstall program to appear in the Add/Remove Program utility. The path you supply to UninstallString must be the complete command line used to carry out your uninstall program. The command line you supply should carry out the uninstall program directly rather than from a batch file or subprocess.