双链表的操作

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

typedef struct _dlink_node_ {
    int data;
    struct _dlink_node_ *pre;
    struct _dlink_node_ *next;
}dlinknode_st;

dlinknode_st *dlist_init();
int dlist_free(dlinknode_st *h);
int head_insert(dlinknode_st *h, int value);
int dlist_show(dlinknode_st *h);
int dlist_delete(dlinknode_st *h, int obj);
dlinknode_st *dlist_locate(dlinknode_st *h, int obj);
int dlist_search(dlinknode_st *h, int obj);
int dlist_modify(dlinknode_st *h, int old, int new);

int main()
{
    dlinknode_st *list = NULL;
    int obj;

    if (NULL == (list = dlist_init()))
        return -1;

    puts("listshow:");
    head_insert(list, 100);
    head_insert(list, 200);
    head_insert(list, 300);
    head_insert(list, 200);
    head_insert(list, 300);
    head_insert(list, 200);
    head_insert(list, 300);
    head_insert(list, 200);
    dlist_show(list);

    puts("delete:");
    dlist_delete(list, 200);
    dlist_show(list);


    puts("modify:");
    dlist_modify(list, 100, 1000);
    dlist_show(list);

    obj = 100;
    puts("search:");
    if (dlist_search(list, obj))
        printf("%d is exist!\n", obj);
    else
        printf("%d is not exist\n", obj);

    dlist_free(list);

    return 0;
}

dlinknode_st *dlist_init()
{
    dlinknode_st *h = NULL;

    if (NULL == (h = (dlinknode_st *)malloc(sizeof(dlinknode_st)))) {
        puts("fail to create!");
        return NULL;
    }

    h->data = 0;
    h->next = NULL;
    h->pre = NULL;

    return h;
}

int dlist_free(dlinknode_st *h)
{
    dlinknode_st *p = h, *tmp = NULL;

    while (NULL != p) {
        tmp = p;
        p = p->next;
        free(tmp);
        tmp = NULL;
    }

    return 0;
}

int head_insert(dlinknode_st *h, int value)
{
    dlinknode_st *new = NULL;

    if (NULL == (new = (dlinknode_st *)malloc(sizeof(dlinknode_st)))) {
        puts("fail to create!");
        return -1;
    }

    new->data = value;

    new->next = h->next;
    if (NULL != new->next)
        new->next->pre = new;
    new->pre = h;
    h->next = new;

    return 0;
}

int dlist_show(dlinknode_st *h)
{
    dlinknode_st *p = h;

    while (NULL != p->next) {
        printf("%5d", p->next->data);
        p = p->next;
    }

    putchar(10);

    while (NULL != p->pre) {
        printf("%5d", p->data);
        p = p->pre;
    }

    putchar('\n');

    return 0;
}

int dlist_delete(dlinknode_st *h, int obj)
{
    dlinknode_st *p = h, *tmp = NULL;

    while (NULL != p->next) {
        if (p->next->data == obj) {
            tmp = p->next;
            p->next = tmp->next;
            tmp->next->pre = p;
            free(tmp);
            tmp = NULL;
        } else
            p = p->next;
    }

    return 0;
}

dlinknode_st *dlist_locate(dlinknode_st *h, int obj)
{
    dlinknode_st *p = h;

    while (NULL != p->next && p->next->data != obj)
        p = p->next;

    if (NULL == p->next)
        return NULL;

    return p;
}

int dlist_search(dlinknode_st *h, int obj)
{
    if (NULL == dlist_locate(h, obj))
        return 0;

    return 1;
}

int dlist_modify(dlinknode_st *h, int old, int new)
{
    dlinknode_st *p = h;

    while (NULL != p->next) {
        if (p->next->data == old)
            p->next->data = new;

        p = p->next;
    }

    return 0;
}