Determine the current HINSTANCE?

Question

The HINSTANCE of a win32 application is passed to WinMain, but is there any other way of determining the current HINSTANCE (in case you couldn't tell, I'm very new to win32 programming!)? I need to create a window inside of a library and (since the library is cross platform), I'd prefer not to have to pass it in.

Photographer

Worth mentioning: you don't actually need an instance handle to create a window. Just make hInstance = NULL when registering the class and pass NULL to CreateWindow() and you're good to go. – Jarret

@Jarret That's not correct. Specifically in the case of a library (when compiled into DLL) the HINSTANCE becomes a crucial part in identifying the window class. Details here: What is the HINSTANCE passed to CreateWindow and RegisterClass used for?. – Bentham

Answer 1

If memory serves, GetModuleHandle(NULL); returns the instance handle.

Highoctane

Not totally correct: It reutrns the HINSTANCE of the exe. If the code executes in a DLL, this may lead to wrong behaviours – Lillie

@Serge: from what he's saying, the HINSTANCE of the executable is exactly what he wants. – Highoctane

+1: By passing in a module name, that function can be used to get the HINSTANCE of DLLs as well. Note that HINSTANCE and HMODULE are essentially equivalent in modern versions of Windows. – Manners

Adrian, how would the code in the library know in which module (exe/dll) it sits? – Lillie

Answer 2

__ImageBase is your friend, especially in the case of libraries.

Note that the linked blog post (by R. Chen, although not the same post as the one linked by Brian Bondy) is worth reading (including the comments!)

Lillie

Ignoring the cumbersome GetModuleHandleEx with GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS, this is really the only reliable way to find the module handle, and it should be the accepted answer. – Bentham

Answer 3

If you are using MFC, you can use AfxGetInstanceHandle.

If you are not using MFC you can use: GetWindowLong(hWnd, GWL_HINSTANCE)

Kumkumagai

That assumes I already have a window (and thus, and hwnd)... I'm trying to push the job of window creation out to my library... – Photographer

Please review this link, I think you may run into the problem Raymond is talking about: blogs.msdn.com/oldnewthing/archive/2005/04/18/409205.aspx – Kumkumagai

Both AfxGetInstanceHandle and GetWindowLong returns HINSTANCE of the application, but you can call AfxGetInstanceHandle without creating a window. – Handful

You could set a global variable if you really wanted to as well and extern it in. – Kumkumagai

The GetWindowLong() version assumes a 32 bit platform build. But on Win64, you run into trouble. – Headwaters

Answer 4

The function AfxGetStaticModuleState() does the trick. If you call it within a dll, the functions returns the handle to the dll, if the call within a exe it returns the handle to the executable.

DWORD size;
TCHAR fileName [MAX_PATH];
HMODULE hModule = AfxGetStaticModuleState()->m_hCurrentInstanceHandle;
::GetModuleFileName (hModule, fileName, size);

Fidelfidela

The question is tagged winapi. There is no AfxGetStaticModuleState in the Windows API. – Bentham