C语言数据结构-----双向链表增删查改的代码实现

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链接: 顺序表(动态顺序表增删查改的代码实现) 链接:
单链表(无头单向不循环)增删查改的代码实现
往期顺序表，单链表的代码实现

完整代码见gitee：
链接: 双向链表增删查改的代码实现

1.初始化双链表

LTNode* LTInit()
{
    
    
	LTNode* phead = CreateLTNode(-1);
	phead->next = phead;
	phead->prev = phead;

	return phead;
}

2.创建链表节点

LTNode* CreateLTNode(LTDataType x)
{
    
    
	LTNode* newnode = (LTNode*)malloc(sizeof(LTNode));
	if (newnode == NULL)
	{
    
    
		perror("malloc fail");
		exit(-1);
	}

	newnode->val = x;
	newnode->next = NULL;
	newnode->prev = NULL;

	return newnode;
}

3.打印链表

void LTPrint(LTNode* phead)
{
    
    
	assert(phead);
	printf("哨兵位<=>");

	LTNode* cur = phead->next;
	while (cur != phead)
	{
    
    
		printf("%d<=>", cur->val);
		cur = cur->next;
	}
	printf("\n");
}

4.尾插

void LTPushBack(LTNode* phead, LTDataType x)
{
    
    
//第一种
	assert(phead);
	LTNode* tail = phead->prev;
	LTNode* newnode = CreateLTNode(x);
	//phead               tail  newnode
	tail->next = newnode;
	newnode->prev = tail;
	newnode->next = phead;
	phead->prev = newnode;
//第二种
	//LTInsert(phead, x);
}

5.尾删

void LTPopBack(LTNode* phead)
{
    
    
//第一种
	assert(phead);
	assert(phead->next != phead);
	LTNode* tail = phead->prev;
	LTNode* tailPrev = tail->prev;
	free(tail);
	tailPrev->next = phead;
	phead->prev = tailPrev;
//第二种
	//LTErase(phead->prev);
}

6.头插

void LTPushFront(LTNode* phead, LTDataType x)
{
    
    
//第一种
	assert(phead);
	LTNode* newnode = CreateLTNode(x);
	LTNode* first = phead->next;
	phead->next = newnode;
	newnode->prev = phead;
	newnode->next = first;
	first->prev = newnode;
//第二种
	//LTInsert(phead->next, x);
}

7.头删

void LTPopFront(LTNode* phead)
{
    
    
//第一种
	assert(phead);
	assert(phead->next != phead);
	LTNode* first = phead->next;
	LTNode* second = first->next;
	phead->next = second;
	second->prev = phead;
	free(first);
	first = NULL;
	//第二种
	//LTErase(phead->next);
}

8.在pos之前插入

void LTInsert(LTNode* pos, LTDataType x)
{
    
    
	assert(pos);
	LTNode* posPrev = pos->prev;
	LTNode* newnode = CreateLTNode(x);
	// posprev newnode pos
	posPrev->next = newnode;
	newnode->prev = posPrev;
	newnode->next = pos;
	pos->prev = newnode;
}

8.1 在pos之前插入(改造头插)

LTInsert(phead->next, x);

8.2 在pos之前插入(改造尾插)

LTInsert(phead, x);

9.删除pos位置

void LTErase(LTNode* pos)
{
    
    
	assert(pos);

	LTNode* posNext = pos->next;
	LTNode* posPrev = pos->prev;

	posPrev->next = posNext;
	posNext->prev = posPrev;
	free(pos);
	pos = NULL;
}

9.1 删除pos位置(改造尾删)

LTErase(phead->prev);

9.1 删除pos位置(改造头删)

LTErase(phead->next);

10.查找

LTNode* LTFind(LTNode* phead, LTDataType x)
{
    
    
	assert(phead);

	LTNode* cur = phead->next;
	while (cur != phead)
	{
    
    
		if (cur->val == x)
		{
    
    
			return cur;
		}

		cur = cur->next;
	}

	return NULL;
}

11.毁灭

void LTDestroy(LTNode* phead)
{
    
    
	assert(phead);

	LTNode* cur = phead->next;
	while (cur != phead)
	{
    
    
		LTNode* next = cur->next;
		free(cur);
		cur = next;
	}

	free(phead);
	phead = NULL;
}

完整代码见gitee： 链接:
双向链表增删查改的代码实现