please explain it.

the following code produces a run time error. but i don't really understand How?

Code:

---

#include <iostream>
using namespace std;

class ID {
        int id;
public:
        ID(int i) { id = i; }
        void del() { delete this; }
        int getID() { return id; }
};

int main()
{
        ID id(10);
        id.del();
        cout << id.getID() << endl;

        return 0;
}

---

Code:

---

        void del() { delete this; }

---

This is like sitting on the branch you are cutting from the tree [cutting inside yourself].
http://www.srpska-mreza.com/History/...n/self-cut.jpg

You should NEVER do "delete this".

--
Mats

You could get away with it, but it certainly never is a good thing, especially if allocated on the stack.
You have two undefined behavior there. Delete this on a class allocated on the stack and trying to access the class's contents after it's been deleted. No wonder you get a crash.

As Elysia correctly points out, doing "delete this" when "this" is a pointer to an object that was not created with new, then you are ALSO performing something bad in this situation - that would definitely cause a big problem in one way or another. I should have spotted that too.

But it's also not particularly meaningful to do delete this in a case where the object has been allocated using new.

--
Mats

Quote:

---

Originally Posted by matsp

But it's also not particularly meaningful to do delete this in a case where the object has been allocated using new.

---

I think that depends. You can find solutions where it might work, such as MFC's CWinThread, which, by default, deletes itself when the thread has finished executing. But I would like to rely more on smart pointers, however.

Thanks matsp and Elysia!
I was thinking ... if I don't access any data member after doing delete this then it will work fine!
But in this case, as Elysia pointed, that will delete a memory which was never newed.
So I think it will still fail.

I could say yes to both statements. But delete itself can be a dangerous practice, since it can leave a dangling pointer somewhere.

You will. But you actually do access the data members.