Custom implementation of doubly linked list not working (educational) - c++

Question

I implemented my own simple version of a doubly linked list. Unfortunately, there seems to be an error with it. The head of the list seems to move to the new Node, each time I add one with push_back. Because of this, print will print the last value indefinitely.
Linked List:
struct doubly_linked_list
{
Node *head = nullptr;
Node *tail = nullptr;
void push_back(Node n)
{
if (this->head == nullptr)
{
this->head = &n;
this->tail = nullptr;
}
n.prev = this->tail;
if (this->tail)
{
n.prev->next = &n;
}
this->tail = &n;
}
void print()
{
Node *tmp = this->head;
while (tmp != nullptr)
{
std::cout << tmp->data << ", ";
tmp = tmp->next;
}
}
};
Where Node is implemented as
struct Node
{
int data;
Node *next = nullptr;
Node *prev = nullptr;
Node(int data)
{
this->data = data;
}
Node()
{
this->data = -1;
}
};
main
int main()
{
doubly_linked_list dl;
dl.push_back(Node{3});
dl.push_back(Node{2});
dl.push_back(Node{1});
dl.push_back(Node{0});
dl.push_back(Node{5});
dl.print(); // print 5 forever
}
Disclaimer: Pls be aware that the topic of this post is educational. I know about the lists in the c++ standard.

Answer 1

Here is a working example with raw pointers, deppending on what you are doing you might want to change that to smart pointers.
#include <iostream>
struct Node
{
int data;
Node *next = nullptr;
Node *prev = nullptr;
Node(int data)
{
this->data = data;
}
Node()
{
this->data = -1;
}
};
struct doubly_linked_list
{
Node *head = nullptr;
Node *tail = nullptr;
void push_back(Node* n)
{
if (this->head == nullptr)
{
this->head = n;
this->tail = nullptr;
}
n->prev = this->tail;
if (this->tail)
{
n->prev->next = n;
}
this->tail = n;
}
void print()
{
Node *tmp = this->head;
while (tmp != nullptr)
{
std::cout << tmp->data << ", ";
tmp = tmp->next;
}
}
};
int main()
{
doubly_linked_list dl;
dl.push_back(new Node{3});
dl.push_back(new Node{2});
dl.push_back(new Node{1});
dl.push_back(new Node{0});
dl.push_back(new Node{5});
dl.print(); // print 5 forever
}