带有 boost shared_ptr 的树

Question

我创建了这个简单的程序来学习 shared_ptr

using namespace std;
 #define Yes 1
 #define No 0

class Node
{
public:
boost::shared_ptr<Node> left;
boost::shared_ptr<Node> rigth;
int nVal;
Node();
Node(int);
~Node();
int getVal(void);
void setVal(int);

 };

方法

Node::Node()
{
cout << "creating node empty" << endl;
nVal = 0;
left.reset();
rigth.reset();

}

Node::~Node() 
{
cout << "entering destructor"  << nVal << endl;
}

Node::Node(int n)
{
cout << "creating node with value" << n << endl;
nVal = n;
left.reset();
rigth.reset();
}

int Node::getVal(void)
{
cout << "returning value" << endl;
return this->nVal;
}

void Node::setVal(int n)
{
cout << "setting value" << endl;
nVal = n;
}

树

  class Tree 
   {
  public:
 boost::shared_ptr<Node> root;
  Tree();
  ~Tree();
  void findParent(int n, int &found, boost::shared_ptr<Node> &parent);
  void add(int n);
  void post(boost::weak_ptr<Node> q);
  void del(int n);

  };

Tree::Tree()
{
root.reset();
}

 Tree::~Tree()
{
cout << "deleting tree" << endl;
}

树找到父节点

void Tree::findParent(int n, int& found, boost::shared_ptr<Node> &parent)
{
   boost::shared_ptr<Node> q;
  found = No;

 cout << "looking parent of" << n << endl;
 if(parent.use_count() == 0)
 {
  cout << "not found" << endl;
  return;
  }

q=parent;

 while (!q.use_count())
{
  if( q->nVal == n)
  {
      cout << "found" << endl;
      found = Yes;
      return;

  }

  if (q->rigth->nVal)
  {
      cout << "looking to the rigth" << endl;
      parent = q;
      q = q->left;
  }
  else
  {
      cout << "looking to the left" << endl;
      parent = q;
      q = q->rigth;
  }
 }
}

树添加

void Tree::add(int n)
 {
 int found;

boost::shared_ptr<Node> parent;
findParent(n, found,parent);
if(found == Yes)
{
    cout << "no such node exist" << endl;
}

else
{

    boost::shared_ptr<Node> t(new Node(n));  
    t->rigth.reset();
    t->left.reset();

    if (parent.get()== 0)
    {
        parent = t;
    }
    else
    {
        parent->nVal > n ? parent->left = t : parent->rigth = t;
    }
}
}

主要：

int THREADS_HOW_MANY = 0;

int main()
{
Tree bt;
bt.add(10);
bt.add(4);
bt.add(12);
bt.add(2);
bt.add(8);
bt.add(15);
bt.add(15);



return 0;
}

现在 q 是，为什么不工作，为什么给出这个输出：

  empty constructor only the root is reset
  looking parent of10
  not found
  creating node with value10
  entering destructor10
  looking parent of4
  not found
  creating node with value4
  entering destructor4
  looking parent of12
  not found
  creating node with value12
  entering destructor12
 looking parent of2
 not found
  creating node with value2
 entering destructor2

现在修复它是 diff 似乎节点只是被创建和删除而不是添加到树为什么？？

Answer 1

这是你的代码：

// 从树::添加 boost::shared_ptr t(新节点(n)); boost::shared_ptr parent(新节点(n)); 找到父母（n，找到，父母）； // 从树::findParent boost::shared_ptr q(新节点(n));

因此，程序根据要求为每个值创建节点 3 次。 shared_ptr 确保每个节点都被正确销毁，因此节点析构函数也被调用了 3 次。