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我正在尝试为模板化的双链表编写一个复制构造函数......这是我到目前为止所拥有的：

// Copy Constructor
template <typename Item>
LinkedList<Item>::LinkedList(const LinkedList<Item> &s){
    // Create an iterator for the other list
    ListNode<Item> *node = s.head;
    // Create a reference to use as an iterator for the new list
    // Set it to the address of head of the new list
    ListNode<Item> **curr_node = &head;
    // Create a placeholder for the address of the previous node
    ListNode<Item> *prev_node = NULL;
    while(node != NULL){
            *curr_node = new ListNode<Item>;
            // If a prev_node address has been saved, initialize the new node's prev value
            // If a prev_node hasn't been saved yet, this means it is the head and prev should
            // be initialized to NULL 
            (*curr_node)->prev = prev_node;
            // Set the new node data fields to that of the node in the other list
            (*curr_node)->data = node->data;

            // -------- Set up for next iteration ------- 
            // Save the address of the current node to be used in the next node's prev_node 
            prev_node = *curr_node;
            // Set the curr_node pointer to the address of the next node in the new list 
            curr_node = &((*curr_node)->next);
            // Set the node pointer to the next node in other list
            node = node->next;
    }
    // Set the tail after all the nodes have been copied
    tail = prev_node;
}

当我在测试仪中调用此代码时：

LinkedList<int> ll;
ll.insert_back(5); 
ll.insert_back(10);
ll.insert_back(15);
LinkedList<int> ll1 = ll;
cout << "Printing contents of copied list: "; ll1.print();

我在 valgrind 中收到此错误：

Contents of list to be copied: [5] -> [10] -> [15]
==4624== Conditional jump or move depends on uninitialised value(s)
==4624==    at 0x401077: LinkedList<int>::print() (LinkedList.cc:159)
==4624==    by 0x400D7B: main (tester.cpp:54)
==4624== 
==4624== Conditional jump or move depends on uninitialised value(s)
==4624==    at 0x40109E: LinkedList<int>::print() (LinkedList.cc:155)
==4624==    by 0x400D7B: main (tester.cpp:54)

我的 print() 函数的第 153、155、159 行：

153: ListNode<Item> *end = head;
155: while(end != NULL){
159: if(end->next != NULL)

所以我得出的结论是 end 永远不会被初始化，这意味着 head 是 NULL 或设置为一些垃圾值......有人对此有任何想法吗？我哪里错了？

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1 回答 1

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看来您想替换该行

curr_node = &((*curr_node)->next);

和

*curr_node = &(node->next);

因为在 while 循环中curr_node被设置为较早的值。new ListNode<Item>

只是好奇，为什么 curr_node 是指向节点的指针？

于 2013-10-22T00:15:32.293 回答