链表的插入和删除

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/* * 往链表的末尾插入一个节点和在链表中查找某个节点并删除 */   #include<iostream>   using namespace std;   struct ListNode {     int m_nValue;     ListNode* m_pNext; };   //往一个链表的尾部添加一个节点 void AddToTail(ListNode ** pHead, int value) {     ListNode* pNew = new ListNode();     pNew->m_nValue = value;     pNew->m_pNext = nullptr;       if (*pHead == nullptr)     {         *pHead = pNew;     }     else     {         ListNode* pNode = *pHead;           while (pNode->m_pNext != nullptr)         {             pNode = pNode->m_pNext;         }           pNode->m_pNext = pNew;     } }   //在链表中查找某个节点，并将该节点删除 void RemoveNode(ListNode** pHead, int value) {     if (pHead == nullptr || *pHead == nullptr)     {         return;     }       ListNode* pToBeDeleted = nullptr;     if ((*pHead)->m_nValue == value)     {         pToBeDeleted = *pHead;         *pHead = (*pHead)->m_pNext;     }     else     {         ListNode* pNode = *pHead;         while (pNode->m_pNext != nullptr && pNode->m_pNext->m_nValue != value)         {             pNode = pNode->m_pNext;         }           if (pNode->m_pNext != nullptr && pNode->m_pNext->m_nValue == value)         {             pToBeDeleted = pNode->m_pNext;             pNode->m_pNext = pNode->m_pNext->m_pNext;         }     }       if (pToBeDeleted != nullptr)     {         delete pToBeDeleted;         pToBeDeleted = nullptr;     } }   int main() {     ListNode* pList = nullptr;     AddToTail(&pList, 1);     AddToTail(&pList, 2);       RemoveNode(&pList, 1);     RemoveNode(&pList, 2);       return 0; }   /* * 我们要特别注意函数的第一个参数pHead是一个指向指针的指针。当我们向一个空链表中 * 插入一个节点的时候，新插入的节点就是链表的头指针。由于此时会改动头指针，因此必须 * 把pHead参数设为指向指针的指针，否则出了这个函数pHead仍然时一个空指针。 */