//7定义一个排序函数
struct student *sort(struct student *h)
{
    int i,j,k;
    struct student *p1,*p3;
    p3=(struct student*)malloc(LEN);
    printf("请选择排序方式1按学号排序2按总分排序\n");
    scanf("%d",&j);getchar();
    if(j==1)
   {  
         
     
     
     
     for(i=0;i<n-1;i++)
     {  p1=head;
         
         
         
         for(k=0;k<n-i-1;k++)
         {
             if(p1->num>p1->next->num)
             {
                 *p3=*p1;
                 *p1=*(p1->next);
                 *(p1->next)=*p3;
             }
             p1=p1->next;
            
         }
     }
                 
                    
}
  
  return(head); }