implementing doubly linked list in C++

I have a trouble implementing doubly linked list especially in a function that swap the adjacent elements.

Here is my original code:

#include<iostream>
using namespace std;

struct node {
    int data; 
    node *prev;
    node *next;
};
node *head = NULL;

node* getNewNode (int i){
    node *newNode = new node; //allocate a dynamic memory in the heap
    newNode->data = i;
    newNode->prev = NULL;
    newNode->next = NULL;
    return newNode;
}


void InsertAtHead(int i){
    node *newNode = getNewNode(i);
    if (head == NULL){   //addressing inserting the first node in the list.
        head =  newNode;
        return;
    }
    
    newNode->next = head;
    head->prev = newNode;
    head = newNode;
    
    }
void swapAdjacent() {
    node *temp = head;
    while (temp != NULL ) {
        node *temp1 = temp;
        node *temp2 = temp->next;
        temp1->next = temp2->next;
        temp2->prev = temp1->prev;
        if (temp1->prev != NULL) {
            temp1->prev->next = temp2;
        }
        temp1->prev = temp2;
        temp2->next = temp1;
       
        if (temp == head) {
            head = temp2;
        }
        temp = temp->next->next;
    }
}





void display (){
    node *temp = head;
    while (temp != NULL){
        cout  <<temp->data << '\t';
        temp = temp->next;
    
    }
    cout << '\n';
}



int main (){
    InsertAtHead(8); 
    InsertAtHead(4);
    InsertAtHead(12);
    InsertAtHead(3);
    InsertAtHead(-8);
    InsertAtHead(7);
    cout << "The original list is: " << endl;
    display();
    swapAdjacent();
    cout << "The list after swapping the adjacent elements is: " << endl;
    display();
    
   
    return 0;
}

The original list is The original list is: 7 -8 3 12 4 8 The output I got after calling swapAdjacent() is : -8 7 3 4 12 8 while I am looking for: -8 7 12 3 8 4

I tried visualizing this with pen and paper, did several attempts to look it up and even I used chat GPT to no avail. I always don't get the output I am looking for.

I appreciate all of your feedback.