Program crashes with 0xC0000005 error code

Hello everyone,

I have made small computer game using QT in CLion.
At beginning I show main menu with four rect items created as buttons, I connect it to some slots f.e start() - slot which start game, showHelp() - showing help informations, showScores() - top scores and the last one is quit connected to close() slot.

Let me explain how my code works - I running for first time application then all items in the main menu working. When I click the start button it bring me to start method and all code from this method working as I wish.
If the player health is equal 0 or lower program showing gameOverWindow() and in this window have two buttons. One is playAgain and this button restarting game, next one moving to main menu - this menu which are displayed at start of my program.

The problem that arises is when I click play again button it successful restart game, but sometimes it crashing my application at showGameOverWindow or after when I back to mainMenuWindow with those error information:

Quote:

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pure virtual method called terminate called without an active exception

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but not always, sometimes it's this exit code:

Quote:

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Process finished with exit code -1073741819 (0xC0000005)

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When it doesn't crash after that cases program will always crash after clicking any button in mainMenu without play game button.

Any help would be appreciated

Source code:

Code which checking health is under or equal 0

Code:

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//some useless code before
if (game->health->getHealth() <= 0){
                int score = game->score->getScore();
 
                game->scene->clear();
                game->ShowGameOverWindow(score);
}

---

ShowGameOverWindow

Code:

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void Game::ShowGameOverWindow(int score){
    setBackgroundBrush(QImage("../Sources/Pictures/gameover.png"));
    float height = window()->height();
    float width = window()->width();
 
    drawPanel(0,0,860,600,Qt::black,0.35);
    drawPanel(width/4+30,height/4,400,400,Qt::lightGray,0.75);
 
    backMenuButton = new Button(QString("../Sources/Pictures/Menu/ok-inactive.png"),
                            QString("../Sources/Pictures/Menu/ok-active.png"));
    int qxPos = width-320;
    int qyPos = height-110;
    backMenuButton->setPos(qxPos, qyPos);
    connect(backMenuButton, SIGNAL(clicked()), this, SLOT(displayMainMenu()));
    scene->addItem(backMenuButton);
 
    playAgainButton = new Button(QString("../Sources/Pictures/Menu/again-inactive.png"),
                            QString("../Sources/Pictures/Menu/again-active.png"));
    int pxPos = width/3-30;
    int pyPos = height-110;
    playAgainButton->setPos(pxPos, pyPos);
    playAgainButton->setSize(200,51);
    connect(playAgainButton,SIGNAL(clicked()), this, SLOT(start()));
    scene->addItem(playAgainButton);
}

---

start game slot

Code:

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void Game::start() {
    scene->clear();
 
    scene->setSceneRect(0,0,800,600);
    setFixedSize(800,600);
    setBackgroundBrush(QImage("../Sources/Pictures/gameBackground.png"));
 
    player = new Player();
    player->setFlag(QGraphicsItem::ItemIsFocusable);
    player->setFocus();
    player->resetPos();
    scene->addItem(player);
 
    score = new Score();
    score->resetScore();
    score->setPos(score->x()+600, score->y()+9);
    scene->addItem(score);
 
    health = new Health();
    health->resetHealth();
    health->setPos(health->x()+380, health->y()+9);
    scene->addItem(health);
 
    if(!mainTimer->isActive()) {
        connect(mainTimer, SIGNAL(timeout()), this, SLOT(mainLoop()));
        mainTimer->start(0);
    }
    counting(1000);
 
    auto * timerHurdle = new QTimer();
    QObject::connect(timerHurdle,SIGNAL(timeout()),player,SLOT(spawnHurdle()));
    timerHurdle->start(2000);
 
    auto * timerHeart = new QTimer();
    QObject::connect(timerHeart,SIGNAL(timeout()),player,SLOT(spawnHeart()));
    timerHeart->start(10000);
}

---

Display main menu

Code:

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void Game::displayMainMenu() {
    scene->clear();
 
    scene->setSceneRect(0,0,1030,768);
    setFixedSize(1030,768);
    setBackgroundBrush(QImage("../Sources/Pictures/Menu/background.png"));
 
