two types of heap allocated objects--any benefit?

From:

newbie <mitbbsmj@yahoo.com>

Newsgroups:

comp.lang.c++

Date:

2 May 2007 17:50:25 -0700

Message-ID:

<1178153424.965555.199230@n76g2000hsh.googlegroups.com>

Let's see two different usage of an STL container. I see (2) more
often when reading code over (1), dose that give any benefit or it's
purely a coding preference?

Also, please see the (3), I see (3) often in ppl' code, does that give
any benefit over (2)

Thanks for answering in advance:)

-------------------------------
class MyData;
class Example;

int main() {
  Example example;
  for(int i = 0 ; i < HUGE_NUM; i++) {
     example.Enque(MyData(i));
  }
}

class MyData {
  public:
    MyData(int i) {data = i; }
    int data;
}

// (1) The first Example definition:
class Example {
public:
  Example() {};
  ~Example() {};
  Enque(MyData a) { storage.push_back(a); }
private:
  deque<MyData> storage;
}

// (2) We can define Example alternatively, like the following
class Example {
public:
  Example() { storage = new deque<MyData>; }
  ~Example() { delete storage; };
  Enque(int a) { storage->push_back(a); }
private:
  deque<MyData> *storage;
}

------------------------------
------------------------------

(3) The third approach doing similar thing.
class MyData;
class Example;
int main() {
  Example example;
  for(int i = 0 ; i < HUGE_NUM; i++) {
     MyData* a = new MyData(i);
     example.Enque(a);
  }
}

class MyData {
  public:
    MyData(int i) {data = i; }
    int data;
}

class Example {
public:
  Example() { storage = new deque<MyData>; }
  ~Example() {
    while (!storage->empty()) {
        MyData* a = storage->pop_front();
        delete a;
    }
    delete storage;
  }
  Enque(MyData *a) { storage->push_back(a); }
private:
  deque<MyData*> *storage;
}