code got strucked in a infinite loop when I tried to reverse a linked list using recursion

Question

I was trying to reverse a linked list using recursion but when I tried to print out all the elements of the linked list at first it was printing out elements as expected but after printing out the last element it started printing the last and second last element repeatedly. I tried to debug it and I think the problem is that the last element is pointing towards the second last element whether it should be pointing towards NULL. I am not able to figure out what is wrong with my code so please help me out.

example- input 1,2,3,4,5,6

expected output 6,5,4,3,2,1

actual output 6,5,4,3,2,1,2,1,2 ...

#include<iostream>
        
using namespace std;
class node{

public:
int val;
node *next;
node(int val)
{
  this->val = val;
  this->next = NULL; 
}
node(int val,node *next)
{
  this->val= val;
  this->next=next;
}

};

void insertAtTail(node *&head,int val){
  
  node *n = new node(val);
  if (head==NULL)
  {
    head = n;
    return;
  }
  node *temp = head;
  while (temp->next!=NULL)
  {
    temp = temp->next;
  }
  temp->next=n;

}
void display(node *head)
{
  node *n = head;
  while (n!=NULL)
  {
    cout << n->val << "->";
    n = n->next;
  }
  cout << "NULL" << endl;
  
}
node* reverseRecursive(node *&head)
{
  if (head == NULL || head->next==NULL)
  {
    return head;
  }
  node *nHead = reverseRecursive(head->next);
  head->next->next = head;
  head->next == NULL;
  return nHead; //  1->2->3->4->5->6->NULL  
}

int main()
{

node *head = NULL;
insertAtTail(head,1);
insertAtTail(head,2);
insertAtTail(head,3);
insertAtTail(head,4);
insertAtTail(head,5);
insertAtTail(head,6);
display(head);
node *newhead = reverseRecursive(head);
display(newhead);
return 0;
}

Answer 1

There is a bug in function reverseRecursive().

Line head->next == NULL; should be head->next = NULL;

node* reverseRecursive(node *&head)
{
  if (head == NULL || head->next==NULL)
  {
    return head;
  }
  node *nHead = reverseRecursive(head->next);
  head->next->next = head;
  head->next == NULL;                       // <<< should be  head->next = NULL;
  return nHead; //  1->2->3->4->5->6->NULL  
}

Not sure which compiler you were using, but this statement will typically generate a warning.