Question

我试图了解C ++，我遇到了内存管理和析构函数概念的问题。我曾尝试使用链接列表编写一个Queue实现，我正在接收＆＃34; Aborted（Core Dumped）＆＃34;我尝试在析构函数方法中删除链表节点时出现错误消息（粗体）。如果有人知道我做错了什么，请告诉我！

这是我的析构函数方法的代码：

template <class T>
Queue<T>::~Queue(){
  Node<T> *currHead = head;
  while(currHead != NULL){
    Node<T> *nextHead = currHead->next;
    delete currHead;
    currHead = nextHead;
  }
  Node<T> *currTail = tail;
  while(currTail != NULL){
    Node<T> *nextTail = currTail->next;
    delete currTail;
    currTail = nextTail;
  }
}

此处参考我的完整链表列表实现：

template <class T>
class Node{
public:
  T data;
  Node<T> *next=NULL;
};

template <class T>
class Queue{
public:
  Queue();
  ~Queue();
  void push(T);
  T pop();
  int size=0;
  Node<T> *head=NULL;
  Node<T> *tail=NULL;
};

template <class T>
Queue<T>::Queue(){}

template <class T>
Queue<T>::~Queue(){
  Node<T> *currHead = head;
  while(currHead != NULL){
    Node<T> *nextHead = currHead->next;
    delete currHead;
    currHead = nextHead;
  }
  Node<T> *currTail = tail;
  while(currTail != NULL){
    Node<T> *nextTail = currTail->next;
    delete currTail;
    currTail = nextTail;
  }
}

template <class T>
void Queue<T>::push(T data){
  Node<T> *node = new Node<T>;
  node->data = data;
  if(head == NULL){
    head = node;
  }else{
    tail->next = node;
  }
  tail = node;
  size++;
}

template <class T>
T Queue<T>::pop(){
  if(size == 0){
    throw "Empty Queue";
  }else{
    Node<T> *oldHead = head;
    T oldData = oldHead->data;
    head = head->next;
    size--;
    delete oldHead;
    return oldData;
  }
}

编辑：

我还尝试了以下析构函数的定义，但我得到了同样的错误：

template <class T>
Queue<T>::~Queue(){

  while(head != NULL){
    Node<T> *currHead = head;
    head = head->next;
    delete currHead;
  }

  while(tail != NULL){
    Node<T> *currTail = tail;
    tail = tail->next;
    delete currTail;
  }
}

Answer 1

在析构函数的第一部分中，您将删除从head开始的所有列表项。在析构函数的第二部分中，您尝试使用尾部保留的指针再次删除最后一个列表项，但它已在第一部分中删除。

Answer 2

删除指针不会更改指针或指向已删除内存的任何其他指针：

#include <iostream>

int main() {
    int* head = new int[4];
    int* tail = head;

    delete head;

    std::cout << "head = " << (void*)head << ", tail = " << (void*)tail << "\n";
}

您的代码应该是：

template<typename T>
Queue<T>::~Queue(){
  Node<T> *currHead = head;
  while(currHead != nullptr){
    Node<T> *nextHead = currHead->next;
    delete currHead;
    currHead = nextHead;
  }
  head = tail = nullptr;
  size = 0;
}

或者你的pop功能是否有效：

template<typename T>
Queue<T>::~Queue() {
    while (size)
        pop();
}

C ++ LinkedList队列实现和析构函数错误：＆＃34; Aborted（Core Dumped）＆＃34;

2 个答案: