when I execute linked list using class it shows an extra zero

Question

#include<bits/stdc++.h>
#include<vector>
using namespace std;
class Node {
    public :
    int data;
    Node *next;

    Node()
    {
        data = 0;
        next = NULL;
    }
    Node (int a)
    {   data = a;
        next = NULL;
    }
};
void push(Node **head_ref , int n)
{  
    Node *new_node = new Node();
    new_node -> data = n;
    new_node -> next = *head_ref;
    *head_ref = new_node;}

void display(Node *head_ref)
{ while(head_ref != NULL)
    {
        cout << head_ref -> data << " ";
        head_ref = head_ref-> next;
    }
}
int main()
{   Node *head = new Node();
    push (&head  ,1 );
    push(&head ,0 );
    push(&head , 1);
    display(head);
    return(9);}

This when executed returns 1 0 1 0 as output , First i thought it is because of constructors but later I came to know that it is not something causing the problem.

Answer 1

Node *head = new Node();

Creates the extra node. Instead use

Node *head = nullptr;

or, if using an older compiler,

Node *head = NULL;

to point head at a safe location until legitimate nodes are added.