Simple List implementation in C++. Just my first attempt. So far only works for int. That's fine ...

simpleList.cpp

#include <iostream>
using namespace std;

struct ListNode {
    int val;
    ListNode *next;
    ListNode ()
    {
        this->val = 0;
        this->next = 0;
    }
    ListNode (int *newval)
    {
        this->val = *newval;
        this->next = 0;
    }
};

struct List {

    List()
    {
        this->startNode = 0;
        this->endNode = 0;
        this->size = 0;
    }
    ~List()
    {        
        // there is at least one item
        if(startNode != 0)
        {   
            // release memory starting from the second item
            ListNode *current, *soon;
            current = this->startNode->next;
            while(current != 0)  // if there are at least two items
            {
                /* When there is no more items after current,
                 * delete current and leave.
                 * Otherwise, free up current and move on to
                 * the next item.
                 */
                if(current->next != 0)
                {
                    soon = current->next;
                    delete current;
                    current = soon;
                }
                else
                {
                    delete current;
                    break;
                }
                
            }
        }

        delete this->startNode;
        delete this->endNode;
    }

     /* Input: pointer of the item 
      * Output: Appends the item to the end of the list
      * With the help of endNode, we can efficently appends
      * the item to the end of the list. 
      */
    void add(int *val)
    {
        this->size += 1;
        ListNode *newNode = new ListNode(val);
        if (this->size == 1)
        {
           this->startNode = newNode;
           this->endNode = newNode;
        }
        else
        {
            this->endNode->next = newNode;
            this->endNode = newNode;
        }
        /*
        if (this->size == 1)
        {
            this->startNode = newNode;
        }
        else
        {
            ListNode *tmp = this->startNode;
            while (tmp->next)
                tmp = tmp->next;
            tmp->next = newNode;
            
        }
        */
    }

    int get_size()
    {
        return this->size;  
    }

    void print_all()
    {
        ListNode *tmp = this->startNode;
        for(size_t i = 1; i <= this->size; ++i)
        {
            cout << "item #" << i << " : val = " <<  tmp->val << endl;
            tmp = tmp->next;
        }
    }
private:
    ListNode *startNode;
    ListNode *endNode;
    size_t size;
};

int main()
{
    int *item, val = 1;
    item = &val;
    List myList = List();
    for (; val <= 10; ++val)
    {
        item = &val;
        myList.add(item);
    }
    cout << myList.get_size() << endl;
    cout << endl;
    myList.print_all();
    
    return 0;
}