Linked List Implementation in C++

Linked List.cpp

// Linked List CPP
#include<iostream>

using namespace std;

class Node
{
public:
    int data;
    Node *next;
};

class List
{
    Node *head;
    Node *tail;
    Node *temp;
    bool isEmpty()
    {
        return head == NULL;
    }
public:
    List()
    {
        head = NULL;
        tail = NULL;
    }

    void insert(int x)
    {
        temp = new Node;
        temp->data = x;
        if(isEmpty())
        {
            temp->next = NULL;
            tail = temp;
        }
        else
            temp->next = head;
        head = temp;
    }

    void insertAtEnd(int x)
    {
        temp = new Node;
        temp->data = x;
        temp->next = NULL;
        if(isEmpty())
        {
            head = temp;
            tail = temp;
        }
        else
        {
            tail->next = temp;
            tail = temp;
        }
    }

    void remove(int x)
    {
        temp = head;
        Node *prev;
        while(temp->next != NULL && temp->data != x)
        {
            prev = temp;
            temp = temp->next;
        }
        if(temp->data == x)
        {
            prev->next = temp->next;
            delete temp;
        }
        else if(temp->next == NULL)
        {
            cout << "Error: Number Not found..." << endl;
        }
    }

    void find(int x)
    {
        int i;
        for(i=1, temp = head;temp->next != NULL && temp->data != x;temp = temp->next, i++);
        if(temp->data == x)
        {
            cout << "Found at position:" << i << endl;
        }
        else if(temp->next == NULL)
        {
            cout << "Error: Number Not found..." << endl;
        }
    }

    void display()
    {
        if(!isEmpty())
        {
            for(temp = head; temp != NULL; temp=temp->next)
                cout << temp->data << " ";
            cout << endl;
        }
        else
        {
            cout << "List is Empty!" << endl;
        }
    }
};

int main()
{
    List l;
    l.display();
    l.insert(15);
    l.display();
    l.insert(25);
    l.display();
    l.insert(35);
    l.display();
    l.insert(45);
    l.display();
    l.find(15);
    l.remove(25);
    l.display();
    l.insertAtEnd(55);
    l.insertAtEnd(65);
    l.display();
}

Where is destructor?

I noticed a few issues with the remove method in this implementation:

1. Removing the first element in the list does not properly set the head pointer to the next element.
2. Removing the last element in the list does not properly set the tail pointer to the second to last element.
3. The pointers head/tail are not set to NULL if we remove all of the elements.

Basically there are some edge cases unaccounted for as well as cleanup due to removing first/last elements. Otherwise, thanks for the gist!

It's better to set your pointers to nullptr rather than NULL.