Simple Dll

myDll.c

#include <Windows.h>

#pragma comment(lib, "User32.lib") 

 /*
  * Compile with cl:
  * cl /nologo /LD myDll.c /link /out:myDll.dll
  *
  * Test:
  * rundll32 myDll.dll,#1
  *
  */
 
__declspec(dllexport) BOOL APIENTRY DllMain(HMODULE hModule, DWORD reason, LPVOID lpReserved)
{
	switch(reason)
	{
		case DLL_PROCESS_ATTACH:
		case DLL_THREAD_ATTACH:
			MessageBox(NULL, "DLL loaded",  "DLL Main", MB_OK);
			ExitProcess(1);
			break;
		case DLL_THREAD_DETACH:
		case DLL_PROCESS_DETACH:
			break;
	}
	
	return 0;
}