【C语言】双链表（可记录遍历点，根据记录继续遍历）

text1-1.h/* * 链表演示 * */#ifndef __TEXT1_1_H__#define __TEXT1_1_H__typedef struct node {    int num;    struct node *p_next;    struct node *p_pre;} node;typedef struct {    node head;    node tail;    node *p_cur; //记录遍历过程中上一个被处理的节点} link;?//链表的初始化函数void link_init(link *);//清理函数void link_deinit(link *); //计算有效数字个数int link_size(const link *); //判断链表是否为空int link_empty(const link *);//判断是否为满int link_full(const link *);//在链表前面加入新节点void link_add_head(link *, int);//在原有节点最后加入新节点void link_append(link *, int);//按顺序插入void link_insert(link *, int);//删除最前面的有效数字int link_remove_head(link *);//删除最后一个有效节点int link_remove_tail(link *);//删除某个数字所在节点int link_remove(link *, int);//获得链表最前面的数字int link_get_head(const link *, int *);//获得最后面的有效数字int link_get_tail(const link *, int *);//根据编号获得数字int link_get(const link *, int, int *);//将遍历位置指针设置为开始从前往后遍历状态void link_begin(link *);//遍历过程中处理下一个节点int link_next(link *,int *);//将遍历位置记录与尾捆绑，从后向前遍历void link_rbegin(link *);//在从后向前的遍历过程中处理下一个节点int link_pre(link *, int *);#endif //__TEXT1_1_H--------------------------------------------------------------------------------text1.c/* * 链表演示 * 双向 ，记录遍历位置 * 记录遍历的位置需要再增加一个独立的节点link，这个节点用来记录当前遍历的位置和值， * 要注意在增加和删除节点的时候是需要将记录点赋值为空的，否则容易删除该节点，产生野指针 * */#include <stdlib.h>#include "text1-1.h"//链表的初始化函数void link_init(link *p_link) {    p_link->head.p_next = &(p_link->tail);    p_link->tail.p_next = NULL;    //下面是另一个方向的，从尾指向头    p_link->tail.p_pre = &(p_link->head);    p_link->head.p_pre = NULL;    p_link->p_cur = NULL;//该点为空代表此时没有开始遍历}//链表的清理函数void link_deinit(link *p_link) {    while (p_link->head.p_next != &(p_link->tail)) {        node *p_first = &(p_link->head);        node *p_mid = p_first->p_next;        node *p_last = p_mid->p_next;        p_first->p_next = p_last;//清理正向        p_last->p_pre = p_first;//清理反向，就的指针的方向反了一下        free(p_mid);        p_mid = NULL;    }    p_link->p_cur = NULL;// 清空记录点}//计算有效数字个数的函数，正反一样，要修改可以让p_first,p_mid,p_last,从后面开始来int link_size(const link *p_link) {    int cnt = 0;    const node *p_node = NULL;    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        const node *p_first = p_node;        const node *p_mid = p_first->p_next;        const node *p_last = p_mid->p_next;        if (p_mid != &(p_link->tail)) {            cnt++;        }    }    return cnt;}//判断链表是否空的函数int link_empty(const link *p_link) {    return p_link->head.p_next == &(p_link->tail);}//判断链表是否满的函数int link_full(const link *p_link) {    return 0;}//在链表前边加入新节点的函数void link_add_head(link *p_link, int val) {    node *p_first = NULL, *p_mid = NULL, *p_last = NULL;    node *p_tmp = (node *)malloc(sizeof(node));    if (!p_tmp) {        return ;    }    p_tmp->num = val;    p_tmp->p_next = NULL;//正向指针    p_tmp->p_pre = NULL;//反向指针    p_first = &(p_link->head);    p_mid = p_first->p_next;    p_last = p_mid->p_next;    p_first->p_next = p_tmp;    p_tmp->p_pre = p_first;//反向    p_tmp->p_next = p_mid;    p_mid->p_pre = p_tmp;//反向    p_link->p_cur = NULL;}//在原有节点最后加入新节点的函数void link_append(link *p_link, int val) {    node *p_first = NULL, *p_mid = NULL, *p_last = NULL;    node *p_tmp = (node *)malloc(sizeof(node));    if (!p_tmp) {        return ;    }    p_tmp->num = val;    p_tmp->p_next = NULL;//正向    p_tmp->p_pre = NULL;//反向    p_first = p_link->tail.p_pre;//反向添加最后一个节点就是这里不同，原来是first指向头，现在是指向尾，相当于反着来了    