LINKED LISTS

#include<iostream>

using namespace std;

struct node{
	int number;
	node *next;
};
bool isempty(node *head){
	if(head == NULL){
		return true;
	} else {
		return false;
	}
}
int menu(){
	int choice;
	cout << "Menu : \n";
	cout << "1: Insert a number to the list \n";
	cout << "2: Remove a number from the list \n";
	cout << "3: Show List\n";
	cout << "4: Exit \n";
	cin >> choice;
	return choice;
}
void insertasfirst(node *&head, node *&last, int number){
	node *temp = new node;
	temp->number = number;
	temp->next = NULL;
	head = temp;
	last = temp;
}
void insert(node *&head, node *&last, int number){
	if(isempty(head)){
		insertasfirst(head, last, number);
	} else {
		node *temp = new node;
		temp->number = number;
		temp->next = NULL;
		last->next = temp;
		last = temp;

	}
}
void remove(node *&head, node *&last){
	if(isempty(head)){
		cout << "List is empty.\n";
	} else if(head == last){
		delete head;
		head == NULL;
		last == NULL;
	} else {
		node *temp = head;
		head = head->next;
		delete temp;
	}
}
void showlist(node *current){
	if(isempty(current)){
		cout << "List is empty.\n";
	} else {
		cout << "The list contains : \n";
		while(current != NULL){
			cout << current->number << endl;
			current = current->next;
		}
	}
}
int main() {
	node *head = NULL;
	node *last = NULL;
	int choice;
	int number;
	do{
		choice = menu();
		switch(choice){
			case 1:
				cout << "Enter a number: ";
				cin >> number;
				insert(head, last, number);
				break;
			case 2:
				remove(head, last);
				break;
			case 3:
				showlist(head);
				break;
			default:
				cout << "Program ends. \nGood Bye!";
		}
	} while(choice != 4);
	return 0;
}