Stack Implementation with Linked Lists

// Stack implementation using Linked Lists
#include <iostream>

using namespace std;

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

struct node *top = NULL, *temp;

int main() {
    int choice, data;

    // infinite loop is used to insert/delete infinite number of nodes
    while(true) {
        cout << "\n1. Push\n2. Pop\n3. Display\n4. Exit\n";
        cout << "\nEnter ur choice: ";
        cin >> choice;

        switch(choice) {
            case 1: // push - add an item to the stack
                temp = new node;
                //temp = (struct node *)malloc(sizeof(struct node));
                cout << "\nEnter a node data: ";
                cin >> data;
                temp->data = data;
                temp->link = top;
                top = temp;
            break;
            case 2: // pop - print an item from the stack ad delete it
                if(top != NULL) {
                    cout << "\nThe poped element is:  " << top->data;
                    top = top->link;
                } else {
                    cout << "\nStack Underflow";
                }
            break;
            case 3: // print all elements of the stack (without deletion)
                temp = top;
                if(temp == NULL) {
                    cout << "\nStack is empty\n";
                }

                while(temp != NULL) {
                    cout << " -> " << temp->data;
                    temp = temp->link;
                }
            break;
            case 4: // goes out from infinite loop and terminate the execution
                return 0;
        }
    }
}