trl-lib/stack-llama · How to implement a linked list in C++?

Question:

How to implement a linked list in C++?

Answer:

There are a few implementations of linked lists on the internet, most of which are rather outdated. Here’s one that’s not too bad.

Here’s a fairly straightforward implementation of a doubly-linked list in C++:

#include <iostream>
#include <string>
#include <cstdlib>
#include <cstddef>
#include <cstdint>
#include <list>
#include <vector>

struct ListNode {
    int data;
    struct ListNode *next;
    struct ListNode *prev;
};
ListNode *createListNode(int data) {
    ListNode *newNode = new ListNode();
    newNode->data = data;
    newNode->next = NULL;
    newNode->prev = NULL;
    return newNode;
}
ListNode *createListNode(int data, int left, int right) {
    ListNode *newNode = createListNode(data);
    newNode->next = createListNode(left);
if(left!= right)
    newNode-&gt;next-&gt;prev = newNode;
else
    newNode-&gt;next = createListNode(right);
newNode-&gt;next-&gt;prev = newNode;
return newNode;

}
void printListNode(ListNode *node) {
    if(node)
        std::cout << node->data << " -> ";
    else
        std::cout << "NULL";
}
void printList(ListNode *node) {
    while(node)
        printListNode(node);
}
void printList(ListNode *node) {
    printList(node->next);
    printListNode(node);
    printList(node->prev);
}
void printList(ListNode *node) {
    if(node)
        printList(node->next);
    else
        std::cout << "NULL";
}
int main() {
    ListNode *head = createListNode(1);
    head = createListNode(2, head);
    head = createListNode(3, head);