避免在使用链接列表从 deque 中删除最后一个节点时出现内存泄漏

Question

对于我的家庭作业，我需要制作从Deque中添加(附加(和删除(服务(节点的方法。但是，当尝试为最后一个节点提供服务时，我遇到了内存泄漏，因为我不知道如何检索不再用于系统的节点。 下面是该方法的代码。

void Deque::serveAtRear(int &x)
{
if(empty())
{
cout << "Fila Vazia" << endl;
exit(0);
}
else
{
DequePointer q;         //Pointer before p
q = head;               //q starts at the deque's head
p = head->nextNode;     //Pointer for the next node
if(q->nextNode==NULL)   //If there's only one node
{
x = q->entry;        //x will receive the value of the removed node to print it afterward
head = tail = NULL;
delete p;            //I don't know if I'm using the "delete" right
}
else
{
while(p->nextNode != NULL)
{
p = p->nextNode;
q = q->nextNode;
if(p->nextNode==NULL)
{
q->nextNode=NULL;
}
}
x = p->entry;
delete p->nextNode;
}
delete q->nextNode;
}
}

要添加节点，我有此方法：

void Deque::appendAtFront(int x)
{
if(full())
{
cout << "FULL" << endl;
exit(0);
}
else
{
p = new DequeNode;
p->entry=x;
if(p == NULL)
{
cout << "Can't insert" << endl;
exit(0);
}
else if(empty())
{
head = tail = p;
p->nextNode=NULL;
}
else
{
p->nextNode=head;
head = p;
}
}
}

我也不能使用"deque"lybrary

Answer 1

如何避免泄漏的通用答案是：避免手动分配内存。

例如，您可以使用智能指针，例如std::unique_ptr，而不是打电话new DequeNode打电话给std::make_unique<DequeNode>().然后，编译器将指出需要调整代码的地方，因为您将限制自己，以便每个DequeNode同时仅由一个unique_ptr拥有。示例弹出函数(其中head和DequeNode.nextuniuque_ptrs(基于您的 serveAtRear：

if (!head)
{
return;
}
DequeNode* q;          //Pointer before p 
DequeNode* p;          //will be tail eventually 
q = head.get();        //q starts at the deque's head 
p = q->next.get();     //Pointer for the next node 
if(!p)   //If there's only one node 
{       
x = q->entry; //x will receive the value of the removed node to print it afterward 
head.reset(); // hear we release DequeNode pointed by head
}       
else    
{       
while(p->next) 
{       
q = p;  
p = q->next.get(); 
}       
x = p->entry; 
q->next.reset(); // here we release tail (i.e. p)
}       

当然，推动的实施需要采用太:)。