双向链表>非循环

（1）定义双向链表的基本结构
    typedef struct _DOUBLE_LINK_NODE  
    {  
        int data;  
        struct _DOUBLE_LINK_NODE* prev;  
        struct _DOUBLE_LINK_NODE* next;  
    }DOUBLE_LINK_NODE;  

    （2）创建双向链表节点
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    DOUBLE_LINK_NODE* create_double_link_node(int value)  
    {  
        DOUBLE_LINK_NODE* pDLinkNode = NULL;  
        pDLinkNode = (DOUBLE_LINK_NODE*)malloc(sizeof(DOUBLE_LINK_NODE));  
        assert(NULL != pDLinkNode);  
      
        memset(pDLinkNode, 0, sizeof(DOUBLE_LINK_NODE));  
        pDLinkNode->data = value;  
        return pDLinkNode;  
    }  

    （3）删除双向链表
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    void delete_all_double_link_node(DOUBLE_LINK_NODE** pDLinkNode)  
    {  
        DOUBLE_LINK_NODE* pNode;  
        if(NULL == *pDLinkNode)  
            return ;  
      
        pNode = *pDLinkNode;  
        *pDLinkNode = pNode->next;  
        free(pNode);  
        delete_all_double_link_node(pDLinkNode);  
    }  

    （4）在双向链表中查找数据
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    DOUBLE_LINK_NODE* find_data_in_double_link(const DOUBLE_LINK_NODE* pDLinkNode, int data)  
    {  
        DOUBLE_LINK_NODE* pNode = NULL;  
        if(NULL == pDLinkNode)  
            return NULL;  
      
        pNode = (DOUBLE_LINK_NODE*)pDLinkNode;  
        while(NULL != pNode){  
            if(data == pNode->data)  
                return pNode;  
            pNode = pNode ->next;  
        }  
          
        return NULL;  
    }  

    （5）双向链表中插入数据
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    STATUS insert_data_into_double_link(DOUBLE_LINK_NODE** ppDLinkNode, int data)  
    {  
        DOUBLE_LINK_NODE* pNode;  
        DOUBLE_LINK_NODE* pIndex;  
      
        if(NULL == ppDLinkNode)  
            return FALSE;  
      
        if(NULL == *ppDLinkNode){  
            pNode = create_double_link_node(data);  
            assert(NULL != pNode);  
            *ppDLinkNode = pNode;  
            (*ppDLinkNode)->prev = (*ppDLinkNode)->next = NULL;  
            return TRUE;  
        }  
      
        if(NULL != find_data_in_double_link(*ppDLinkNode, data))  
            return FALSE;  
      
        pNode = create_double_link_node(data);  
        assert(NULL != pNode);  
      
        pIndex = *ppDLinkNode;  
        while(NULL != pIndex->next)  
            pIndex = pIndex->next;  
      
        pNode->prev = pIndex;  
        pNode->next = pIndex->next;  
        pIndex->next = pNode;  
        return TRUE;  
    }  

    （6）双向链表中删除数据
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    STATUS delete_data_from_double_link(DOUBLE_LINK_NODE** ppDLinkNode, int data)  
    {  
        DOUBLE_LINK_NODE* pNode;  
        if(NULL == ppDLinkNode || NULL == *ppDLinkNode)  
            return FALSE;  
      
        pNode = find_data_in_double_link(*ppDLinkNode, data);  
        if(NULL == pNode)  
            return FALSE;  
      
        if(pNode == *ppDLinkNode){  
            if(NULL == (*ppDLinkNode)->next){  
                *ppDLinkNode = NULL;  
            }else{  
                *ppDLinkNode = pNode->next;  
                (*ppDLinkNode)->prev = NULL;  
            }  
      
        }else{  
            if(pNode->next)  
                pNode->next->prev = pNode->prev;  
            pNode->prev->next = pNode->next;  
        }  
      
        free(pNode);  
        return TRUE;  
    }  

    （7）统计双向链表中数据的个数
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    int count_number_in_double_link(const DOUBLE_LINK_NODE* pDLinkNode)  
    {  
        int count = 0;  
        DOUBLE_LINK_NODE* pNode = (DOUBLE_LINK_NODE*)pDLinkNode;  
      
        while(NULL != pNode){  
            count ++;  
            pNode = pNode->next;  
        }  
        return count;  
    }  

    （8）打印双向链表中数据
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    void print_double_link_node(const DOUBLE_LINK_NODE* pDLinkNode)  
    {  
        DOUBLE_LINK_NODE* pNode = (DOUBLE_LINK_NODE*)pDLinkNode;  
      
        while(NULL != pNode){  
            printf("%d\n", pNode->data);  
            pNode = pNode ->next;  
        }  
    }  

    注意：

        今天我们讨论的双向链表是非循环的，大家可以考虑一下如果改成循环双向链表，应该怎么写？如果是有序的循环双向链表，又该怎么写？