内存位置处的Microsoft C ++异常runtime_error(代码0x75A818A2)

时间:2019-04-19 11:03:02

标签: c++ exception

我有以下类定义:

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;
};

该类的实现是:

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()
{
}

addDisplay()方法由另一个类调用,例如:

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);
}

addDisplay()方法中,当我执行mDisplay = &display;时,出现以下异常:

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

尽管有此例外,应用程序仍按预期运行。我不太清楚发生此异常的原因。

编辑1:

我尝试放入try-catch:

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

当我尝试这样做时,最奇怪的事情发生了。我得到了完全相同的异常,它在包含try ...

的行中引发

编辑2:

链接到al_create_display()上的文档。它将原始指针返回到显示器。

编辑3:

我怀疑是导致问题的原因是赋值运算符。因此,我尝试将ALLEGRO_BITMAP *mDisplay替换为std::vector<ALLEGRO_BITMAP *>,而没有做mDisplay = &display,而是做了mDisplay.push_back(&display)。现在,异常消失了。如果有人能给予更多启示,我真的很感激。可能是复制分配运算符被禁用了吗?

1 个答案:

答案 0 :(得分:0)

希望这可以帮助您查看以下评论​​:

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
}

看看我们怎么称呼它

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