Deleting an element from a vector of object pointers allocated on the stack

Question

I have a vector of Object pointers. I want to be able to delete those objects and free the memory taken up by those objects.

What I have currently is this:

This is the vector that contains the object pointers:

std::vector<Ball*> List;

This is the function that deletes the element in the vector and frees the memory:

void BallManager::DeleteBall(int id) 
{
    List[id]->~Ball(); //Not sure if this is needed
    delete List[id];
    List[id] = NULL;
    List.erase(List.begin()+id);
}

My question is do I need to also call the destructor for the object or is that taken care of by delete?

I highly recommend a vector of smart pointers instead. You won't need to worry about managing the pointer's memory if you do; simply calling erase would deallocate the memory and everything as well. — chris

billz billz · Accepted Answer · 2012-12-22T04:17:31

If you want to delete pointer element, delete will call object destructor. No need to call List[id]->~Ball() also no need to set pointer to NULL as you are going to erase the element anyway.

std::vector<Ball*> List;

void BallManager::DeleteBall(int id) 
{
    if (id < List.size())   // should check id is still in range
    {  
      delete List[id];
      List.erase(List.begin()+id);
    }
}

Strongly recommand you use smart pointer as Chris mentioned, then you don't need to worry about deleting object pointer when you delete element from STL container, demo as below:

  std::vector<std::shared_ptr<Ball> > List;
  void BallManager::DeleteBall(int id) 
  {
     if (id < List.size())   // should check id is still in range
     {  
        List.erase(List.begin()+id);
     }
  }

Deleting an element from a vector of object pointers allocated on the stack

3 Answers