c++ - 如何解决代码中的错误并解释错误消息

Question

所以我正在做一个使用链表的项目。该程序基本上是输入数字，直到输入-999，然后对其进行操作。我遇到问题的两个操作是 deleteAll（从列表中删除所有相同的值）和 deleteSmallest（删除列表中的最小值）。调用这两个函数的代码如下：

    int num;
    cout << "Enter a number you would like deleted from the whole list: ";
    cin >> num;

    uList.deleteAll(num);
    cout << "New list: " << uList << endl;

    uList.deleteSmallest();
    cout << "After deleting the smallest number, the list now is: " << uList << endl;

deleteAll 的代码如下：

    template <class Type>
    void UnorderedLinkedList<Type>::deleteAll(const Type& deleteItem)
    {
        NodeType<Type>* curr;
        NodeType<Type>* p = NULL;
        NodeType<Type>* q = NULL;

        curr = first;

        if(first == NULL)
            throw std::runtime_error("Cannot delete from an empty list");
        else
        {
            for(int i = 0; i < count; i++)
            {
                if(curr->info == deleteItem)
                {
                    p = curr;
                    q = p->link;
                    p->link = q->link;
                    delete q;
                }
                curr = curr->link;
            }
        }
        delete p;
        delete curr;
    }

deleteSmallest 的代码如下：

    template <class Type>
    void UnorderedLinkedList<Type>::deleteSmallest()
    {
        NodeType<Type>* curr;
        NodeType<Type>* p;
        NodeType<Type>* q;
        NodeType<Type>* r;

        curr = first;

        if (first == NULL)
            throw std::runtime_error("Cannot delete from an empty list");
        else
        {
            for(int i = 0; i < count; i++)
            {
                if(curr->link->info < curr->info)
                {
                    int smallest = curr->link->info;
                    p = curr;
                    q = curr->link;
                }
                curr = curr->link;
            }
        }
        r = q->link;
        p->link = q->link;
        delete q;
    }

我得到的错误是：

    1 [main] Project 5 4044 cygwin_exception::open_stackdumpfile: Dumping stack trace to Project 5.exe.stackdump

很抱歉发布一个大问题，但是有人可以解释在这种情况下错误意味着什么以及我正在做什么导致这种情况出现？谢谢！

Answer 1

因为deleteAll()你应该做这样的事情：

else
{
    for (Node* prev = curr; curr != NULL; prev = curr, curr = curr->link)
    {
        if (curr->info == deleteItem)
        {
            NodeType<Type>* temp = curr;
            curr = curr->link;

            if (prev)
                prev->next = curr;
            delete temp;
        }
    }
}

你以前的方式根本没有删除curr。您还应该删除底部的delete p和，因为它们是多余的。delete curr

对于deleteSmallest()，您需要保持一个指向最小节点的指针（以及指向它之前的前一个节点），因此当循环完成时，您知道删除了什么：

else
{
    Node* prev = NULL, **smallest;

    for (Node** curr = smallest = head, *back(*head); *curr != NULL; back = *curr, curr = &(*curr)->link)
    {
        if ((*curr)->info < (*smallest)->info)
        {
            prev = back;
            smallest = curr;
        }
    }

    Node* temp = *smallest;
    *smallest = (*smallest)->link;

    if (prev)
        prev->link = *smallest;
    delete temp;
}