链表节点的增加和删除

struct ListNode
{
	int m_nValue;
	ListNode* m_pNext;
};

//增加节点
/*第一个参数是一个指向指针的指针。当我们往一个空链表中插入一个节点时，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*/
void addToTail(ListNode** pHead, int value)								
{
	ListNode* pNew = new ListNode();
	pNew->m_pNext = NULL;
	pNew->m_nValue = value;

	if(*pHead == NULL)
	{
		*pHead = pNew;
	}
	else
	{
		ListNode* pNode = *pHead;	//用临时节点来遍历链表以找出最后一个末尾基点

		while(pNode->m_pNext)
			pNode = pNode->m_pNext;

		pNode->m_pNext = pNew;
	}
}

void removeNode(ListNode** pHead, int value)
{
	if(*pHead == NULL || pHead == NULL)
		return;
	
	ListNode* pToBeDelete = NULL;	//要被删除的节点放入pToBeDelete
	if((*pHead)->m_nValue == value)	//如果是头结点要被删除
	{
		pToBeDelete = *pHead;
		*pHead = (*pHead)->m_pNext;	//改变头结点
	}
	else
	{
		ListNode* pNode = *pHead;

		while(pNode->m_pNext != NULL && pNode->m_pNext->m_nValue != value)
		{
			pNode = pNode->m_pNext;	//寻找被删除节点的上一个节点
		}
		//找到节点
		if(pNode->m_pNext != NULL && pNode->m_pNext->m_nValue != value == value)
		{
			pToBeDelete = pNode->m_pNext;
			pNode->m_pNext = pNode->m_pNext->m_pNext;	//调整节点
		}
	}
	
	if(pToBeDelete != NULL)
	{
		delete pToBeDelete;	//删除节点
	}
}