我总是遇到分段错误

Question

我总是在 C++ 中遇到 10861 分段错误（核心已转储）抱歉，我来自 java 它总是说 head -> next 如何分配内存给那个

#include <iostream>
using namespace std;

class Node
{
public:
  int data;
  Node *next;
};

class lisp
{
public:
  Node *head;
  void create(int d)
  {
    this->head->data = d;
    cout << head->data;
  }
  void insert(int d)
  {
    Node *n = head;
    Node *add;
    add->data = d;
    cout << head -> next << endl; 
  }
};

int main()
{
  lisp test;
  test.create(0);
  test.insert(1);
  test.insert(2);
  return 0;
}

Answer 1

您需要先初始化指针，然后再为其赋值。因此，您需要 Node *add = new Node(); 才能这样做。假设您想将一个新节点附加到列表中，也许您需要跟踪列表的尾部 (Node *tail)。每次添加新节点时，都会移动 tail.

#include <iostream>
using namespace std;

class Node
{
public:
  int data;
  Node *next;
};

class lisp
{
public:
  Node *head;
  Node *tail;
  void create(int d)
  {
    head = new Node();
    head->data = d;
    tail = head;
    cout << head->data << endl;
  }
  void insert(int d)
  {
    Node *add = new Node();
    add->data = d;
    add->next = NULL;
    tail->next = add;
    tail = add;
    cout << add->data << endl; 
  }
};

int main()
{
  lisp test;
  test.create(0);
  test.insert(1);
  test.insert(2);
  return 0;
}

我总是遇到分段错误

i am always getting segmentation fault

c++

memory

segmentation-fault

allocation