itemsCount

public class Inventory
    {
        string[] arrayItems = new string[6];
        int itemsCount = 0;
        public void AddItem(string item)
        {
            if (itemsCount >= 6)
            {
                Console.WriteLine("Inventory full");
            }
            else
            {
                arrayItems[Array.IndexOf(arrayItems, null)] = item;
                itemsCount++;
                Console.WriteLine("{0} has been added to your inventory. Number of items:{1}", item, itemsCount);
            }
        }