What are some of the possible causes of "entry point not found" runtime error?

Question

I am trying to compile a program that is created from Visual Studio 8, converted it to Visual Studio 9. After giving all the required .DLL, .lib, and #include directories, I successfully compiled the program. However, when I tried to launch it, it always give out an error:

The procedure entry point SwapBuffers could not be located in the dynamic link library OpenGL32.DLL.

I checked my directories. OpenGL32.DLL does exist! I even download OpenGL32.dll again in case, mine is an old version; nope, it doesn't work. I even tried putting OpenGL32.dll right beside the built .exe. Nope, it still gives out the same error.

Do you appear to know what are some of the possible causes here?

Answer 1

Looks like SwapBuffers functions simply isn't there. Do you get a warning on compile time about undefined references or such?

Try exploring the dll with a proper tool to view export tables and look for the function - se if it's there (google gave me this: DLL Export Viewer)

You could also try loading it dynamicly like this:

HMODULE lib = LoadLibraryA("OpenGL32.DLL");
FARPROC WINAPI proc = GetProcAddress(lib, "SwapBuffers");

if (!proc)
   printf("SwapBuffers() not found\n");

Be careful calling the function pointer proc directly without knowing the calling convention used in the dll (probably stdcall) or your stack might get malaligned.