复制链表堆栈类的构造方法：我的是向后复制

Question

So I've combed through what is already on this site about linked list stacks. Mine is a template class and I've also created a Node structure. From what I've seen with other questions, I understand that this isn't always the best considering standard library implementations already existing in C++ as mentioned in this first answer BUT this is for an assignment so it's all in the name of science.

This is the structure so you have an idea of what I've named things

template <class T>
struct Node
{ public:
  //data members
  T data;
  Node<T> *next;

  //methods
  Node(const T &);
};


template <class T>
Node<T>::Node(const T &newData)
{
data = newData;
next = NULL;
}

Nothing fancy. These are my Stack class's data members for reference

private:
  Node<T> *stkTop;  //or headPtr, so to speak
  int stkSize;

And this is my copy constructor as is

template <class T>
Stack<T>::Stack(const Stack<T> &existStack)
{

Node<T> *currentNode = existStack.stkTop;
stkSize = 0;
stkTop = NULL;

while( currentNode != NULL )
{
Node<T> *ptr = new Node<T>(0);

ptr -> data = (currentNode -> data);
ptr -> next = stkTop;
stkTop = ptr;

currentNode = currentNode -> next;

stkSize++;
}

So far so good... I'm even obeying the Rule of Three. I also have an overloaded assignment operator and a destructor (though to be honest the assignment operator is the same exact code, I've just included a test for self assignment).

I mean, it KIND OF works. All the values show up...just in reverse order... Totally stumped.

The implementing program I have just runs a couple short tests like explicitly calling the constructor, assigning a stack to another stack, assigning a stack to itself. Everything looks fine except for the order. I'm assuming I'm traversing my list wrong or something when copying values over....I don't know :(

Answer 1

You are going down (stack top to stack bottom) existStack with currentNode while you are going up this stack. The first item you inserted should have been the top, but instead the last node you inserted is the top.