Cant static cast class to integer

Question

Why am i getting a error when i try to static cast a element* to an int

typedef Element* ElementPtr

int Element::getVP (ElementPtr item)
{
return static_cast <int>(item); // I have a class called Element
}

Pointers don't convert to integers. Pointers are not integers. Pointers are pointers. Why do you need to do this? You probably don't. This means that you don't need a `void*`, either. — Lightness Races in Orbit, Feb 10 '13 at 10:56
For a pointer, `void *` is preferred above `int`, but ... what Ed said. — Bernhard Barker, Feb 10 '13 at 10:57
i am trying to have a function which use a element pointer to point to the int value of a element class — Computernerd, Feb 10 '13 at 10:57
@Computernerd: What is "the int value of a element class"? Tell us what you are trying to do, and not how you've decided to do it. — Lightness Races in Orbit, Feb 10 '13 at 10:58
Sorry, but I think you have to make two steps back first and then tell us what it is you want to achieve. As for how you're trying to achieve it, all I know is that this is wrong. — Ulrich Eckhardt, Feb 10 '13 at 10:59
How is `Element` defined and what would its `int` representation be (once you dereference the pointer)? — johnsyweb, Feb 10 '13 at 11:01
thanks everyone for their help, i got it figured out already thanks — Computernerd, Feb 10 '13 at 11:10

billz · Answer 1 · 2013-02-10T11:14:56.597

Not really sure what's your question, but I feel you want implicit conversion function. To convert Element to int, you want operator int()

struct Element
{
  operator int()
  {
    return i;
  }
  int i;
};

int Element::getVP (Element* item)
{
  return (*item); // I have a class called Element
}

But it's still not clear why you need getVP in Element class.

It' just to show you how to convert struct/class to int type. I'll delete my answer if it's not what you want.

score 1 · Answer 2 · answered Feb 10 '13 at 11:03

Assuming you're trying to get a int from the Element and you have already overloaded the cast operator of the Element class like so:

operator int() { return m_some_int; }

you can use (assuming item is a pointer)

return (int)(*item);

Instead, if you're trying to get the address of the pointer you can do the following:

std::size_t Element::get_address(Element* item)
{
    return reinterpret_cast<std::size_t>(item);
}

Cant static cast class to integer

2 Answers2