Question

我正在尝试打印双向链接循环列表的值，但我的printAll函数仅出于某种原因打印出第一个节点的内容。

#include<stdlib.h>
#include<stdio.h>

struct clientsOn
{
    int id;
    char filename[20];
    struct clientsOn* next;
    struct clientsOn* prev;
};

struct clientsList
{
    int count;
    struct clientsOn* head;
};

void printAll(struct clientsList* list);
void add(struct clientsList *list,struct clientsOn *newC);
struct clientsList* createList();
struct clientsOn* createNode(char* profile);

main()
{
struct clientsList* people = malloc(sizeof(struct clientsList));
people = createList();
printf("Number of people currently on: %d\n",people->count);

struct clientsOn* pers1, *pers2, *pers3;

char boy[20],boy2[20],boy3[20];
printf("String: \n");
scanf("%s",boy);
printf("String: \n");
scanf("%s",boy2);
printf("String: \n");
scanf("%s",boy3);

pers1 = createNode(boy);
pers2 = createNode(boy2);
pers3 = createNode(boy3);

add(people,pers1);
add(people,pers2);
add(people,pers3);
printf("people count: %d", people->count);

printAll(people);
}

struct clientsList* createList()
{
    struct clientsList* list = malloc(sizeof(struct clientsList));
    if(list){
        list->head = NULL;
        list->count = 0;
    }
    return list;
}

struct clientsOn* createNode(char* profile)
{
    struct clientsOn* clients = malloc(sizeof(struct clientsOn));

    if(clients){
        clients->next = clients;
        clients->prev = clients;
        strcpy(clients->filename,profile);
    }
    return clients;
}

void add(struct clientsList *list,struct clientsOn *newC)
{

    if(newC){
    if(list->head == NULL){
        list->head = newC;
    }else{
        list->head->prev = newC;
        newC->prev = list->head->prev;
        newC->prev->next = newC;
        newC->next = list->head;
    }
    list->count++;
    }
}

void printAll(struct clientsList* list)
{
    struct clientsOn* node = list->head;

    if(node != NULL){
        do{
            printf("list content is: %s",node->filename);
            node = node->next;
        }while(node!=list->head);
    }
}

我的添加功能将节点添加到列表的最末端，当我输出列表计数

时

printf("people count: %d", people->count);

它显示了添加到列表中的项目数，但是当我尝试打印出单个项目时，

printAll(people);

它不会超越第一个节点。有没有人经历过类似的事情？

Answer 1

在add()函数中，存在无法正确创建列表的问题。

list->head->prev = newC;  //sets head->prev to newC
newC->prev = list->head->prev; //here setting newC->prev to head->prev which is NewC
newC->prev->next = newC; //here newC->prev->next is actually newC->next is set to newC

尝试使用gdb或其他调试器验证您的逻辑。

Answer 2

在添加功能中尝试使用此逻辑。我认为它应该有用。

if(newC){
    if(list->head == NULL){
        list->head = newC;
    }else{
        newC->next = list->head;
        newC->prev = list->head->prev;
        list->head->prev->next = newC;
        list->head->prev = newC;
    }
    list->count++;
    }

最好尝试使用GDB，或者如果您想了解逻辑，可以先使用图表。

在c中打印双向链接循环列表的内容仅打印出第一个节点

2 个答案: