c语言链表建立的问题。。。求人来解答

Question

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
typedef struct student
{int number;
struct student *next;
} NODE;
typedef struct student node;
typedef node *link;
link creatlist()
{
    link head,p,q;
    int a;
    char ch;
    head=(link)malloc(sizeof(struct student));
    p=head;
    printf("请输入相关学号：（以？结尾）/n"); 
    while(ch!='?')
    {q=(link)malloc(sizeof(struct student));
    scanf("%d",&a);
    q->number=a;
    p->next=q;
    p=q;
    ch=getchar();
    }
    p->next=NULL; 
    return(head);
}
link add(link head,int a)
{int i,m; char ch; link ptr;
for(i=0;i<a;i++)
head=head->next;
printf("请输入要插入的学号（以？结尾）：");
while(ch!='?')
{scanf("%d",&m);
ptr=(link)malloc(sizeof(struct student));
ptr->number=m;
ptr->next=head->next;
head->next=ptr;
head=ptr; 
ch=getchar();
return 0;
 } 
 } 
 void print(link head)
 {head=head->next;
 while(head!=NULL)
 {printf("%5d",head->number);
 head=head->next;
  } 
  printf("\n") ;
 }
int main()
{link a;  int n;
a=creatlist();
print(a);
printf("请输入要插到第几项的项数：");
scanf("%d",n);
add(a,n);
printf("ok!");
print(a);
return 0;
}

当调用add的函数时显示停止工作，这段代码是为了建立一个链表和插入链表的实现。。求大神解答。。
ps:觉得麻烦的话不用改正，告诉我为什么会出现这种情况就行了。
在此拜谢orz

Answer 1

1.你的main函数里的scanf少了个&
2.然后我接着看了你的creatlist函数，你这个输入必须是输入一个数按一下回车，最后输入的数还必须加上？再按回车才行

 #include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
typedef struct student
{
    int number;
    struct student *next;
} NODE;
typedef struct student node;
typedef node *link;
link creatlist()
{
    link head, p, q;
    int a;
    char ch = ' ';
    head = (link)malloc(sizeof(struct student));
    p = head;
    printf("请输入相关学号：（以？结尾）/n");
    while (ch != '?')
    {
        q = (link)malloc(sizeof(struct student));
        scanf("%d", &a);
        q->number = a;
        p->next = q;
        p = q;
        ch = getchar();
    }
    p->next = NULL;
    return(head);
}
link add(link head, int a)
{
    int i, m; char ch = ' '; link ptr;
    for (i = 0; i<a; i++)
        head = head->next;
    printf("请输入要插入的学号（以？结尾）：");
    while (ch != '?')
    {
        scanf("%d", &m);
        ptr = (link)malloc(sizeof(struct student));
        ptr->number = m;
        ptr->next = head->next;
        head->next = ptr;
        head = ptr;
        ch = getchar();
        return 0;
    }
}
void print(link head)
{
    head = head->next;
    while (head != NULL)
    {
        printf("%5d", head->number);
        head = head->next;
    }
    printf("\n");
}
int main()
{
    link a;  int n;
    a = creatlist();
    print(a);
    printf("请输入要插到第几项的项数：");
    scanf("%d", &n);
    add(a, n);
    printf("ok!");
    print(a);
    return 0;
}