Thread: DLL problem

Here is a very basic dll demo that works. See if you can see what I did and then compare that to what you did (heres a hint: if something's different you are probably wrong).

Here is the dll file code:

Code:

#ifdef __cplusplus
#define EXPORT extern "C" __declspec(dllexport)
#else
#define EXPORT __declspec(dllexport)
#endif

#include <windows.h>

EXPORT void doBeep(void);

int WINAPI DllMain(HINSTANCE hInstance, DWORD fdwReason, PVOID pvReserved ) {

	return true;
}

EXPORT void doBeep(void) {

	for(int i = 0; i<5; i++)
		MessageBeep(0);

}

Here is the def file code

Code:

LIBRARY	DLLdemo
EXPORTS
	doBeep

And finnally here is the code for the test app:

Code:

#include <windows.h>

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

//define my pointer type to the function---------------------------------------
typedef int(*myProc)(void);
myProc proc = NULL;
//-----------------------------------------------------------------------------

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) {

	static TCHAR szAppName[] = TEXT("dllTest");
	HWND hwnd;
	MSG msg;
	WNDCLASS wc;
	
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wc.hCursor = LoadCursor(NULL, IDC_ARROW);
	wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	wc.hInstance = hInstance;
	wc.lpfnWndProc = WndProc;
	wc.lpszClassName = szAppName;
	wc.lpszMenuName = NULL;
	wc.style = CS_HREDRAW | CS_VREDRAW;

	if(!RegisterClass(&wc)){
		MessageBox(NULL, TEXT("Could not register class"), szAppName, MB_ICONERROR);
		return (0);
	}

	hwnd = CreateWindow(szAppName, TEXT("dllTEST"), WS_OVERLAPPEDWINDOW, 100, 100, 300, 300, NULL, NULL, hInstance, NULL);

	ShowWindow(hwnd, iCmdShow);
	UpdateWindow(hwnd);

	while(GetMessage(&msg, NULL, 0, 0)){
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam ;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {

	static HINSTANCE hInstLib; //handle to the library
	
	
	BOOL fFreeResult;

	switch(message) {
			
		case WM_CREATE:
			
			hInstLib = LoadLibrary("Dlldemo.dll"); //Load the dll
			proc = (myProc)GetProcAddress(hInstLib, TEXT("doBeep"));//Get address of function
			proc();//call function
			return(0);
		case WM_DESTROY:
			fFreeResult = FreeLibrary(hInstLib); //release library		
			PostQuitMessage(0);
			return(0);
	}
	return DefWindowProc(hwnd, message, wParam, lParam);
}

This should get you going in the right direction.