循环双向链表

双向循环链表：每个节点都含有指向上一个节点（pre）和下一个节点（next）的指针，因此整个链表可以往两个方向，最后一个节点的next指向头结点，头结点的pre指向尾节点，因此是循环链表。

节点数据：

typedef int datatype;typedef struct list{datatype data;struct list *pre,*next;}doublelist,*pdoublelist;

/* 初始化双向链表头结点 */void DoubleList_Init(pdoublelist *Head){*Head = (pdoublelist)malloc(sizeof(doublelist));if(NULL == *Head){perror("malloc");exit(1);}/* 让头结点的pre和next指向自己 */(*Head)->pre = *Head;(*Head)->next = *Head;}/* 插入到头节点 */void DoubleList_InsertHead(pdoublelist Head,pdoublelist node){node->next = Head->next;Head->next->pre = node;/* 上下两句代码不可调换 */node->pre = Head;Head->next = node;}/* 插入到尾节点 */void DoubleList_InsertTail(pdoublelist Head,pdoublelist node){node->pre = Head->pre;Head->pre->next = node;/* 上下两句代码不可调换 */node->next = Head;Head->pre = node;}/* 删除指定数据的节点 */int DoubleList_Delete(pdoublelist Head,datatype data){pdoublelist temp = Head;while(temp->next!=temp){temp = temp->next;/* 找到要删除的节点 */if(temp->data==data){temp->next->pre = temp->pre;temp->pre->next = temp->next;free(temp);printf("删除节点成功\n");return 0;}}printf("没有知道该节点\n");}/* 为链表创建指定个节点数据 */void DoubleList_Create(pdoublelist Head,int n){int i;pdoublelist new;datatype input;for(i = 0; i < n; i++){new = (pdoublelist)malloc(sizeof(doublelist));if(NULL == new){perror("melloc");exit(1);}printf("请输入第%d个节点的数据：",i+1);scanf("%d",&new->data);/*  把新节点放入链表 */DoubleList_InsertHead(Head,new); //放入到头结点//DoubleList_InsertTail(Head,new); //放入到尾结点}}/* 遍历双向循环链表 */void DoubleList_each(pdoublelist Head){pdoublelist temp;printf("双向链表循环数据:");for(temp = Head->next; temp!=Head; temp = temp->next){printf(" %d",temp->data);}printf("\n");}

测试程序：

int main(void){datatype data;pdoublelist head;DoubleList_Init(&head);DoubleList_Create(head,5);DoubleList_each(head);printf("请输入要删除的数据:");scanf("%d",&data);DoubleList_Delete(head,data);DoubleList_each(head);}