c++ - 链表程序崩溃

Question

好吧，我正在尝试用很少的代码编写一个链表(一个非常简单的链表)。这是我的代码:

#include <iostream>

using namespace std;

class node
{
public :

    int data = 0;

    node* next;
};

node node_obj;

int main()
{
    node* head;
    node* node_pointer = head;
    node_pointer = node_obj.next;
    node_pointer->data = 4;
    node_pointer = node_obj.next;
    node_pointer->data = 5;
    node_pointer = node_obj.next;
    node_pointer->data = 6;
    node_pointer = node_obj.next;

    return 0;
}

我一开始只是想让它工作，这就是为什么没有添加、打印或删除功能。

无论如何，每次我运行该程序时它都会崩溃，并且我会收到错误代码 C0000005。

据我所知，这是一个指示内存访问冲突的错误，但我找不到解决方案。更新:我更改了我的代码，现在它看起来像这样(仅包括更改的部分):

class node
{
public :
    node();
    int data = 0;
    node* next;
};
node::node()
{
    next = new node;
}

所以现在我有一个初始化的"new"指针，错误代码更改为 c00000fd

Answer 1

首先，在提出此类问题之前，您应该使用调试器。你代码中的问题是:

node node_obj;

int main()
{
    node* head;
    node* node_pointer = head; // Warning: dead storage. You never use the value you initialized here.
    node_pointer = node_obj.next; // node_obj.next was never initialized, so now node_pointer points nowhere.
    node_pointer->data = 4; // And here you use nowhere-pointing pointer to 
    // access structure member. According to the Standard,
    // it's [undefined behavior][1] which in practice usually leads to application crash.
    // All subsequent lines suffer from the same issue.
    node_pointer = node_obj.next;
    node_pointer->data = 5;
    node_pointer = node_obj.next;
    node_pointer->data = 6;
    node_pointer = node_obj.next;

    return 0;
}

可能你想写这样的东西:

node *head;

int main()
{
    head = new node;
    node *node_pointer = head;
    node_pointer->data = 4;
    node_pointer->next = new node;
    node_pointer = node_pointer->next;
    node_pointer->data = 5;
    node_pointer->next = new node;
    node_pointer = node_pointer->next;
    node_pointer->data = 6;
    node_pointer->next = nullptr; // List end marker.
    return 0;
}