/**

* http://suanfa.blogspot.com/2010/10/auto-ptr.html

*

*/

#include <iostream>

#include <vector>

#include <memory>

using namespace std;

int main() {

int *p1 = new int(3);

auto_ptr<int> p2(p1);

// still works because copy from pointer to smart pointer

cout<<*p1<<endl;

cout<<*p2<<endl;

auto_ptr<int> p3(new int(4));

auto_ptr<int> p4(p3);

cout<<*p4<<endl;

// cout<<*p3<<endl; // Segmentation fault, coz p3 is NULL

vector<auto_ptr<int> > v;

v.push_back(p1); // error, can not push int * to auto_ptr

v.push_back(p4); // doesn't compile

// auto_ptr has a copy constructor with a non-const parameter,

// so the compiler can't call it from vector::push_back() since the latter has const parameter.

// The reason is when you initialize one auto_ptr instance from

// another the new instance disconnects the object from

// the other instance and connects it to self

// so avoid a dangling pointer situation when one instance deletes the object and

// the other still holds a pointer to it.

return 1;

}