Question

我正在尝试创建一个双链表，并且有两个函数：首先将元素添加到尾部，第二个应该在开始时添加元素，但它不起作用。

void AddNodeEnd (char addData)
    {
        nodePtr NewNode = new node;
        NewNode->next = NULL;
        NewNode->data = addData;


        if (head != NULL)
        {
            curr = head;
            while(curr->next != NULL)
            {
                curr = curr->next;
            }
            curr->next = NewNode;
        }
        else
        {
            head = NewNode;
        }
    }
    void AddNodeHead (char addData)
    {
        nodePtr NewNode = new node;
        NewNode->prev = NULL;
        NewNode->data = addData;

        head->prev = NewNode;
        NewNode->next = head;
        NewNode->prev = NULL;
    }

Answer 1

我假设head是指向列表第一个元素的指针。

如果在列表的开头添加新节点，则新节点将成为头部。因此，如果您在列表的开头添加了元素，则必须在结尾处分配：head = newNode。

void AddNodeHead (char addData)
{
    nodePtr NewNode = new node;
    NewNode->prev = NULL;
    NewNode->data = addData;

    if ( head != NULL )     // consider an empty list
      head->prev = NewNode;
    NewNode->next = head;   // this also works for an empty list
    head = newNode;         // <- this is missing in your code
}

Answer 2

在添加节点时，您不必将void AddNodeHead (char addData) { ... NewNode->next = head; NewNode->prev = NULL; // you have this twice, not needed }更新为新节点。

至于其他功能：

head

如果NULL是prev怎么办？您将尝试访问其<input type="text" placeholder="Enter your Email" ng-model="email" required> <input type="text" placeholder="Enter your password " ng-model="password" required>成员，从而导致运行时错误。

向主题

2 个答案: