Why C++ act differently from debuging?

See more:

C++

I was implemeting LinkedList in c++.

I was expecting :

List is not empty!!
4	

But result was :

List is not empty!!
5	

and Funny how that when I debug and so 'Step over' and over again, I got the expected result. Is there anyone who tells me that I'm missing something?

#include <iostream>
using namespace std;

struct node {
    int data;
    node *next;
};

class LinkedList {
    node *head;
    node *tail;
    
public:
    LinkedList(){
        head = nullptr;
        tail = nullptr;
    };
    
    void createNode(int value);
    void display();
};

void LinkedList::createNode(int value){
    node *temp = new node;
    temp->data = value;
    temp->next = nullptr;
    
    if(head == nullptr){
        head = temp;
        delete temp;
        temp = nullptr;
    } else {
        cout << "List is not empty!!" << endl;
    }
};

void LinkedList::display() {
    node *displayNode = new node;
    displayNode = head;
    while(displayNode != nullptr)
    {
        cout<<displayNode->data<<"\t";
        displayNode=displayNode->next;
    }
}

int main(){
    LinkedList *list1 = new LinkedList();
    list1->createNode(4);
    list1->createNode(5);
    
    list1->display();
};

What I have tried:

I have tried compile and debugging.