上面的代码已成功编译,但是当我尝试运行它时,它会抛出malloc错误:
malloc: *对象0x7fdbf6402800的错误:未释放指针被释放 * 在malloc_error_break中设置断点以进行调试
看起来我试图销毁一些未初始化的对象,但我无法弄清楚如何修复它。
#include <iostream>
template <class T>
class Node {
public:
T data;
Node<T>* next;
Node<T>* prev;
Node(): data(), next(nullptr), prev(nullptr) { }
Node(T dt): data(dt), next(nullptr), prev(nullptr) { }
Node(T dt, Node* n): data(dt), next(nullptr), prev(n) { }
T get() { return data; }
};
template <class T>
class Stack {
public:
Node<T>* head;
Node<T>* tail;
Stack(): head(nullptr), tail(nullptr) { }
~Stack() {
Node<T>* temp = head;
while(temp) {
delete temp;
temp = temp->next;
}
}
bool empty() const;
Stack& push(T);
Stack& pop();
};
template <class T>
bool Stack<T>::empty() const {
return head == nullptr;
}
template <class T>
Stack<T>& Stack<T>::push(T x) {
if (head == nullptr) {
head = new Node<T>(x);
tail = head;
}
// It seems that problem occurs here
else {
Node<T>* temp = tail;
tail = new Node<T>(x, tail);
tail->prev = temp;
temp->next = tail;
}
return *this;
}
template <class T>
Stack<T>& Stack<T>::pop() {
if (!head) {
return *this;
}
else if (head == tail) {
delete head;
head = nullptr;
tail = nullptr;
}
else {
Node<T>* temp = tail;
delete tail;
tail = temp;
}
return *this;
}
int main() {
Stack<int> istack;
istack.push(5);
istack.push(3);
istack.push(4);
istack.push(7);
istack.pop();
}
答案 0 :(得分:2)
如果你看看你的析构函数 - 你有错误
~Stack() {
Node<T>* temp = head;
while(temp) {
delete temp;
temp = temp->next; // Here temp is no longer a valid pointer
// You have just deleted it!
}
}
所以写下面的
~Stack() {
while(head) {
Node<T>* temp = head->next;
delete head
head = temp;
}
}
编辑
正如所指出的,pop
需要一些工作。即。
template <class T>
Stack<T>& Stack<T>::pop() {
if (!head) {
return *this;
}
Node<T>* temp = tail->next;
delete tail;
tail = temp;
if (!tail) {
head = nullptr;
}
return *this;
}