C++ program to reverse a linked list by changing links between nodes

Run

#include<iostream>
using namespace std;

struct node
{
    int num;
    node* nextptr;
} * stnode; //node constructed

void createList(int n);
void reverse(node** stnode);
void displayList();

int main()
{
    int n, num, item;

    cout << "Enter the number of nodes: "; cin >> n;
    createList(n);

    cout << "\nLinked list data: \n";
    displayList();

    cout << "\nAfter reversing\n";
    reverse(&stnode);

    displayList();

    return 0;
}

void createList(int n)
{
    struct node* frntNode, * tmp;
    int num, i;

    stnode = new node();
    if (stnode == NULL)
    {
        cout << "Memory can not be allocated";
    }
    else
    {
        cout << "Enter the data for node 1: "; cin >> num;
        stnode->num = num;
        stnode->nextptr = nullptr; // Links the address field to NULL
        tmp = stnode;

        for (i = 2; i <= n; i++)
        {
            frntNode = new node();

            if (frntNode == nullptr)
            {
                cout << "Memory can not be allocated";
                break;
            }
            else
            {
                cout << "Enter the data for node " << i << ": "; cin >> num;
                frntNode->num = num;
                frntNode->nextptr = nullptr;
                tmp->nextptr = frntNode;
                tmp = tmp->nextptr;
            }
        }
    }
}

void reverse(node** stnode)
{
    node* temp = nullptr;
    node* prev = nullptr;
    node* current = (*stnode);

    while (current != nullptr)
    {
        temp = current->nextptr;
        current->nextptr = prev;
        prev = current;
        current = temp;
    }
    (*stnode) = prev;
}

void displayList()
{
    struct node* tmp;
    if (stnode == nullptr)
    {
        cout << "List is empty";
    }
    else
    {
        tmp = stnode;
        while (tmp != nullptr)
        {
            cout << tmp->num << "\t"; tmp = tmp->nextptr;
        }
    }
}