C++ vector 问题

Question

我正在使用 std::vector 来保存一些具有动态分配成员的对象，当我将事物放入 vector 时，发生了一些我不理解的事情。

1. 我调用了 push_back() 并使用对象的构造函数作为参数，但出于某种原因它转到了对象的析构函数。为什么是这样;应该是加而不是删？

2. 我第二次调用 push_back() 执行与之前相同的操作，但这次它在 dbgdel.cpp operator delete (第 52 行)。但永远不应在构造函数或 push_back() 中调用 delete。

我不确定哪些代码部分与这个问题相关，因为有问题的行在方法中非常根深蒂固。

编辑:添加代码

class Thing{
    int** Array;
    int size;   // of square array
    Point current; // location
    Thing(int _n){
        // allocates, and gives values to the array, and members
        // only constructor
    }
};
class ThingMgr{
    Thing * Control;
    Thing * Current;
    Thing * Previous;
    int size;  // size of all. same use as in Thing
    ThingMgr(int _n){
        size = _n;
        Control = new Thing(size);
        Current = new Thing(size);
        Previous = new Thing(size);
    }
    void rearrange(int _num){
        std::vector<Thing> possibles;

        // performs deterministic work on members

        // [0] first
        possibles.push_back(Thing(size)); // this succeeds
        // [1] second
        possibles.push_back(Thing(size)); // this fails

        // more operations to be performed never reached.
    }
};

Answer 1

first: I call push_back() and use the constructor of the objects as the argument, but for some reason it goes to the destructor of the object. why is this; it should be adding not deleting?

您正在将该元素的拷贝 推送到vector 中。您构建一个时间元素，调用其复制构造函数以在 vector 中创建一个拷贝，然后调用时间元素的析构函数。

second: I call push_back() a second time doing the same as before, but this time it throws an illegal memory access at dbgdel.cpp operator delete (line 52). but delete should never be called in a constructor, or push_back().

奇怪的是，第二次调用时会发生这种情况，但最终当 vector 需要重新生长时，它会再次复制元素。

您可能没有为相关元素提供适当的复制构造函数。