how to convert a msvc exe project to a dll project? - visual-c++

Question

in the exe project:
int WINAPI WinMain( __in HINSTANCE hInstance, __in_opt HINSTANCE hPrevInstance, __in_opt LPSTR lpCmdLine, __in int nShowCmd )
{
g_hMainWnd=CreateDialog(hInstance,MAKEINTRESOURCE(IDD_DIALOG1),NULL,(DLGPROC)DialogProc);
RECT rcWnd;
GetWindowRect(g_hMainWnd,&rcWnd);
int X=(GetSystemMetrics(SM_CXSCREEN)-rcWnd.right+rcWnd.left)>>1,
Y=(GetSystemMetrics(SM_CYSCREEN)-rcWnd.bottom+rcWnd.top)>>1;
MoveWindow(g_hMainWnd,X,Y,rcWnd.right-rcWnd.left,rcWnd.bottom-rcWnd.top,FALSE);
ShowWindow(g_hMainWnd,SW_SHOW);
BOOL bRet;
MSG msg;
while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
{
if (bRet == -1)
{
MessageBox(NULL,_T("GetMessage error with -1 returned！"),_T("error"),MB_ICONHAND);
break;
}
else if (!IsWindow(g_hMainWnd) || !IsDialogMessage(g_hMainWnd, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return 0;
}
I changed the project setting to output a dll firstly.
Then I changed the WinMain to:
BOOL APIENTRY DllMain( __in HINSTANCE hInstance, __in_opt HINSTANCE hPrevInstance, __in_opt LPSTR lpCmdLine, __in int nShowCmd )
{
g_hMainWnd=CreateDialog(hInstance,MAKEINTRESOURCE(IDD_DIALOG1),NULL,(DLGPROC)DialogProc);
HWND hMainWnd;
//DialogProc involves the critical initialization of the data required for the export function used later
return 0;
}
So, if it is a foolish idea, or have I missed something?
Thank you all!

Answer 1

BOOL WINAPI DllMain(
HINSTANCE hinstDLL, // handle to DLL module
DWORD fdwReason, // reason for calling function
LPVOID lpReserved ) // reserved
{
// Perform actions based on the reason for calling.
switch( fdwReason )
{
case DLL_PROCESS_ATTACH:
// Initialize once for each new process.
// Return FALSE to fail DLL load.
break;
case DLL_THREAD_ATTACH:
// Do thread-specific initialization.
break;
case DLL_THREAD_DETACH:
// Do thread-specific cleanup.
break;
case DLL_PROCESS_DETACH:
// Perform any necessary cleanup.
break;
}
return TRUE; // Successful DLL_PROCESS_ATTACH.
}
For more informations: Dll entry point

Answer 2

The definition of DllMain is to be used by the operating system, and on a few occasions you must enter their codes. To execute the code that implements your EXE, you must create a public routine that receives the required parameters.
Use Visual Studio do create one library project to export some data and functions.
New Project-> Select Viasual c++ -> Select Win32 -> Win32 Project -> Name your project -> Next -> Select DLL -> Select Export symbols -> finish
The final project will contain a variable being exported and a public routine. Use as a template in your code.