对了，还有个问题。您的add函数写的很巧妙，但我改了我的add函数，为什么还是不对呢？我感觉我的思路应该也能成功才对啊？
下面是我改的add，希望能告诉我到底哪里写得不合适才会出错的？

struct student *add(struct student*head,struct student *stu1)
{
    struct student *p1,*p0,*p2;
    p1=head;
    p0=(struct student*)malloc(LEN);
    p0=stu1;
    p0->next=NULL;
    if(head==NULL)
    {
        head=p0;
       
       
    }
    else
    {
        while ((p1!=NULL)&&(p0->num>p1->num))
    {
        p2=p1;
        p1=p1->next;
    }
                                                                                                        
        if(p0->num<=p1->num )
        {
            if(p1==head)
            {
                head=p0;
                p0->next=p1;       
            }
            else
            {
                p2->next=p0;
                p0->next=p1;
           
            }
           
        }
        else
        {
            p1->next=p0;
           
        }
   
   
    }
         printf("\nDelete No: %d succeed!\n", p0->num);
            n = n+1;
    return(head);
}

希望还有好人出来帮我看看上面的代码哪里错了？

谢谢每位私信我的 人儿！

struct student *add(struct student*head,struct student *stu1)
{
    struct student *p1,*p0,*p2;
    p1=head;
    //p0=(struct student*)malloc(LEN);
    p0=stu1;
    if(p0->num==0) return head;        //这里我加上一句
    p0->next=NULL;
    if(head==NULL)
    {
        head=p0;
      
      
    }
    else
    {
        while ((p1!=NULL)&&(p0->num>p1->num))
        {
            p2=p1;
            p1=p1->next;
           }   
       /*其实你自己写的不比别人差多少，只是看似考虑全面，实则多虑。下面的你自己仔细思考下*/                                                                                                
       // if(p0->num<=p1->num )
       // {
            if(p1==head)
            {
                head=p0;
                p0->next=p1;      
            }
            else
            {
                p2->next=p0;
                p0->next=p1;
           
            }
           
       // }
       // else
       // {
         //   p1->next=p0;
           
       // }
   
   
    }
         printf("\nDelete No: %d succeed!\n", p0->num);
            n = n+1;
    return(head);
}

int main()
{
    struct student *q,*stu,stu2,*p;
    int x;
    int a;
    stu=creat();
    q=stu;
    //p=&stu2;
    print(q);
    printf("How do you want to do:del='1',add='2'\n");
      
        scanf("%d",&a);
        if(a==1)
        {
        do
        {
      
        printf("please input the num of you want to deleat: ");
        scanf("%d",&x);
        q=del(q,x);
        if(q==NULL)
        {
           
            break;
        }
        print(q);
      
      
        }while(x!=0);
        }
        else
        {
            do
            {
                p=(struct student*)malloc(LEN);
                printf("\nplease input the num  you want to insert: ");
                scanf("%d",&(p->num));
                printf("please input the score  you want to insert: ");
                scanf("%f",&(p->score));
               
                q=add(q,p);
                if(q==NULL)
                 {
           
                    break;
                }
                print(q);
            }while(p->num!=0);
           
        }
   
   
            printf("\n\n");
        system("pause");
}

感觉考虑多了反而冗余了，最后结果都错了！真是太感谢您了，其实我看完您改的代码想到
其实这个程序只是用指针来指向链表的各个结点，再插入新节点时，并没有真正的改变原结点
的其它数据，所以只要把插入的结点和相邻的结点之间的关系（及地址）写正确就醒了，其它的
考虑多了都是错！
再次感谢您，以及回复帮助我的所有好人！