Quiz Add Function

DList::DList()
{
    item_list = NULL;
    item_amounts = NULL;
    num_items = 0;
}

DList::DList(string item, int amount)
{
    //Check to see if Lists are empty
    if (num_items < 0)
    {
        item_list = new item_list[num_items+1];
        item_amounts = new item_amounts[num_items+1];
        item_list[num_items] = item;
        item_amounts[num_items] = amount;
    }
    //if list is not empty
    else
    {
        //Create 2 temporary arrays to store previous values
        string *tempa = new tempa[num_items+1];
        int *tempb = new tempb[num_items+1];

        /*Cycle through existing arrays to copy values and leave
        one empty cell at the end of each temp array*/
        for (int i =0; i < num_items; i++)
        {
            tempa[i] = item_list[i];
            tempb[i] = item_amounts[i];
        }

        //Assign given values to last cell in temp arrays
        tempa[num_items+1] = item;
        tempb[num_items+1] = amount;

        //Deletes old arrays to create bigger ones
        delete[] item_list;
        delete[] item_amounts;

        //Create new 1-cell-larger arrays
        item_list = new item_list[num_items+1];
        item_amounts = new item_amounts[num_items+1];

        //Copy temp values to new larger arrays
        for (int i =0; i < num_items+1; i++)
        {
            item_list[i] = tempa[i];
            item_amounts[i] = tempb[i];
        }

        //Deletes temporary arrays
        delete[] tempa;
        delete[] tempb;

        //Sets Number of items to +1
        num_items++;
    }
}