p_mid = p_first->p_next;    p_last = p_mid->p_next;    //把新节点加入到p_first和p_mid中间    p_first->p_next = p_tmp;//正    p_tmp->p_pre = p_first;//反    p_tmp->p_next = p_mid;//正    p_mid->p_pre = p_tmp;//反    p_link->p_cur = NULL;}/*void link_append(link *p_link, int val) {    node *p_tmp = (node *)malloc(sizeof(node));    node *p_node = NULL;    if (!p_tmp) {        return ;    }    p_tmp->num = val;    p_tmp->p_next = NULL;    p_tmp->p_pre = NULL;    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        node *p_first = p_node;        node *p_mid = p_first->p_next;        node *p_last = p_mid->p_next;        if (p_mid == &(p_link->tail)) {            p_first->p_next = p_tmp;            p_tmp->p_pre = p_first;            p_tmp->p_next = p_mid;            p_mid->p_pre = p_tmp;            break;        }    }}*///按顺序插入函数void link_insert(link *p_link, int val) {    node *p_tmp = (node *)malloc(sizeof(node));    node *p_node = NULL;    if (!p_tmp) {        return ;    }    p_tmp->num = val;    p_tmp->p_next = NULL;    p_tmp->p_pre = NULL;    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        node *p_first = p_node;        node *p_mid = p_first->p_next;        node *p_last = p_mid->p_next;        if (p_mid == &(p_link->tail) || p_mid->num > val) {            p_first->p_next = p_tmp;            p_tmp->p_pre = p_first;//反向            p_tmp->p_next = p_mid;            p_mid->p_pre = p_tmp;//反向            break;        }    }    p_link->p_cur = NULL;}//删除最前面有效数字的函数int link_remove_head(link *p_link) {    node *p_first = NULL, *p_mid = NULL, *p_last = NULL;    if (link_empty(p_link)) {        return 0;    }    p_first = &(p_link->head);    p_mid = p_first->p_next;    p_last = p_mid->p_next;    p_first->p_next = p_last;//正    p_last->p_pre = p_first;//反    free(p_mid);    p_mid = NULL;    p_link->p_cur = NULL;//记录当前遍历位置    return 1;}//删除最后一个有效节点的函数int link_remove_tail(link *p_link) {    node *p_first = NULL, *p_mid = NULL, *p_last = NULL;    if (link_empty(p_link)) {        return 0;    }    p_first = p_link->tail.p_pre->p_pre;//尾节点->最后一个有效节点->倒数第二个有效节点    p_mid = p_first->p_next;//最后一个有效节点    p_last = p_mid->p_next;    //把p_mid指针捆绑的节点从链表里    //摘出来    p_first->p_next = p_last;    p_last->p_pre = p_first;    free(p_mid);    p_mid = NULL;    p_link->p_cur = NULL;    return 1;}/*int link_remove_tail(link *p_link) {    node *p_node = NULL;    if (link_empty(p_link)) {        return 0;    }    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        node *p_first = p_node;        node *p_mid = p_first->p_next;        node *p_last = p_mid->p_next;        if (p_last == &(p_link->tail)) {            p_first->p_next = p_last;            p_last->p_pre = p_first;            free(p_mid);            p_mid = NULL;            break;        }    }    return 1;}*///删除某个数字所在节点的函数int link_remove(link *p_link, int val) {    node *p_node = NULL;    p_link->p_cur = NULL;    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        node *p_first = p_node;        node *p_mid = p_first->p_next;        node *p_last = p_mid->p_next;        if (p_mid != &(p_link->tail) && p_mid->num == val) {            p_first->p_next = p_last;//正            p_last->p_pre = p_first;//反            free(p_mid);            p_mid = NULL;            return 1;        }    }    return 0;}//获得链表最前面数字的函数int link_get_head(const link *p_link, int *p_num) {    const node *p_first = NULL, *p_mid = NULL, *p_last = NULL;    if (link_empty(p_link)) {        return 0;    }    p_first = &(p_link->head);    p_mid = p_first->p_next;    p_last = p_mid->p_next;    *p_num = p_mid->num;    return 1;}//获得最后有效数字的函数int link_get_tail(const link *p_link, int *p_num) {    if (link_empty(p_link)) {        return 0;    }    *p_num = p_link->tail.p_pre->num;    return 1;}/*int link_get_tail(const link *p_link, int *p_num) {    const node *p_node = NULL;    if (link_empty(p_link)) {        return 0;    }    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        const node *p_first = p_node;        const node *p_mid = p_first->p_next;        const node *p_last = p_mid->p_next;        if (p_last == &(p_link->tail)) {            *p_num = p_mid->num;            break;        }    }    return 1;}*///根据编号获得数字的函数int link_get(const link *p_link, int num, int *p_num) {    int cnt = 0;    const node *p_node = NULL;    for (p_node = &(p_link->head);p_node != &(p_link->tail);p_node = p_node->p_next) {        const node *p_first = p_node;        const node *p_mid = p_first->p_next;        const node *p_last = p_mid->p_next;        if (p_mid != &(p_link->tail) && num == cnt) {            *p_num = p_mid->num;            return 1;        }        cnt++;    }    return 0;}//将遍历位置指针设置为开始从前往后遍历状态void link_begin(link *p_link) {    p_link->p_cur = &(p_link->head);//将记录指针与头捆绑，下一个要处理的就是第一个有效节点}//遍历过程中处理下一个节点int link_next(link *p_link, int *p_num) {//因为不确定是否可以成功的获得，所以需要有返回来确定状态    if(!(p_link->p_cur)) {//如果不处于遍历状态，也就是记录指针为0时        return 0;    }    p_link->p_cur = p_link->p_cur->p_next;//找到这次要处理的节点并记录到p_cur指针里面    if(p_link->p_cur == &(p_link->tail)) {        p_link->p_cur = NULL;        return 0;    }    else {        *p_num = p_link->p_cur->num;        return 1;    }}//将遍历位置记录与尾捆绑，从后向前遍历void link_rbegin(link *p_link) {    p_link->p_cur = &(p_link->tail);}//在从后向前的遍历过程中处理下一个节点int link_pre(link *p_link, int *p_num) {    if(!(p_link->p_cur)) {        return 0;    }    p_link->p_cur = p_link->p_cur->p_pre;    if(p_link->p_cur == &(p_link->head)) {        p_link->p_cur = NULL;        return 0;    }    else {        *p_num = p_link->p_cur->num;        return 1;    }}--------------------------------------------------------------------------------text2.c:/* * 链表测试 * */#include <stdio.h>#include "text1-1.h"int main() {    int size = 0;    int num = 0, val = 0;    link lnk = {0};    link_init(&lnk);    link_deinit(&lnk);    link_add_head(&lnk, 30);    link_add_head(&lnk, 10);    link_append(&lnk, 80);    link_append(&lnk, 100);    link_insert(&lnk, 20);    link_insert(&lnk, 90);    link_insert(&lnk, 50);    link_insert(&lnk, 60);    link_insert(&lnk, 40);    link_insert(&lnk, 70);    link_remove_head(&lnk);    link_remove_tail(&lnk);    link_remove(&lnk, 70);    size = link_size(&lnk);    printf("数字个数是：%d\n", size);/*    for(num = 0; num < size -1; num++){        link_get(&lnk, num, &val);        printf("%d ", val);    }*/    link_begin(&lnk);    while(1) {        if(!link_next(&lnk, &val)){//如果返回值是零就停止            break;        }        printf("%d ", val);    }    printf("\n");    link_rbegin(&lnk);    while(1) {        if(!link_pre(&lnk, &val)) {            break;        }        printf("%d ", val);    }    printf("\n");    link_deinit(&lnk);    return 0;}