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PO"Unresolved external _WinMain@16" if I move WndProc to another cpp file
 

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  1. PO"Unresolved external _WinMain@16" if I move WndProc to another cpp file
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    <p>For a Windows application I'm trying to get <code>CreateWindow()</code> and <code>WndProc()</code> (or my versions of them) to be part of a singleton class that is created at the beginning of <code>_tWinMain()</code> but since trying to shift the functions to <code>GameHandler.h</code> and <code>GameHandler.cpp</code> I keep getting "unresolved external symbol _WinMain@16". They were originally global functions in <code>main.cpp</code> and everything was compiling fine then I decided to move them to GameHandler and ever since all I get is the unresolved external, even if I try to move them back to <code>main.cpp</code>.</p> <p>I'm doing this in VS2010, the project was created as a Windows Application and there's no specific entry point set in properties (I double checked as every solution I've found so far says that it's because it's a console app - this isn't). </p> <p>The code I currently have is shown below. The actual project has a couple of thousand lines of other code that I've left out as I don't think it's relevant (but will happily proved wrong. While the actual window creation code is related, I don't think the code itself is the problem (apart from what I left in), it's the location of GameWindowProc() &amp;/or CreateGameWindow() or how they're called. The actual window creation code is taken from <a href="http://nehe.gamedev.net/tutorial/creating_an_opengl_window_%28win32%29/13001/" rel="nofollow">NeHe's tutorial</a>. Trying to compile the following code only gives the aforementioned unresolved external.</p> <p>main.cpp:</p> <pre><code>#include &lt;Windows.h&gt; #include "GameManager.h" #ifndef USEGMGR bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag); LRESULT CALLBACK GameWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam); #endif int APIENTRY _tWinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPTSTR lpCmdLine, int nCmdShow) { GameManager::Startup(); GameManager* GMgr = GameManager::GetInstance(); GMgr-&gt;SetProgramState(GAME_MODE); while(GMgr-&gt;GetProgramState() != GAME_MODE) // Normally this would be if (State != GAME_QUIT) { /* do game related stuff */ } GameManager::Shutdown(); return 0; } #ifndef USEGMGR bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag) { // Fairly complex but flexible creation code, taken from NeHe's tutorials. Of relevant interest is: WNDCLASS wc; // Windows Class Structure wc.lpfnWndProc = (WNDPROC) GameWindowProc; // WndProc Handles Messages if (!RegisterClass(&amp;wc)) // Attempt To Register The Window Class { MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION); return false; } return true; } LRESULT CALLBACK GameWindowProc(HWND hWnd, // Handle For This Window UINT uMsg, // Message For This Window WPARAM wParam, // Additional Message Information LPARAM lParam) // Additional Message Information { // various custom message handling, if not processed: return DefWindowProc(hWnd,uMsg,wParam,lParam); } #endif </code></pre> <p>in GameManager.h:</p> <pre><code>#ifndef GAMEMANAGER_H #define GAMEMANAGER_H #define USEGMGR // makes CreateGameWindow() and GameWindowProc() methods in GameManager instead of global #include &lt;Windows.h&gt; enum ProgramState { GAME_MODE, GAME_QUIT, }; class GameManager { public: static void Startup(); static void Shutdown(); static GameManager* GetInstance(); void Update(); // code not shown, check quit key etc #ifdef USEGMGR const bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag); static LRESULT CALLBACK GameWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam); #endif void KillGameWindow(void); const int GetProgramState() const; void SetProgramState(const int&amp; newMode); private: GameManager(); ~GameManager(); GameManager(const GameManager&amp;); GameManager&amp; operator=(const GameManager&amp;); HINSTANCE m_hInstance; HWND m_hWnd; HDC m_hDC; static GameManager* s_instance; int m_programState; // uses ProgramState enum }; #endif </code></pre> <p>in GameManager.cpp:</p> <pre><code>#include "GameManager.h" #include &lt;Windows.h&gt; #include &lt;assert.h&gt; #ifndef USEGMGR extern bool CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag); #endif GameManager* GameManager::s_instance = NULL; GameManager::GameManager(){} GameManager::~GameManager(){} void GameManager::Startup() { assert(s_instance == NULL); s_instance = new GameManager; #ifdef USEGMGR if (! (s_instance-&gt;CreateGameWindow("Game Window", 800, 600, 32, true )) ) #else if (! (CreateGameWindow("Game Window", 800, 600, 32, true )) ) #endif assert("CreateGameWindow failed! Need an error here"); // Quit If Window Was Not Created - clean this up later } void GameManager::Shutdown() { assert(s_instance != NULL); delete s_instance; s_instance = NULL; } GameManager* GameManager::GetInstance(){return s_instance;} void GameManager::Update(){/* msg handling, watch for quit key, etc */} const int GameManager::GetProgramState() const{return s_instance-&gt;m_programState;} void GameManager::SetProgramState(const int&amp; newState){s_instance-&gt;m_programState = newState;} #ifdef USEGMGR const bool GameManager::CreateGameWindow(char* title, int width, int height, int bits, bool fullScreenFlag) { // Fairly complex but flexible creation code, taken from NeHe's tutorials. Of relevant interest is: WNDCLASS wc; // Windows Class Structure wc.lpfnWndProc = (WNDPROC) GameManager::GameWindowProc; // WndProc Handles Messages if (!RegisterClass(&amp;wc)) // Attempt To Register The Window Class { MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION); return false; } return true; } LRESULT CALLBACK GameManager::GameWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) { // various custom message handling, if not processed: return DefWindowProc(hWnd,uMsg,wParam,lParam); } #endif </code></pre> <p>As you can see, I've set up some preprocessor conditionals to switch between the troublesome functions being in <code>main.cpp</code> or as part of GameManager. Comment out <code>#define USEGMGR</code> at the beginning of <code>GameManager.h</code> to have them as global funcs in <code>main.cpp</code>.</p> <p>Can someone please tell me what I'm doing wrong?</p> <p><em>Edit:</em> removed comment about not being able to quit if you get it to run.</p>
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