在链接列表的末尾添加元素，函数中的指针值未分配？ （使用代码：：块）

Question

I have been trying to implement function to add element at the end of an linked list but it is not working.

I tried to debug code in code::blocks and found that "h->next = newNode;" is not assigning the value.

#include <iostream>
using namespace std;

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

void printlist(Node* h){
    while(h->next!=nullptr){//or h!=0
        cout<<h->data<<endl;
        h = h->next;
    }
}

void pushend(Node* h, int newData){
    Node* newNode;
    newNode = new Node;
    newNode->data = newData;
    newNode->next = nullptr;
    while(h!=nullptr){
        if(h->next == nullptr){
            h->next = newNode;
            break;
        }
        h = h->next;
    }
}

int main(){
    Node* head;
    Node* second;
    Node* third;   
    head = new Node;
    second = new Node;
    third = new Node;  
    head->data = 1;
    head->next = second;  
    second->data = 2;
    second->next = third; 
    third->data = 3;
    third->next = nullptr;
    int newData = 4;
    pushend(head,newData);
    printlist(head);
}

Answer 1

I am not sure what you mean by h->next = newNode; is not assigning the value h->next = newNode; is not assigning the value .

I can see that you are making a list with {1, 2, 3} as data, and than adding a 4 to the end - and I can also see that your print only prints 1, 2, 3 . But that is not caused by an error in pushend . Instead it is because your printlist uses a while (h->next != nullptr) loop, which means that it will never print your last element (and that it will crash if you ever call it on an empty list ( h = nullptr )).

Change your printlist loop to while (h != nullptr) and all four elements will be printed.