public void Insert(T elt)
        {
            if (nbElements >= array.GetLength(0))
            {
                T[] newArray = new T[array.GetLength(0) * 2];
                for (int i = 0; i < array.GetLength(0); i++)
                {
                    newArray[i] = array[i];
                }
                array = newArray;
            }

            array[nbElements] = elt;
            nbElements++;
        }

        public T At(int i)
        {
            if (i > -1 && i < nbElements)
                return array[i];
            else
                throw new Exception("Index error");
        }