双向循环链表

• 初始化
• 添加元素
• 删除元素
• 输出整个链表

实现代码

/*
 * bidirectional circular linked list
 */
#include <stdio.h>
#include <stdlib.h>

struct bclist {
        struct bclist *next;
        struct bclist *prev;
        int data;
};

struct bclist* bclist_init(int data)
{
        struct bclist *p = malloc(sizeof(struct bclist));
        if(p) {
                p->next = p;
                p->prev = p;
                p->data = data;
        }
        return p;
}

struct bclist* bclist_add(struct bclist* h, int data)
{
        struct bclist *p = h;

        if(NULL == h) {
                return h;
        }

        do {
                if(p->data == data) {
                        return h;
                }
                p = p->next;
        }while(p != h);

        p = malloc(sizeof(struct bclist));
        if(NULL == p) {
                return h;
        }
        p->next = h;
        p->prev = h->prev;
        h->prev = p;
        p->prev->next = p;

        p->data = data;

        return h;
}

struct bclist* bclist_delete(struct bclist* h, int data)
{
        struct bclist *p = h;
        struct bclist *q = NULL;

        do {
                if(p->data == data) {
                        q = p;
                        p = p->prev;
                        q->next->prev = q->prev;
                        q->prev->next = q->next;
                        free(q);
                }
                p = p->next;
        } while(p != h);

        return h;
}

struct bclist* bclist_free(struct bclist* h)
{
        struct bclist* p = h;
        do {
                p = p->next;
        } while(p != h);

        return h;
}

void bclist_print(struct bclist* h)
{
        struct bclist* p = h;

        do {
                printf("%d ", p->data);
                p = p->next;
        }while(p != h);

        printf("\n");
}

int main(int argc, char** argv)
{
        const int ret = 0;
        struct bclist* h = NULL;

        h = bclist_init(0);
        bclist_add(h, 1);
        bclist_add(h, 2);
        bclist_add(h, 3);
        bclist_add(h, 2);
        bclist_print(h);

        bclist_delete(h, 2);
        bclist_add(h, 5);
        bclist_print(h);

        return ret;
}

尚未实现

• bclist_free删除链表所有元素