1 #include<stdio.h>
  2 #include<stdlib.h>
  3 #include<malloc.h>
  4

  5 typedef struct students{
  6         int a;
  7         struct students *n;
  8 }stu;
  9


 10 typedef struct list{

 11         stu *ll;

 12 }List;

 13


 14 stu *add(stu *head,int number);

 15


 16 int main()

 17 {

 18         stu *head;

 19         //head=NULL;
 20         List *ls;

 21         ls->ll=NULL;

 22         int number=1;

 23         while(number!=0)

 24         {

 25                 scanf("%d",&number);

 26                 head=add(ls,number);

 27         }

 28         while(head->n)

 29         {

 30                 printf("------------\n%d\n",head->a);

 31                 head=head->n;

 32         }

 33         return 0;

 34 }

 35


 36


 37 int add(List *ls,int number)

 38 {

 39         stu *q,*l;

 40         q=(stu*)malloc(sizeof(stu));

 41         q->a=number;

 42         q->n=NULL;

 43         l=ls->ll;

 44         if(l)

 45         {

 46                 while(l->n)

 47                 {

 48                         l=l->n;

 49                 }

 50                 l->n=q;

 51         }else{

 52                 ls->ll=q;

 53         }

 54 }

lockeroots@lockeroots-1215T ~ $ g++ 506b.c
506b.c: In function ‘int main()’:
506b.c:26:21: error: cannot convert ‘List* {aka list*}’ to ‘stu* {aka students*}’ for argument ‘1’ to ‘stu* add(stu*, int)’
   head=add(ls,number);
                     ^

出现这样的提示  求大神指点一二