INFO: Alternatives to Using GetProcAddress() With LoadLibrary()

ID: Q92862

The information in this article applies to:

Microsoft Win32 Application Programming Interface (API), used with:
- Microsoft Windows NT versions 3.1, 3.5, 3.51, 4.0
- Microsoft Windows 95
- Microsoft Windows 2000

SUMMARY

When loading a DLL with LoadLibrary(), an alternative to calling GetProcAddress() for each of your DLL entry points is to have the DLL initialization function initialize a global structure or array containing the addresses of these DLL entry points, then call a DLL function from your executable which will return the address of this structure or array to your executable. You can then call your DLL functions via the function pointers in this structure or array.

MORE INFORMATION

The best place to initialize this structure or array of function pointers would be in the DLL_PROCESS_ATTACH code of your DLL's main entry point. The structure or array containing these function pointers must be declared as either a global variable or as dynamically allocated memory (malloc(), GlobalAlloc(), etc.) in your DLL in order for the executable to be able to address this memory properly.

It is also possible, though not as clean, to export the global structure or array of function pointers so that your executable can use the structure or array by name directly in your executable. For additional information on how to declare and export global data in a Win32 DLL, click the article number below to view the article in the Microsoft Knowledge Base:

Q90530 Exporting Data From a DLL

Be careful not to call these DLL functions via the function pointers after the DLL is unloaded via FreeLibrary(). After FreeLibrary() is called, these function pointer addresses are invalid and calling them will result in an access violation.

This technique of returning pointers to DLL entry points is a supported technique and will work on all hardware platforms that Windows NT supports.

Additional query words: 3.10 3.50

Keywords : kbDLL kbKernBase kbNTOS310 kbNTOS350 kbNTOS351 kbNTOS400 kbWinOS2000 kbWinOS95 kbDSupport kbGrpKernBase
Version : winnt:3.1,3.5,3.51,4.0
Platform : winnt
Issue type : kbinfo