c++ - 池类抛出错误

Question

我正在尝试实现一个维护链表节点池的池类

虽然分配和释放工作正常，但析构函数抛出异常。

class Pool {
public:

  Pool ();

  ~Pool ();

  tEmployee *GetFromPool (void);

  void GiveToPool (tEmployee * pNode);

  void  PrintPoolSize ();

private:
  int vTop;                        
  tEmployee *vPool;                 
  tEmployee *vDeleted;
};

下面是函数的实现

Pool::Pool () 
  :vTop (0), vDeleted (NULL)
{
  vPool = new tEmployee[MAX_POOL];
}

tEmployee* Pool::GetFromPool (void) 
{
  if (vDeleted) {
    tEmployee * temp = vDeleted;
    vDeleted = vDeleted->next;

    return temp;
  }

  if (vTop == MAX_POOL) {

    vPool = new tEmployee[MAX_POOL];
    vTop = 0;
  }

  return vPool + vTop++;
}

void Pool::GiveToPool (tEmployee * pNode)
{
  pNode->next = vDeleted;

  vDeleted = pNode;
}

Pool::~Pool ()
{   
  tEmployee *curr = vDeleted;
  tEmployee *next = 0;

  while (curr) {

    next = curr->next;
    delete curr;    //This line is throwing exception on the second iteration of the loop
    curr = next;
  }

  delete [] vPool;
}

是否是由于堆损坏？

Answer 1

您分配一组员工:

vPool = new tEmployee[MAX_POOL];

然后错误地尝试单独删除它们:

delete curr; // Don't do this

在正确删除数组之前:

delete [] vPool;

作为一般规则，每个new必须匹配一个delete；您没有单独新建员工，所以不要单独删除他们。

您还需要维护一个指向您分配的所有数组的指针列表，以便您可以在析构函数中将它们全部删除；目前，除了你分配的最后一个，你把所有的都泄露了。我会建议这样的事情:

std::vector<tEmployee *> vPool; // store all allocated blocks

tEmployee* GetFromPool() {
   if (vDeleted) {
       tEmployee * temp = vDeleted;
       vDeleted = vDeleted->next;
       return temp;
  }

  if (vTop == MAX_POOL) {    
    vPool.push_back(new tEmployee[MAX_POOL]); // add new block to collection
    vTop = 0;
  }

  return vPool.back() + vTop++;
}

~Pool() {
    for (size_t i = 0; i < vPool.size(); ++i)
        delete vPool[i];
}