c++ - Window Class Registration Failed -
i writing beginnings of game win32 application. worked fine when registered class within main.cpp, i'm trying move game class make code easier me use.
since have moved code game class, window class registration fails. here code, please note functions empty because haven't got far yet.
getlasterror() returns 87.
main.cpp
#include "main.h" // entry point program, see game explanation of parameters int winapi winmain(hinstance hinstance, hinstance hprevinstance, lpstr lpcmdline, int ncmdshow) { game = std::unique_ptr<game>(new game(hinstance, hprevinstance, lpcmdline, ncmdshow)); game->init(); // main game loop while(game->isrunning()) { game->handlemessages(); game->update(0.0f); game->render(); } return exit_success; } game.cpp
#include "game.h" #include <windows.h> lpcwstr g_szclassname = l"life simulator window class"; game::game(hinstance _hinstance, // handle instance of application hinstance _hprevinstance, // handle previous instance of application lpstr _lpcmdline, // command line parameters int _ncmdshow) // controls how window show) { hinstance = _hinstance; hprevinstance = _hprevinstance; lpcmdline = _lpcmdline; ncmdshow = _ncmdshow; return; } game::~game(void) { } bool game::init() { // set paramaters window class wc.cbclsextra = 0; // number of bytes allocate after window class, not needed showing verbosity wc.cbsize = sizeof(wndclassex); // stores size of wndclassex structure, helping future proof application in case new fields added wc.cbwndextra = 0; // similar cbclsextra, refers window rather window class wc.hbrbackground = (hbrush) (color_window); // handle background brush, in case it's colour cast brush handle wc.hcursor = loadcursor(null, idc_arrow); // handle cursor, first paramater handle instance of application containing cursor (not needed in case), second resource identifier wc.hicon = loadicon(null, idi_application); // similar hcursor, application icon instead wc.hiconsm = loadicon(null, idi_application); // above, smaller version of icon wc.hinstance = hinstance; // handle instance of application contains window procedure wc.lpfnwndproc = game::wndproc; // pointer window procedure wc.lpszclassname = g_szclassname; // window class name (see global variables) wc.lpszmenuname = null; // specifies resource name of menu, isn't used in case wc.style = cs_hredraw | cs_vredraw; // style window class, in case means redraw if it's affected (i.e. resized or moved) vertically or horizontally // register window class if(!registerclassex(&wc)) { // code executed if window class fails register messagebox(null, // owner message box can specified here l"window class registation failed.", // message displayed l"fatal error", // title of message box mb_iconexclamation | mb_ok); // type of message box, in case has exclamation icon , ok button return exit_failure; // return exit_failure indicate program closed due runtime error } // create window hwnd = createwindowex(ws_ex_overlappedwindow, // extended window style g_szclassname, // class of window created (this window class created earlier) l"life simulator", // title of window ws_overlappedwindow, // window style cw_usedefault, // x position of window, here default values used cw_usedefault, // above, y position wndwidth, // width of window wndheight, // height of window null, // parent window, if has 1 null, // handle menu window hinstance, // handle instance of application null); // lpparam can passed on here if(hwnd == null) { // code executed if creating window failed messagebox(null, // owner message box can specified here l"window creation failed.", // message displayed l"fatal error", // title of message box mb_iconexclamation | mb_ok); // type of message box, in case has exclamation icon , ok button return exit_failure; // return exit_failure indicate program closed due runtime error } showwindow(hwnd, // handle window shown ncmdshow); // passed on winmain, controls how window should shown (i.e. minimised or maximised) updatewindow(hwnd); // forces window updated forcing wm_paint message past application queue } // window procedure game lresult callback game::wndproc(hwnd hwnd, // handle window uint msg, // message processed wparam wparam, // additional message information lparam lparam) // more additional message information { switch(msg) { case wm_close: // red x has been clicked destroywindow(hwnd); // sends wm_destroy window break; case wm_destroy: // part of program has requested window destroyed postquitmessage(0); // sends quit message window break; default: // unhandled messages return defwindowproc(hwnd, msg, wparam, lparam);// windows handle messages haven't been handled explicitly } return 0; } void game::handlemessages() { while(peekmessage(&msg, // container message null, // when multiple windows used, can specify 1 here 0, // used filter messages, not needed here 0, // above pm_remove)) // remove messages after they've been processed { translatemessage(&msg); // turns virtual key messages character messages dispatchmessage(&msg); // sends message on window procedure (i.e. wndproc) } return; } void game::update(float elapsedtime) { return; } void game::render() { return; } previously working main.cpp
