//链表的创建
Link_t *create_link()
{
    Link_t *plink = malloc(sizeof(Link_t));
    if(NULL == plink)
    {
        perror("fail plink");
        return NULL;
    }
    plink->phead = NULL;
    plink->clen = 0;
    return plink;
}

//头插
int push_link_head(Link_t *plink, DataType data)
{
    Link_Node_t *pnode = malloc(sizeof(Link_Node_t));
    if(NULL == pnode)
    {
        perror("fail malloc");
        return -1;
    }
    pnode->data = data;
    pnode->pnext = NULL;

    pnode->pnext = plink->phead;
    plink->phead = pnode;
    plink->clen++;

    return 0;
}

//尾插
int push_link_end(Link_t *plink, DataType data)
{
    Link_Node_t *p = plink->phead;
    if(p == NULL)
    {
        push_link_head(plink, data);
    }
    else
    {
        while(p->pnext != NULL)
        {
            p = p->pnext;
        }
        Link_Node_t *pnode = malloc(sizeof(Link_Node_t));
        if(NULL == pnode)
        {
            perror("fail pnode");
            return -1;
        }
        p->pnext = pnode;
        pnode->pnext = NULL;
        pnode->data = data;
        plink->clen++;
    }
    return 0;
}

//头删
int push_head_pop(Link_t *plink)
{
    Link_Node_t *p = plink->phead;
    if(p == NULL)
    {
        return 0;
    }
    else
    {
        plink->phead = p->pnext;
        free(p);
    }
    plink->clen--;
    return 1;
}

//尾删
int push_end_pop(Link_t *plink)
{
    Link_Node_t *p = plink->phead;
    if(p == NULL)
    {
        return 0;
    }
    else if(p->pnext == NULL)
    {
        push_head_pop(plink);
    }
    else
    {
        while(p->pnext->pnext != NULL)
        {
            p = p->pnext;
        }
        free(p->pnext);
        p->pnext = NULL;
    plink->clen--;
    }
    return 1;
}