C++内存泄漏形式将数据插入链表

Question

我需要为我的链接列表使用 unique_ptr 或 shared_ptr，但我仍然遇到内存泄漏。对于这种情况，我将所有成员数据保留为 public。第一次插入链表不会导致任何内存泄漏，但随着 for 循环的继续，每次我将一个对象作为数据插入链表时，调试器会显示更多的内存泄漏。我不知道是什么导致了如此多的内存泄漏。会不会是某些共享点引起的？

    template <typename T>
    class Node
    {
    public:
       T data;
       shared_ptr<Node<T>> next;
       shared_ptr<Node<T>> prev;

    public:
       Node() { next = NULL; prev = NULL; data = 0; }
       Node(T value) { next = NULL; prev = NULL; data = value; }
       T getData() { return data; }

    };

  template <typename T>
  class DoubleLinkedList
  {
  public:
      shared_ptr<Node<T>> head;
      shared_ptr<Node<T>> tail;
  public:
      DoubleLinkedList()
     {
         head = NULL;
         tail = NULL;
         total = 100;
         for (int i = 0; i < total; i++)
         {
            Insert(objectgetsinsertedhere);
         }
     }


void Insert(T data)
{
    shared_ptr<Node<T>> rover = NULL;
    T value(data);
    if (head == NULL)
    {
        head = make_shared<Node<T>>(data);
        tail = head;
    }
    else
    {
        shared_ptr<Node<T>> nu = make_shared<Node<T>>(data);
        nu->prev = tail;
        if (head == tail)
            head->next = nu;
        tail->next = nu;
        tail = nu;
    }
}
};

编辑:这是调试器显示为内存泄漏的一部分。

Detected memory leaks!
Dumping objects ->
{211} normal block at 0x005CF798, 8 bytes long.
Data: <x \     > 78 98 5C 00 00 00 00 00 
{210} normal block at 0x005CF258, 8 bytes long.
Data: <\ \     > 5C 98 5C 00 00 00 00 00 
{209} normal block at 0x005CF1B0, 8 bytes long.
Data: <@ \     > 40 98 5C 00 00 00 00 00 
{205} normal block at 0x005C9830, 136 bytes long.
Data: <H               > 48 A9 0C 00 01 00 00 00 01 00 00 00 CD CD CD CD 
{191} normal block at 0x005CF3A8, 8 bytes long.
Data: <  \     > A8 DB 5C 00 00 00 00 00 
{190} normal block at 0x005CF0D0, 8 bytes long.
Data: <  \     > 8C DB 5C 00 00 00 00 00 
{189} normal block at 0x005CF060, 8 bytes long.
Data: <p \     > 70 DB 5C 00 00 00 00 00 
{185} normal block at 0x005CDB60, 136 bytes long.
Data: <H               > 48 A9 0C 00 01 00 00 00 01 00 00 00 CD CD CD CD 
Object dump complete.

Answer 1

问题是您的共享指针中有一个所有权循环。这使得内存不会自动释放，因为总是至少有一个所有者，即使链表本身已被销毁。解决这个问题的一种方法是只对 next 指针使用共享指针，而不是 prev 指针:

template <typename T>
class Node
{ 
  public:
    T data;
    shared_ptr<Node<T>> next;
    Node<T> *prev;

  public:
    Node() { next = NULL; prev = NULL; data = 0; } 
    Node(T value) { next = NULL; prev = NULL; data = value; }
    T getData() { return data; }

};

这会阻止所有权循环。列表拥有头部，头部拥有第二个元素，等等。当列表被销毁时，头部没有所有者，所以头部被破坏，现在第二个元素没有所有者，所以它得到销毁等