如何使用 c++ 中的 NEW 运算符为完整列表分配更多内存？

问：

我正在尝试制作带有歌曲的播放列表。我在 c++ 中使用 List 数据结构。我想改进函数 insert（），如果我的列表充满了 100 首歌曲，我可以使用运算符 NEW 为列表分配更多内存。我还必须使用 delete[] 解除分配现有内存。

我不确定如何创建一个新列表并将它们连接在一起。

这是我的 List 类：

#include <string>
#include <iostream>
#include <stdexcept>
using namespace std;


template<class ItemType>
class List
{
private:
    static const int CHUNK_SIZE=100;
    ItemType *list;
    int numItems;
    int maxItems;
public:
    // default constructor and destructor
    List()
    {
      numItems = 0;
      maxItems = CHUNK_SIZE;
      list = new ItemType[CHUNK_SIZE];
    }

    ~List()
    {
      delete[] list;
    }
    
    // list member functions
    bool isEmpty()  const 
    {
      return numItems==0;
    }


    int getLength() const 
    { 
      return numItems; 
    }
    bool insert(int pos, const ItemType& item);

    bool remove(int pos);
    
    // clear the list
    // clear can simply set numItems to zero.  The array list may still contain
    // items already inserted into the list, but since numItems is zero, there
    // isn't any way to get at them using getEntry() or setEntry()
    void clear()
    {
      numItems = 0;
    }
    
    // return entry at postion pos
    // throw invalid_argument if pos<1 or pos>getLength()
    ItemType getEntry(int pos) const;
    
    // set entry at postion pos to item
    // throw invalid_argument if pos<1 or pos>getLength()
    // changes whatever is inside the position to that item. swap. 
    void setEntry(int pos, const ItemType& item);
    
};

这是我的 insert（） 函数：

template<class ItemType>
bool List<ItemType>::insert(int pos, const ItemType& item)
{
    bool canAdd;
    
    canAdd = ((pos > 0) && (pos <= numItems + 1) && (numItems < maxItems));
    if (canAdd)
    {
        // first, we have to move everything after our insertion point over one
        // position to make room for our new item.  start at the back of the list.
        // don't forget arrays start at postion zero and our list ADT starts at
        // position 1.
        for(int i=numItems; i>=pos; i--)
            list[i] = list[i-1];
        
        // now put our item at position pos-1
        list[pos-1] = item;
        
        numItems++;
    }

    return canAdd;
}

这是我的 main（） 函数：

int main()
{
    List<string> songs;
    char goAgain = 'y';
    int trackNumber;
    string trackName;
    
    // Insert some songs into our list

    songs.insert(1, "Bohemian Rhaspody");

    songs.insert(2, "The Highway Song");

    songs.insert(3, "In the Loop");

    songs.insert(4, "Lovesong");

    songs.insert(5, "Blow The Whistle");

    songs.remove(1);
      
    cout << "Welcome!  There are " << songs.getLength() << " tracks.\n";
    while (goAgain!='n')
    {
        trackNumber = getTrack();
        try
        {
            trackName = songs.getEntry(trackNumber);
        }
        catch (invalid_argument arg)
        {
            cout << arg.what() << endl;
            trackName = "No Track";
        }
        cout << "Your track name is " << trackName << endl;
        cout << "Go again? (y/n) ";
        cin >> goAgain;
    }
    
    cout << "you're ready to rock!\n";
    return 0;
}