CODEWITHSUNDEEP
c++exception
kovac
kovac

Reputation: 5389

Microsoft C++ exception runtime_error at memory location (Code 0x75A818A2)

I have the following class definition:

class DisplayManager
{
public:
    static DisplayManager *getInstance();
    DisplayManager(DisplayManager const&) = delete;
    void operator=(DisplayManager const&) = delete;
    ~DisplayManager();

    void addDisplay(ALLEGRO_DISPLAY &display);
private:
    DisplayManager();

    ALLEGRO_DISPLAY *mDisplay = nullptr;
};

The implementation of the class is:

DisplayManager *DisplayManager::getInstance()
{
    static DisplayManager instance;
    return &instance;
}

DisplayManager::~DisplayManager()
{}

void DisplayManager::addDisplay(ALLEGRO_DISPLAY &display)
{
    if(!mDisplay)
    {
        throw std::runtime_error("Failed to create display: A display is already created.");
    }

    mDisplay = &display;
}

DisplayManager::DisplayManager()
{
}

The addDisplay() method is called by another class like:

void Display::createDisplay()
{
    auto *manager = DisplayManager::getInstance();

    if(!manager)
    {
        throw std::runtime_error("No diplay manager.");
    }

    ALLEGRO_DISPLAY *display = al_create_display(width, height);

    if(!display)
    {
        throw std::runtime_error("Failed to create display");
    }

    manager->addDisplay(*display);
}

In addDisplay() method, when I do mDisplay = &display;, I get the following exception:

Unhandled exception at 0x75A818A2 in My_Executable.exe: Microsoft C++ exception: std::runtime_error at memory location 0x0073F66C.

The application is working as expected despite this exception. I can't quite figure out the reason for this exception.

EDIT 1:

I tried to put a try-catch:

try
{
    mDisplay = &display;
}
catch(const std::exception&)
{
// Couldn't reach this code.
}

When I tried this, strangest thing happened. I get the exact same exception and it is raised at the line that contains try...

EDIT 2:

Link to documentation on al_create_display(). It returns a raw pointer to a display.

EDIT 3:

I suspected that it's the assignment operator that is causing the issue. So I tried replacing my ALLEGRO_BITMAP *mDisplay with a std::vector<ALLEGRO_BITMAP *> and instead of doing mDisplay = &display, I did mDisplay.push_back(&display). Now, the exception disappeared. I really appreciate it if anyone can shed more light into it. May be the copy assignment operator is disabled?

Upvotes: 0

Views: 5255

Answers (1)

the boy
the boy

Reputation: 243

hope this can help you see the comment below:

void DisplayManager::addDisplay(ALLEGRO_DISPLAY &display)
{
    if(!mDisplay)
    {
        throw std::runtime_error("Failed to create display: A display is already created.");
    }

    mDisplay = &display; // dangerous to do this, mDisplay point to display
//if display is being destroy => mDisplay point to un-legal memory
}

look at where we call it

ALLEGRO_DISPLAY *display = al_create_display(width, height); // problem in here
 //if this function return object which will being destroyed later, then error happen

if(!display)
{
    throw std::runtime_error("Failed to create display");
}

manager->addDisplay(*display); // look at this, when we are out of this 
//and the object above is being destroy, mDisplay point to un-legal memory => exception

Upvotes: 1

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