删除链表中的节点

Question

嗨，我正在尝试删除链表中的节点。我首先正在尝试如何删除头部和尾部节点。头部删除似乎有效，但删除的尾部不起作用。当我运行代码时，尾巴曾经所在的地方被替换为垃圾值。谁能弄清楚为什么？非常感谢！

void CList :: Remove() {
    int data = NULL;
    std::cout<<"Enter value you wish to remove ";
    std:: cin>> data;
    cNode *pMyPointer = m_pHead;
    while (pMyPointer != NULL)
    {
        if (pMyPointer->m_nValue == data) {
            std::cout << "Element found";
            goto del;
        }
        else {
            pMyPointer = pMyPointer->m_pNext;
        }   
    }
    del:
    //removing the head
    if (pMyPointer == m_pHead)
        m_pHead= m_pHead->m_pNext;
    //removing the tail
    else if (pMyPointer == m_pTail)
        m_pTail = m_pTail->m_pPrev;
    delete pMyPointer;
}

Answer 1

考虑node_1点到node_2（只是一个 2 节点的情况）看看这个代码

else if (pMyPointer == m_pTail)
        m_pTail = m_pTail->m_pPrev;

node_1指向node_2。它仍然指向那里.删除node_2后，node_1仍将指向node_2（或删除node_2后为垃圾），因此必须确保node_1指向NULL。即最后，但应该指向空。

类似的东西

else if (pMyPointer == m_pTail)
    m_pTail->m_pPrev->next=NULL;
    m_pTail = m_pTail->m_pPrev;

Answer 2

用这个语句

 while (pMyPointer != NULL)

您的指针在退出循环时可能指向 NULL，因此它将跳过尾部指针。

而是尝试

while (pMyPointer->m_pNext != NULL)

还需要使倒数第二个节点指向 NULL。

else if (pMyPointer == m_pTail) {
  m_pTail = m_pTail->m_pPrev;
  m_pTail->m_pNext = NULL;
}
delete pMyPointer;

另外，不要goto del，只需使用break;

Answer 3

在要删除的节点之前保留一个节点

Answer 4

如果你的尾巴和头部指针相同怎么办？你不检查它。因此，您可能会删除您认为是头部的指针，这也是一个尾部。另外，如果它是下一个是正面或上一个尾部怎么办？

void CList :: Remove() {
    int data = NULL;
    std::cout<<"Enter value you wish to remove ";
    std:: cin>> data;
    cNode *pMyPointer = m_pHead;
    while (pMyPointer != NULL)
    {
        if (pMyPointer->m_nValue == data) {
            std::cout << "Element found";
            goto del;
        }
        else {
            pMyPointer = pMyPointer->m_pNext;
        }   
    }
    del:
     //taking care of the neighbors
    if (pMyPointer->m_pPrev)
        pMyPointer->m_pPrev->m_pNext = pMyPointer->m_pNext;
    if (pMyPointer->m_pNext)
        pMyPointer->m_pNext->m_pPrev = pMyPointer->m_pPrev;
    // removing the head
    if (pMyPointer == m_pHead)
        m_pHead= m_pHead->m_pNext;
    //removing the tail
    if (pMyPointer == m_pTail)
        m_pTail = m_pTail->m_pPrev;
    delete pMyPointer;
}