C++链表insert_end()

Question

#include <iostream>

using namespace std;

class Node {
    friend class LinkedList;
private:
    int value;
    Node *pNext;
public:
    Node();
    Node(int);
    ~Node();
    
};

class LinkedList {
private:
    Node *pHead;
    Node *pCursor;
public:
    LinkedList();
    void insert_front(int);
    void insert_end(int);
    void insert_after(int, int);
    void delete_node();
    void displayList();
    void reverseSLL();
    int size();
    
};

int main(int argc, const char * argv[]) {
    
    LinkedList SLL;
    
    for(int i=1;i<6;i++) SLL.insert_end(i);
    
    return 0;
}

Node::Node() {
    pNext = NULL;
}
Node::Node(int val) {
    value = val;
    pNext = NULL;
}
Node::~Node() {
    
}
LinkedList::LinkedList() {
    pHead = NULL;
    pCursor = NULL;
}

void LinkedList::insert_front(int val) {
    if(size()==0) pHead = new Node(val);
    else if(size()>0) {
        pCursor = pHead;
        pHead = new Node(val);
        pHead->pNext = pCursor;
    }
    displayList();
    return ;
}
void LinkedList::insert_end(int val) {
    if(size()==0) pHead = new Node(val);
    else if(size()>0) {
        pCursor = pHead;
        while(pCursor!=NULL) pCursor = pCursor->pNext;
        Node *pNewNode = new Node(val);
        pCursor->pNext = pNewNode;
    }
    displayList();
}

void LinkedList::insert_after(int nth, int val) {
    pCursor = pHead;
    Node *pNewNode = new Node(val);
    for(int i=0;i<nth-1;i++) pCursor = pCursor->pNext;
    pCursor->pNext = pNewNode;
    displayList();
}

void LinkedList::delete_node() {
    int val = 0;
    cout<<"Enter a node you want to delete: "; cin>>val;
    pCursor = pHead;
    if(size()==0) return;
    else if(size()==1) delete pCursor;
    else if(size()>1) {
        while(pCursor->value != val) {
            cout<<pCursor->value;
            pCursor = pCursor->pNext;
        }
        if(pCursor->pNext== NULL) delete pCursor;
        else {
            pHead = pCursor->pNext;
            delete pCursor;
        }
    }
    displayList();
}

void LinkedList::displayList() {
    if(size()==0) return;
    else if(size()>0) {
        pCursor = pHead;
        while(pCursor!=NULL) {
            if(pCursor->pNext==NULL) {
                cout<<pCursor->value;
                break;
            }
            cout<<pCursor->value<<"->";
            pCursor = pCursor->pNext;
        }
    } cout<<endl;
}

void LinkedList::reverseSLL() {
    if(size()==0) return;
    else if(size()>0) {
        pCursor = pHead;
        int reversedArr[size()];
        for(int i=0;i<size();i++) {
            reversedArr[i] = pCursor->value;
            pCursor = pCursor->pNext;
        }
        for(int i=size()-1;i>=0;i--) {
            if(i==0) cout<<reversedArr[i];
            cout<<reversedArr[i]<<"->";
        } cout<<endl;
    }
}

int LinkedList::size() {
    int temp = 0;
    pCursor = pHead;
    while(pCursor != NULL) {
        temp ++;
        pCursor = pCursor->pNext;
    }
    return temp;
}

我正在尝试创建一个单链表，但在“insert_end()”函数中，我看到了分段错误。这个函数应该是在链表的末尾添加一个元素，然后打印出结果。

void LinkedList::insert_end(int val) {
    if(size()==0) pHead = new Node(val);
    else if(size()>0) {
        pCursor = pHead;
        while(pCursor!=NULL) pCursor = pCursor->pNext;
        Node *pNewNode = new Node(val);
        pCursor->pNext = pNewNode;
    }
    displayList();
}

我不知道我的问题是什么。我在我的其他函数中看到了这个分段错误。我应该解决什么问题？

Answer 1

while(pCursor!=NULL) pCursor = pCursor->pNext;

迭代 pCursor 直到它为 NULL

pCursor->pNext = pNewNode;

现在取消引用 NULL 指针。

你应该做什么？可能更早停止一个，迭代直到 pCursor->pNext 为 NULL，然后像您已经在做的那样将新的分配给 pCursor->pNext。

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