高手帮忙看看我的这段链表删除函数代码哪儿出错了。运行老是出错。

Question

struct student *del(struct student *head,long num1)
{
struct student *p1,*p2;
if(head=NULL)
{
printf("\nlist null!\n");
return(head);
}
p1=head;
while((num1!=p1->num)&&(p1->next!=NULL))
{
p2=p1;
p1=p1->next;
}
if(num1==p1->num)
{
if(p1==head)
head=p1->next;
else
p2->next=p1->next;
printf("delete:%ld\n",num1);
n=n-1;
}
else
printf("%ld not been found!\n",num1);
return(head);
}

Answer 1

if(p1==head)
head=p1->next;
error here；