为什么每次我尝试更改对象时我的复制构造函数都会产生段错误答案

【问题标题】：why is my copy constructor producing a segfault everytime i try to alter the object为什么每次我尝试更改对象时我的复制构造函数都会产生段错误
【发布时间】：2013-02-26 13:01:04
【问题描述】：

/* Copy constructor */
List(const List<value_type>& list)
{
    // for (iterator it = list.begin(); it != list.end(); ++it); 
    //   this->push_back(*it);
    // The commented part above is what I want it to do.
    std::cout << "empty = " << this->empty(); // no seg fault;
    std::cout << "size = " << this->size(); // also causes a seg fault
    this->push_back("string") // causes a seg fault
}

尝试运行此代码会使我的程序出现段错误。似乎每次我尝试更改或更改（this）时，它都会抛出一个段错误。

它还说 (this) 不是空的（这似乎是唯一一个不抛出 seg 错误的）

这里是调用更多信息的方法的代码。希望这里的人能给我一些关于这里发生的事情的见解。

void insert(iterator position, const value_type& in)
{
    // If inserting at the front, just change the head to a new Node
    if (position == this->head) 
        this->head = new Node<value_type>(in);
    else
    {
        Node<value_type>* node = this->head;
        // iterate to the position of "position".
        for (; node->next != position.node; node = node->next);
        node->next = new Node<value_type>(in);
    }
    // This is here to put back all the old data into it's correct position.
    // I was having way too much with keeping the integrity of the data
    // while inserting into the middle of the list, so I created this little hack.
    for (iterator it = position; it != this->end(); ++it)
    {
            Node<value_type> *node = this->head;
            for (; node->next != NULL; node = node->next);
            node->next = new Node<value_type>(it.node->data);
    }
}

// Insert at end
void push_back(value_type in)
{
    this->insert(this->end(), in);
}

unsigned size()
{
    if (this->empty()) return 0;
    unsigned i = 0;
    for (iterator it = this->begin(); it != this->end(); ++it, ++i);
    return i;
}

bool empty() const { return this->head == NULL; }

【问题讨论】：

标签： c++ list segmentation-fault containers copy-constructor

【解决方案1】：

在我写完这篇文章后几乎立即就解决了问题。

我所要做的就是首先将 head 分配给 NULL

List(List<value_type>& list)
{
    this->head = NULL;

    for (iterator it = list.begin(); it != list.end(); ++it)
        this->push_back(*it);
}

【讨论】：