Elysian Shadows

Posted: **Sun Jan 11, 2009 5:54 am**

Maybe it's because I've been devving all night, but this is beyond me... Whenever I run my project, it gets to the constructor and calls updateStates(). It segfaults when trying to access the controller, whether it comes to the hat, axes, or buttons first.

typedef'd struct called myController...

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typedef struct
{
    Sint16 axis[4];
    bool button[12];
    Uint8 hat;
} myController;

class header called inputClass

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class inputClass
{
    private:
        SDL_Joystick* joystick;
        myController* controller;
    public:
        inputClass();
        ~inputClass();
        void updateStates();
        myController* getStates();
};

source code

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inputClass::inputClass()
{
    SDL_Init(SDL_INIT_JOYSTICK);
    joystick = SDL_JoystickOpen(0);
    //std::cout << "joystick open" << std::endl;
    updateStates();
}

void inputClass::updateStates()
{
    for(int i = 0; i < 4; i++)
    {
        controller->axis[i] = SDL_JoystickGetAxis(joystick, i);
    }
    for (int i = 0; i < 12; i++)
    {
        controller->button[i] = SDL_JoystickGetButton(joystick, i);
    }
    controller->hat = SDL_JoystickGetHat(joystick, 0);
}

Posted: **Sun Jan 11, 2009 7:28 am**

The 'controller' pointer has probably not been initialized.
But to sidestep that problem you could just have this:

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class inputClass
{
    private:
        SDL_Joystick* joystick;
        myController controller; // value instead of pointer
    public:
        inputClass();
        ~inputClass();
        void updateStates();
        myController* getStates();
};

and this

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void inputClass::updateStates()
{
    for(int i = 0; i < 4; i++)
    {
        controller.axis[i] = SDL_JoystickGetAxis(joystick, i);
    }
    for (int i = 0; i < 12; i++)
    {
        controller.button[i] = SDL_JoystickGetButton(joystick, i);
    }
    controller.hat = SDL_JoystickGetHat(joystick, 0);
}

and then implement getStates like this:

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myController * inputClass::getStates()
{
    return &controller;
}

Keep in mind that the pointer that is returned by this implementation of getStates is only valid as long as the instance of inputClass still exists.

Posted: **Sun Jan 11, 2009 1:11 pm**

Thank you for pointing that out. After thinking about what you said, and some scroogling, I've implemented an initializer list. (doing so for a derived class of a similar set-up was a pain)

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inputClass::inputClass() : controller(new myController)
{
    SDL_Init(SDL_INIT_JOYSTICK);
    joystick = SDL_JoystickOpen(0);
    //std::cout << "joystick open" << std::endl;
    updateStates();
}

Elysian Shadows

RESOLVED:segfault error; help please?

RESOLVED:segfault error; help please?

Re: segfault error; help please?

Re: segfault error; help please?