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; }
This is like sitting on the branch you are cutting from the tree [cutting inside yourself].Code:void del() { delete this; }
http://www.srpska-mreza.com/History/...n/self-cut.jpg
You should NEVER do "delete this".
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Mats
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.
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.
Originally Posted by Adak
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.
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Mats
Compilers can produce warnings - make the compiler programmers happy: Use them!
Please don't PM me for help - and no, I don't do help over instant messengers.
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.
All the buzzt!
CornedBee
"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
- Flon's Law
