Question

I have a vector with some (among other classobjects) multiple added objects

class Foo {
  ...
  vector<Bar*> v;
  Bar* b = new Bar();
  v.push_back(b);
  v.push_back(b);
  ...
}

in Foo’s destructor I do

for (vector<Bar*>::iterator it = v.begin(); it != v.end(); ++it)
    delete *it;

this causes an exception on the second iteration, because the object is already deallocated: “Access violation reading location 0xfeeefee2.”

How do I solve this problem?

Answer 1

Solve it by not using the terrible idea of storing raw pointers in a container. Instead, use a container of smart pointers:

#include <memory>
#include <vector>

typedef std::shared_ptr<Foo> FooPtr;

std::vector<FooPtr> v;

FooPtr b(new Bar());                 // #1

v.push_back(b);
v.push_back(b);
v.push_back(b);

// C++0x: even better method:
auto c = std::make_shared<Bar>();     // #2
v.push_back(c);
v.push_back(c);

v.push_back(std::make_shared<Bar>()); // #3

// Three distinct allocations of a Bar object have happened, #1, #2, and #3.

// No explicit deletions!

If you don’t have C++0x, use the TR1 library:

#include <tr1/memory>
typedef std::tr1::shared_ptr<Foo> FooPtr;

(You don’t have make_shared in that case, because that’s a new gimmick using rvalue references and forwarding.)