C的双向链表实现

最近写了链表的实现。先贴代码。

（代码是在linux gcc下编译，有可能和vs上编译有差别）

1，双向链表的实现：

/** 
*@breif带头结点的双向链表的实现 
*@authorLinf *@data2012-12-28 10:45 
*@detail实现双向链表的一系列操作。init,insert,delete,print...etc 
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct _doublelist{
    int num;
    struct _doublelist *next;
    struct _doublelist *down;
}doublelist;

/**
*func:初始化双向链表
*param:NULL
*return:struct doublelist's point
*/
static doublelist* initDoubleList()
{
    doublelist* list = NULL;
    list = (doublelist *)malloc(sizeof(doublelist));
    if(list == NULL)
    return NULL;
    list->next = NULL;
    list->down = NULL;
    return list;
}

/**
*func:计算链表的长度
*param：head - 头结点
*return：NULL
*/
static int numDoubleList(doublelist* head)
{
    int len = 0;
    while(head->next)
    {
        len++;
        head = head->next;
    }
    return len;
}

/**
*func:打印双向链表
*param:list - 双向链表的头结点
*return：NULL
*/
static void printDoubleList(doublelist* list)
{
    doublelist* head = list;
    printf("------------next------------\n");
    while(head->next)
    {
        printf("data:%d\n", head->next->num);
        head = head->next; 
    }
    printf("------------next------------\n");
    head = list;
    printf("------------down------------\n"); 
    while(head->down)
    {
        printf("data:%d\n", head->down->num);
        head = head->down;
    }
    printf("------------down------------\n");
    return ;
}

/**
*func：释放资源，very important。防止内存泄露
平时编程也要注意。慢慢养成良好的编程习惯。慢慢的就习以为常了。哈哈
*param:list - 头结点
*return：NULL
*/
static void freeDoubleList(doublelist** list)
{
    doublelist* head = NULL;
    doublelist* now = NULL;
    head = *list;
    while(head -> next)
    {
        now = head->next;
        head = head->next;
        if(now)
        {
            free((void *)now);
            now = NULL;
        }
    }
    printf("free doublelist ok\n");
    return ;
}

/**
*func：通过num值的大小顺序插入双向链表节点。(num类型可扩展)
*param：list -- 头结点指针的指针，num -- 插入的num值
*return: 0 success insert. -1 failed insert
*/
static int insertDoubleList(doublelist** list , int num)
{
    doublelist* head = *list;
    doublelist* downhead = *list;
    if(head == NULL)
        return -1;
    doublelist* point = NULL;
    point = initDoubleList();
    if(point == NULL)
        return -1;
    point->num = num;
    //双向链表中还没有节点，
    if(head ->next == NULL || head->down == NULL)
    {
        head->next = point;
        head->down = point;
        return 0;
    }
    while(head->next && head->next->num <= num)
        head = head->next;
    //插入到最后
    if(head->next == NULL)
    {
        head->next = point;
        point->down = head;
        downhead->down = point;
    }
    //插入到中间
    else
    {
        point->next = head->next;
        point->down = head;
        head->next->down = point;
        head->next = point;
    }
    return 0;
}

/**
*func:通过location删除相应的节点
(其实这个接口的实用价值不大。只是方便操作。just it)
注意删除的节点要free。否则内存泄露
*param:list -- 双向链表指针的指针。(实际传的是存储双向链表指针的地址 ), location -- 删除的位置
*return: 0 success delete. -1 failed delete
*/
static int deleteDoubleList(doublelist** list, int location)
{
    doublelist* head = *list;
    doublelist* now = NULL;
    doublelist* last = NULL;
    if(head == NULL)
        return -1;
    //先判断location的合法性
    if(location <= 0 || location > numDoubleList(head))
        return -1;
    //删除第一个特殊判断处理
    if(location == 1)
    {
        now = head->next;
        head->next = now->next;
        head->next->down = NULL;
        if(now)
        {
            free((void *)now);
            now = NULL;
        }
        return 0;
    }
    int num = 0;
    while(head->next && num++ < location)
        head = head->next;
    //删除最后一个节点
    if(head->next == NULL)
    {
        now = *list;  
        head->down->next = NULL;
        now->down = head->down;
        if(head)
        {
            free((void *)head);
            head = NULL;
        }
    }
    //删除中间的节点
    else
    {
        printf("line=%d\n", __LINE__);
        now = head->next;
        last = head->down;
        now->down = head->down;
        last->next = head->next;
        if(head)
        {
            free((void *)head);
            head = NULL;
        }
    } 
    return 0;
}

int main(int argc, char** argv)
{
    doublelist* head = initDoubleList();
    if(head == NULL)
        return -1;
    insertDoubleList(&head, 3);
    insertDoubleList(&head, 5);
    insertDoubleList(&head, 4);
    printDoubleList(head);
    deleteDoubleList(&head, 1);
    printDoubleList(head);
    freeDoubleList(&head);
    return 0;
}