    // buttons and properties
    playButton = new Button(QString("../Sources/Pictures/Menu/start-inactive.png"),
                            QString("../Sources/Pictures/Menu/start-active.png"));
    int bxPos = playButton->boundingRect().width()/8 + 3;
    int byPos = 380;
    playButton->setPos(bxPos, byPos);
    connect(playButton,SIGNAL(clicked()), this, SLOT(start()));
    scene->addItem(playButton);
 
    scoreButton = new Button(QString("../Sources/Pictures/Menu/scores-inactive.png"),
                             QString("../Sources/Pictures/Menu/scores-active.png"));
    int sxPos = scoreButton->boundingRect().width()/8 + 3;
    int syPos = 450;
    scoreButton->setPos(sxPos, syPos);
    connect(scoreButton,SIGNAL(clicked()), this, SLOT(showScores()));
    scene->addItem(scoreButton);
 
    helpButton = new Button(QString("../Sources/Pictures/Menu/help-inactive.png"),
                            QString("../Sources/Pictures/Menu/help-active.png"));
    int hxPos = helpButton->boundingRect().width()/8 + 3;
    int hyPos = 520;
    helpButton->setPos(hxPos, hyPos);
    connect(helpButton,SIGNAL(clicked()), this, SLOT(showHelp()));
    scene->addItem(helpButton);
 
 
    quitButton = new Button(QString("../Sources/Pictures/Menu/quit-inactive.png"),
                            QString("../Sources/Pictures/Menu/quit-active.png"));
    int qxPos = quitButton->boundingRect().width()/8 + 3;
    int qyPos = 610;
    quitButton->setPos(qxPos, qyPos);
    connect(quitButton,SIGNAL(clicked()), this, SLOT(close()));
    scene->addItem(quitButton);
 
    backButton = new Button(QString("../Sources/Pictures/Menu/back-inactive.png"),
                            QString("../Sources/Pictures/Menu/back-active.png"));
    int backxPos = scene->width()/2 - 40;
    int backyPos = 610;
    backButton->setPos(backxPos, backyPos);
    connect(backButton,SIGNAL(clicked()), this, SLOT(displayMainMenu()));
    scene->addItem(backButton);
 
    parchmentImage = new QLabel();
    QPixmap img("../Sources/Pictures/Menu/paper.png");
    parchmentImage->setPixmap(img);
 
 
    double x = img.width();
    double y = img.height();
    parchmentImage->setGeometry(300,250,x,y);
    scene->addWidget(parchmentImage);
 
    info = new TextInformation();
    info->setPosition(300,270);
    scene->addItem(info);
 
 
    if(backButton->isVisible()) { scene->removeItem(backButton); }
    if(info->isVisible())       { scene->removeItem(info); }
 
 
    info->setProperties(Qt::black,"arial",16,300,270);
    parchmentImage->setHidden(true);
 
 
    playButton->setEnabled(true);
    scoreButton->setEnabled(true);
    helpButton->setEnabled(true);
    quitButton->setEnabled(true);
 
}

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If the problem is too hard to imagine I can make short video to show you how I really looks or even paste more source code.

You are almost certainly attempting to access something through a pointer that is no longer valid. Start the program in your debugger and, when it crashes, obtain the stack backtrace. Reading the trace from the top, the first line of your code (i.e. outside the Qt library) is the place to start looking.

When are you calling the methods you have listed above? Every time you start a new game or show the "game over" window? If these functions are being called multiple times, then it seems to me that you have a serious logic problem: it looks like you are creating member variables multiple times instead of creating them once (in a constructor or some other "initialize" method that is called once) and re-using them. Every time you call new() to assign a member variable, the previous value assigned to that variable is lost. At best you have a memory leak, at worst you could be using a copy of a pointer that no longer points to the newly-created member variable.

You also haven't shown any code where you define and assign initial values to your member variables. An unassigned pointer variable can easily cause a crash if you try to use it before it is assigned (or after it is deleted).

As ChrisW67 says, create a debug version of you program and run it in the debugger until it crashes. The stack trace will show you where. Also when compiling your program do not ignore compiler warnings about unassigned variables or other potential problems.

Okey, I got it, thank you so much.
I run program in the debugger and bug was in mainLoop function. This function was called all the time when timer was connected into this slot method. I fixed it by disconnecting object from any signals, and this working.

Sorry, for my topic. I run the debugger earlier but I don't see any problem with this function where the debugger bring me.