2d - How to exit a "game" in Qt when health is 0 -

i'm quite new qt, got start experimenting making 2d games. i've got extremely rough , simple game started, have issue. whenever health gets 0, game doesn't end. want know how end game , put exit command before making "game over" screen. code below, , can grasp, assume qapplication::quit() goes in game.cpp file. doing taking health integer health.cpp , health.h , putting in game.cpp. appreciated. here code feel answers lie in, if more info needed, ask.

game.h

#ifndef game_h #define game_h  #include <qgraphicsview> #include <qwidget> #include <qgraphicsscene> #include "player.h" #include "score.h" #include "health.h" #include "level.h" #include "main.h"  class game: public qgraphicsview{ public:     game(qwidget * parent=0);      qgraphicsscene * scene;     player * player;     score * score;     health * health;     level * level;     main * close;     int end(); };  #endif // game_h 

game.cpp

#include "game.h"  #include <qtimer> #include <qgraphicstextitem> #include <qfont> #include "enemy.h" #include <qmediaplayer> #include <qbrush> #include <qimage> #include <qapplication>  game::game(qwidget *parent){     // create scene     scene = new qgraphicsscene();     scene->setscenerect(0,0,800,600); // make scene 800x600        instead of infinity infinity (default)     setbackgroundbrush(qbrush(qimage(":/images/bg.png")));      // make newly created scene scene visualize (since game qgraphicsview widget,     // can used visualize scenes)     setscene(scene);     sethorizontalscrollbarpolicy(qt::scrollbaralwaysoff);     setverticalscrollbarpolicy(qt::scrollbaralwaysoff);     setfixedsize(800,600);      // create player     player = new player();     player->setpos(400,500); // todo generalize in     middle bottom of screen     // make player focusable , set current focus     player->setflag(qgraphicsitem::itemisfocusable);     player->setfocus();     // add player scene     scene->additem(player);      // create score/health     score = new score();     scene->additem(score);     health = new health();     health->setpos(health->x(),health->y()+25);     scene->additem(health);     level = new level();     scene->additem(level);bull     level->setpos(level->x(),level->y()+50);      // spawn enemies     qtimer * timer = new qtimer();     qobject::connect(timer,signal(timeout()),player,slot(spawn()));     timer->start(2000);      // play background music     qmediaplayer * music = new qmediaplayer();     music->setmedia(qurl("qrc:/sounds/bgsound.mp3"));     music->play();      show(); }  int game::end(){     if (health == 0){         qapplication::quit();     }     return 0; } 

health.h

#ifndef health_h #define health_h  #include <qgraphicstextitem>  class health: public qgraphicstextitem{ public:     health(qgraphicsitem * parent=0);     void decrease();     int gethealth(); private:     int health; };  #endif // health_h 

health.cpp

#include "health.h" #include <qfont> #include <qapplication>  health::health(qgraphicsitem *parent): qgraphicstextitem(parent){     // initialize score 0     health = 3;      // draw text     setplaintext(qstring("health: ") + qstring::number(health)); //   health: 3     setdefaulttextcolor(qt::red);     setfont(qfont("times",16)); }  void health::decrease(){     health--;     setplaintext(qstring("health: ") + qstring::number(health)); //     health: 2 }  int health::gethealth(){     return health; } 

main.cpp

#include <qapplication> #include "game.h" #include "main.h"  game * game;  int main(int argc, char *argv[]){     qapplication a(argc, argv);      game = new game();     game->show();      return a.exec(); } 

your end() function never called.

the best way achieve want use qt's signal/slot mechanism. amkes easy connect event (signal) action (slot):

• add q_object macro health , game classes , make sure compilation environment moc's 2 header files
• declare in health signal named dead()
• emit signal health::decrease()
• make game::end() slot , void
• connect health::dead() game::end()

then, game::end() called health reaches zero.

class health: public qgraphicstextitem  {     q_object public:     health(qgraphicsitem * parent=0);     void decrease();     int gethealth(); signals:     void dead(); private:     int health; };  ...  class game: public qgraphicsview{     q_object public:     ...  public slots:     void end(); };  ...  void health::decrease(){     health--;     setplaintext(qstring("health: ") + qstring::number(health));     if ( health == 0 )         emit dead(); }  ...  game::game(qwidget *parent){      ...      connect( health, signal(dead()), this, slot(end()) );  }  ...  void game::end(){     // no need test health anymore, signal emited when health 0     // stuff before exiting     qapplication::quit(); } 

if end() calls qapplication::quit(), can remove , diectly connect signal qapplication::quit(), that:

connect( health, signal(dead()), qapp, slot(quit()) ); 

also note testing health == 0 in game::end(), health pointer, and, looking @ code, never 0 (you maybe meant write if ( health->gethealth() == 0 ).