SAMPLE: SFOLDER.EXE Gets the Path of a Special Folder (191198)

MORE INFORMATION

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When you run the self-extracting executable file, the following files are expanded into the Special Folders Path Sample Project directory:

• Form1.frm (14K) - The main form of the project.
• ITMalloc.tlb (3K) - The type library required to expose the Free method of the IMalloc operating system object. See the next section for more details.
• Project1.vbp (2K) - The project file.
• Project1.vbw (1K) - The workspace file.
• Readme.txt - You are currently reading this file.

How to Run the Sample

After expanding all the files, open the project file in the Visual Basic Integrated Development Environment (IDE). You need to make a reference to the ITMalloc.tlb type library and add the Microsoft Windows Common Controls 5.0 ActiveX component to the project.

1. Load the sample project into Visual Basic.
2. Press the F5 key or click Start from the Run menu to start the project. The ListView controls display a list of all special folders, their constant names and values, and the operating systems or browsers that use these folders.
3. Click a Special folder name to display the directory path. If the constant does refers to a virtual folder, such as Control Panel Programs-CSIDL_CONTROLS, text indicating a function failure appears in the text box.

How the Sample Works

Each special folder has a unique identification number that can only be accessed by a pointer to this number. This pointer is called a PIDL. Some of these folders map to a directory in your computer while others, such as CSIDL_DRIVES that is equivalent to the My Computer icon, do not have a directory. The list of special folders are shown in the code section of the sample project.

To get the a pointer to the PIDL of any special folder, use the SHGetSpecialFolderLocation function. This function fills the SHELLEXECUTEINFO user defined type with information about the special folder.

However, when you call the SHGetSpecialFolderLocation function, the calling application is responsible for freeing this pointer. You can free the pointer by using the Free method of the IMalloc operating system object through the SHGetMalloc function. Visual Basic can only access the Free method if the method is exposed through a type library. The ITMalloc.tlb type library to expose the Free method is included with the self-extracting file.

Once you have the PIDL of a special folder, you can get the directory path of this folder through the SHGetPathFromIDList function. This function fills a string buffer with the directory path of a special folder if the folder exists on the system. The function fails if you pass a special folder without a directory, such as My Computer.

   Platform SDK documentation on the following topics:

      Files and I/O
      SHGetSpecialFolderLocation
      SHGetPathFromIDList
      SHGetMalloc
      SHGetMalloc