C ++析构函数按值删除指针函数

Question

我有此代码：

class allShapes {
private:
    Shape ** _arr;
    int _size;
public:
    allShapes();
    ~allShapes();
    int getSize() const;
    void addShape(Shape * newShape);
    allShapes operator+(const allShapes & other) const;
}

allShapes::~allShapes()
{
    if (_arr != NULL)
    {
        for (int i = 0; i < getSize(); i++)
        {
            delete _arr[i];
            _arr[i] = NULL;
        }

        delete[] _arr;
        _arr = NULL;
    }
};


allShapes allShapes::operator+(const allShapes & other) const
{
    allShapes newallShapes;
    for (int i = 0; i < getSize(); i++)
    {
        newallShapes.addShape(_arr[i]);
    }

    for (int i = 0; i < other.getSize(); i++)
    {
        newallShapes.addShape(other._arr[i]);
    }

    return newallShapes;
}

我的主：

allShapes shapes;

Circle * c1 = new Circle(3, "myCircle");
Circle * c2 = new Circle(2, "yourCircle");

shapes.addShape(c1);
shapes.addShape(c2);

allShapes newshape = shapes + shapes;

---

我的项目有问题：

有一些背景知识：我有allShapes，其中包含其他一些类，例如Circle和Square等。

我的操作员+有问题，

它将在方法中创建newallShapes良好，但随后在最后一行中：return newallShapes; 它调用析构函数，然后删除指针 newall形状并破坏一切！

我如何将带有所有指针的新“ newallShape”发回主机？