程序代码：

typedef struct Student
{
    char    num[15];
    char    name[10];
    char    dorm[10];
    char    major[20];
    char    tel[12];
}ST;

typedef struct ListElmt_
{
    void    *data;   //单链表数据域
    struct ListElmt_    *next;
}ListElmt;

typedef struct List_
{
    int        size;;
    ListElmt    *head;
    ListElmt    *tail;
}List
//插入函数
int        list_insert_next(List *list,ListElmt *element,const void *data){
   
        ListElmt        *new_element;

        /*Allocate storage for element */
        if ((new_element = (ListElmt *)malloc(sizeof(ListElmt))) == NULL)        return  -1;

        /* Insert the element to the list */
        new_element->data = (void *)data;
        if (element == NULL)    {//若element为NULL,则新元素插入链表头部

                if (list_size(list) == 0)    list->tail = new_element;

                new_element->next = list->head;
                list->head = new_element;

                }
        else{
                if (element->next == NULL)        list->tail = new_element;

                new_element->next = element->next;
                element->next = new_element;
        }

        list->size++;
        return 0;
}
我通过下面的插入方式插入，但是head和tail指向的都是最后一个插入的元素。
    struct Student        *stu;
    ListElmt            *p;
    char                yes_no = '\0';

    if ((stu = (struct Student *)malloc(sizeof(struct Student))) == NULL)        return  -1;

    do
    {
        printf("学号:");
        scanf("%s",&stu->num);
        printf("姓名:");
        scanf("%s",&stu->name);
        printf("宿舍:");
        scanf("%s",&stu->dorm);
        printf("专业:");
        scanf("%s",&stu->major);
        printf("联系方式:");
        scanf("%s",&stu->tel);
        p = list->tail;
        if (list_insert_next(list,p,(const void *)stu) == 0){
           
            printf("添加成功,还要继续吗(Y/N)?");
            getchar();
            scanf("%c",&yes_no);
           
        }else{
            printf("添加失败，请重试!");
            system("pause");
            yes_no = 'y';
        }       

    } while (yes_no == 'y' || yes_no == 'Y');

由于先前的一个号找不到了，又重新创了个，就20分，我都给了，希望各位大神能帮帮忙，十分感谢！！