C语言——带头节点单链表常见操作

#include <stdio.h>#include <stdlib.h>typedef struct stu{    int data;  //存放数据    struct stu* next; //下一个节点地址}Node;typedef struct{    int count;  // 节点个数    Node* head; // 头结点}List;//创建新节点功能Node* Create_node(int data){    Node* pnew = (Node*)malloc(sizeof(Node));//为新节点开辟空间    pnew->next = NULL;     //新节点指向null;    pnew->data = data;    return pnew;}//头部插入数据void push_head(List* p, int data){    //创建一个新的节点    Node*pn = Create_node(data);    //插入新节点到表头    pn->next = p->head;    p->head = pn;    p->count++;}//尾插void push_tail(List* p, int data){    //找到最后一个节点    Node* pn = p->head;    while (pn->next != NULL)    {        pn = pn->next;    }    //插入元素    Node*pm = Create_node(data);    pn->next = pm;    p->count++;}//头删节点void del_head(List* p){    Node* pn = p->head;//把要删除的节点保存起来    p->head = p->head->next;//连接它的前节点与后节点    free(pn);//释放并置为空    pn = NULL;    p->count--;}//尾删节点void del_tail(List* p){    Node *pn = p->head;//第一个节点    while (pn->next->next != NULL)    {        pn = pn->next;    }    Node*pm = pn->next->next;    pn->next = NULL;    free(pm);    pm = NULL;    p->count--;}//任一位置节点插入void push_arb(List* p, int data, int pos){    //判断插入位置是否合法    if (pos<0 || pos>p->count)    {        printf("插入位置不合法，插入到尾部\n");        pos = p->count;    }    //头插    if (pos == 0)    {        Node*pn = Create_node(data);        pn->next = p->head;        p->head = pn;        p->count++;        return;    }    //中间任意位置插入    Node*pn = Create_node(data);    Node*pm = p->head;    for (int i = 1; i < pos; i++)    {        pm = pm->next;    }    pn->next = pm->next;    pm->next = pn;    p->count++;}//任一节点删除void del_arb(List* p, int pos){    //判断删除位置是否合法    if (pos<0 || pos >= p->count)//删除的是当前位置后面的一个节点    {        printf("删除位置不合法，删除失败\n");        return;    }    Node*pn = p->head;    if (pos == 0)//头删    {        p->head = p->head->next;        free(pn);        p->count--;        return;    }    //任意位置删除    for (int i = 1; i < pos; i++)    {        pn = pn->next;    }    Node*pm = pn->next;    pn->next = pn->next->next;    free(pm);    pm = NULL;    p->count--;}//从尾到头打印链表递归调用void tail_head(Node*head)//递归方法{    if (head == NULL)    {        return;    }    tail_head(head->next);    printf("%d  ", head->data);}//链表长度void long_list(List* p){    printf("%d\n", p->count);}//清空链表void clear_list(List* p)//从头开始清空{    printf("清空所有的节点\n");    //第一个数据    while (p->head != NULL)    {        Node*pn = p->head;        p->head = p->head->next;        free(pn);        pn = NULL;        p->count--;    }}//遍历链表void travel_list(List* p){    Node* ptemp = p->head;    if (ptemp == NULL)    {        printf("链表已空\n");        return;    }    printf("链表中元素有： ");    while (ptemp != NULL)    {        printf("%d   ", ptemp->data);        ptemp = ptemp->next;    }    printf("\n");}int main(){    List list;    list.head = NULL;    list.count = 0;    push_head(&list, 1);    push_head(&list, 2);    push_head(&list, 3);    travel_list(&list);    push_tail(&list, 4);    travel_list(&list);    del_head(&list);    travel_list(&list);    del_tail(&list);    travel_list(&list);    long_list(&list);    clear_list(&list);    long_list(&list);    push_arb(&list, 6, 9);    push_arb(&list, 6, 1);    travel_list(&list);    tail_head(list.head);    travel_list(&list);    return 0;}