Deque problem with shared_ptr

[Luke Murray]

Hey all. I have a deque<MenuPtr> and MenuPtr is typedef of shared_ptr<Menu>. Not sure what i am doing wrong but I get the following error message when i run deque.clear();

Unhandled exception at 0x004590e9 in menu.exe: 0xC0000005: Access violation reading location 0xfaaafaa2.

What is happening in that method? It remove the shared pointers from the list and anything else? Or am I doing something really dumb? Cheers. Luke

[Jack Puppy]

You'd have to post your code, I can't tell much from what you've posted, other than it's a bad pointer exception. I just whipped this and it worked fine.

// testsharedptr.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <boost/shared_ptr.hpp>
#include <deque>
#include <crtdbg.h>

class Menu
{
int m_x;
int m_y;

public:
Menu(int x, int y) : m_x(x), m_y(y)
{}
Menu(const Menu& menu)
{*this = menu;}
virtual ~Menu()
{}
Menu& operator=(const Menu& menu)
{
if (this != &menu)
{
m_x = menu.m_x;
}
return (*this);
}
};

typedef boost::shared_ptr<Menu> MenuPtr;

int _tmain(int argc, _TCHAR* argv[])
{
_CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF);

Menu\* one = new Menu(1,2);
Menu\* two = new Menu(3,4);

std::deque<MenuPtr > myDeque;
myDeque.push\_front(MenuPtr(one));
myDeque.push\_back(MenuPtr(two));

return 0;

}

:suss: Pssst. You see that little light on your monitor? That's actually a government installed spy camera. Smile and wave to big brother!

[M Mehrdad M]

i had this problem before. it is because of size of Entities you En/Deque in Queue. it is not the same value that queue thinks! for example you Enque 5 Byte Entities But Que try to dequeue 10 Bytes Entities.;P M.Mehrdad.M

[Luke Murray]

Sorry don't have the code on me right now. I'll reply again later when at home. But i'll try to get it across now. I have a Menu class that contains a deque of other MenuPtr's as you can add Menu object to Menu objects. One way is vis Menu::add(MenuPtr& menu); or Menu::add(Menu* menu); So in another class I have a Menu object which I add other Menu object to, etc. I have been messing around with both, but when I use the Menu* one I never delete the pointer I created so that should cause a problem. So I get the error when I do Menu::clear which clears the list of child menus. or when I quit the program as in the deconstrutor it also call clear(). Hope this makes it clear. I'll be back home later and look at the code again. Thanks Luke

[Luke Murray]

Hmm ok. Any idea of why this would happen. Or how did you overcome the problem? Luke