CODEWITHSUNDEEP
c++pointersvectordelete-operator
derlange
derlange

Reputation: 13

How to delete multiple added pointer of a vector?

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?

Upvotes: 1

Views: 191

Answers (3)

kunal
kunal

Reputation: 966

I think the exception is due to the fact that you are allocating the memory only once in "Bar* b = new Bar()" and you are deleting it twice.You should allocate twice and then your code will not throw an exception.

Upvotes: 0

Kerrek SB
Kerrek SB

Reputation: 477040

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.)

Upvotes: 2

Puppy
Puppy

Reputation: 146930

Use a shared_ptr. You can find this in C++0x, TR1, or Boost. shared_ptr knows how many pointers still point to an object and only delete it when it's the last one.

Upvotes: 3

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