Swap elements of adjacent nodes of the Linked List

/* C++ Program to swap elements of adjacent nodes of the linked list */
#include<bits/stdc++.h>
using namespace std;

/* Strcuture of the Node of the Linked List */
typedef struct node
{
    int data;
    struct node *next;
}Node;

/* Function to Insert Node at the end of the Linked List */
void insert_end(Node **head, int ele)
{
    /* Creating a new node */
    Node *new_node;
    new_node = (struct node*)malloc(sizeof(struct node));
    new_node->data = ele;
    new_node->next = NULL;
    
    /* check whether the linked list is empty or not */
    
    /* If Linked List is Empty, then new node will become head of the linked list */
    if(*head == NULL)     
    {
        *head = new_node;
        return;
    }
    
    /* If Linked List is not Empty, then traverse the complete linked list and point 
    the pointer of last node of the linked list to the new node of the linked list */
    Node *temp = NULL;
    temp = (*head);
    while(temp->next != NULL)
    temp=temp->next;
    temp->next = new_node;
}

/* Function to pairwise swap elements of a linked list */
void swapAdjacent(Node *head)
{
    /* If Linked List is empty or contains only one node, then return. */
    if(head == NULL || head->next == NULL)
    return;
    
    /* If Linked List contains more than one nodes, then traverse the 
       linked list and swap each node’s data with the next node’s data, if exist.
    */
    Node *temp = head;
    while(temp && temp->next)
    {
        int temp_var = temp->data;
        temp->data = temp->next->data;
        temp->next->data = temp_var;
        
        temp = temp -> next -> next;
    }    
}

/* Function to Print the Linked List */
void print(Node *head)
{
    Node *temp = head;
    while(temp!=NULL)
    {
        cout<<temp->data<<" ";
        temp=temp->next;
    }
    cout<<endl;
}
int main()
{
    Node *head = NULL;
    /* Inserting Some Nodes in the Linked List */
    insert_end(&head,12);
    insert_end(&head,34);
    insert_end(&head,88);
    insert_end(&head,56);
    insert_end(&head,66);
    insert_end(&head,78);
    cout<<"Printing the Linked List before Swapping:\n";
    print(head);
    
    /* swap adjacent node data */
    swapAdjacent(head);
    
    cout<<"\nPrinting the Linked List after Swapping:\n";
    print(head);
    
}