#include <windows.h> // global variables lpcwstr g_szclassname = l"life simulator window class"; // l casts string wide string , called g_szclassname convention, making code easier read others static const int wndheight = 800; static const int wndwidth = 600; // window procedure program lresult callback wndproc(hwnd hwnd, // handle window uint msg, // message processed wparam wparam, // additional message information lparam lparam) // more additional message information { switch(msg) { case wm_close: // red x has been clicked destroywindow(hwnd); // sends wm_destroy window break; case wm_destroy: // part of program has requested window destroyed postquitmessage(0); // sends quit message window break; default: // unhandled messages return defwindowproc(hwnd, msg, wparam, lparam);// windows handle messages haven't been handled explicitly } } // entry point program int winapi winmain(hinstance hinstance, // handle instance of application hinstance hprevinstance, // handle previous instance of application lpstr lpcmdline, // command line parameters int ncmdshow) // controls how window show { // initialise variables hwnd hwnd; // handle window wndclassex wc; // window class container msg msg; // window message container // set paramaters window class wc.cbclsextra = 0; // number of bytes allocate after window class, not needed showing verbosity wc.cbsize = sizeof(wndclassex); // stores size of wndclassex structure, helping future proof application in case new fields added wc.cbwndextra = 0; // similar cbclsextra, refers window rather window class wc.hbrbackground = (hbrush) (color_window); // handle background brush, in case it's colour cast brush handle wc.hcursor = loadcursor(null, idc_arrow); // handle cursor, first paramater handle instance of application containing cursor (not needed in case), second resource identifier wc.hicon = loadicon(null, idi_application); // similar hcursor, application icon instead wc.hiconsm = loadicon(null, idi_application); // above, smaller version of icon wc.hinstance = hinstance; // handle instance of application contains window procedure wc.lpfnwndproc = wndproc; // pointer window procedure wc.lpszclassname = g_szclassname; // window class name (see global variables) wc.lpszmenuname = null; // specifies resource name of menu, isn't used in case wc.style = cs_hredraw | cs_vredraw; // style window class, in case means redraw if it's affected (i.e. resized or moved) vertically or horizontally // register window class if(!registerclassex(&wc)) { // code executed if window class fails register messagebox(null, // owner message box can specified here l"window class registation failed.", // message displayed l"fatal error", // title of message box mb_iconexclamation | mb_ok); // type of message box, in case has exclamation icon , ok button return exit_failure; // return exit_failure indicate program closed due runtime error } // create window hwnd = createwindowex(ws_ex_overlappedwindow, // extended window style g_szclassname, // class of window created (this window class created earlier) l"life simulator", // title of window ws_overlappedwindow, // window style cw_usedefault, // x position of window, here default values used cw_usedefault, // above, y position wndwidth, // width of window wndheight, // height of window null, // parent window, if has 1 null, // handle menu window hinstance, // handle instance of application null); // lpparam can passed on here if(hwnd == null) { // code executed if creating window failed messagebox(null, // owner message box can specified here l"window creation failed.", // message displayed l"fatal error", // title of message box mb_iconexclamation | mb_ok); // type of message box, in case has exclamation icon , ok button return exit_failure; // return exit_failure indicate program closed due runtime error } showwindow(hwnd, // handle window shown ncmdshow); // passed on winmain, controls how window should shown (i.e. minimised or maximised) updatewindow(hwnd); // forces window updated forcing wm_paint message past application queue // message loop while(true){ // program closes instantly otherwise while(peekmessage(&msg, // container message null, // when multiple windows used, can specify 1 here 0, // used filter messages, not needed here 0, // above pm_remove)) // remove messages after they've been processed { translatemessage(&msg); // turns virtual key messages character messages dispatchmessage(&msg); // sends message on window procedure (i.e. wndproc) } } return msg.wparam; // contains exit code last message, wm_quit } game.h
#pragma once #include <windows.h> class game { public: game(hinstance hinstance, // handle instance of application hinstance hprevinstance, // handle previous instance of application lpstr lpcmdline, // command line parameters int ncmdshow); // controls how window show ~game(void); bool init(); bool isrunning(){return isrunning;} // window procedure game static lresult callback wndproc(hwnd hwnd, // handle window uint msg, // message processed wparam wparam, // additional message information lparam lparam); // more additional message information void handlemessages(); // messages translated , dispatched here void update(float elapsedtime); // game logic void render(); // display results public: // changed public until can working bool isrunning; hinstance hinstance; hinstance hprevinstance; lpstr lpcmdline; int ncmdshow; lpcwstr g_szclassname; // l casts string wide string , called g_szclassname convention, making code easier read others static const int wndheight = 600; // window height static const int wndwidth = 800; // window width hwnd hwnd; // handle window wndclassex wc; // window class container msg msg; // window message container };
the problem have g_szclassname declared both member variable , global variable. member variable g_szclassname not initialized anywhere , can point anything.
there no reason have wc , msg declared member variables not need persist throughout lifetime of object. make them local variables instead.
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