以棧為例，之前是增加一個元素就要重新new一個比原來大1的陣列出來替換原始陣列。

public void Push(T item)
{
    int size = Size();
    T[] newarray = new T[size + 1];
    for (int i = 0; i < size; i++)
    {
        newarray[i] = array[i];
    }
    newarray[size] = item;
    this.array = newarray;
}

將stack類進行修改優化，減少了重複定義的次數，提高了入棧出棧效率

public class My_Stack<T>
{
    public My_Stack()
    {
        Max_Capacity = 8;
        array = new T[Max_Capacity];
        actual_size = 0;
    }
    private T[] array;
    private int Max_Capacity;
    private int actual_size;
    /// <summary>
    /// 入棧
    /// </summary>
    /// <param name="item"></param>
 

    public void Push(T item)
    {
        if (actual_size > Max_Capacity / 2) 
        {
            //翻倍
            Max_Capacity *= 2;
            T[] newarray = new T[Max_Capacity];
            for (int i = 0; i < actual_size; i++)
            {
                newarray[i] = array[i];
            }
 

            newarray[actual_size] = item;
            this.array = newarray;
        }
        else
        {
            array[actual_size] = item;
        }
        actual_size += 1;
    }
    /// <summary>
    /// 出棧
    /// </summary>
    /// <param name="item"></param>
    public T Back()
    {
        if (Size() == 0)
        {
            Console.WriteLine("未新增元素");
            return default(T);
        }
        else
        {
            T num = array[actual_size - 1];
            array[actual_size - 1] = default(T);
            actual_size -= 1;
            return num;
        }
    }
    /// <summary>
    /// 刪除後進的一個元素
    /// </summary>
    public void Pop()
    {
        if (Size() == 0)
        {
            Console.WriteLine("未新增元素");
        }
        else
        {
            array[actual_size - 1] = default(T);
            actual_size -= 1;
        }
    }
    /// <summary>
    /// 判斷是否為空
    /// </summary>
    /// <returns></returns>
    public bool Isempty()
    {
        if (actual_size == 0)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    /// <summary>
    /// 獲取大小的方法
    /// </summary>
    /// <returns></returns>
    public int Size()
    {
        if (array == null)
        {
            return 0;
        }
        else
        {
            return actual_size;
        }
    }
    /// <summary>
    /// 獲取佇列長度的屬性
    /// </summary>
    public int Length
    {
        get
        {
            return Size();
        }
    }
    /// <summary>
    /// 理論最大容量
    /// </summary>
    public int MaxCapacity
    {
        get
        {
            return Max_Capacity;
        }
    }
}