将一个链表按逆序排列，即将链头当链尾，链尾当链头。

源程序：

#include <stdio.h>
#include <malloc.h>
#define LEN sizeof(struct student)
struct student
{
 int num;
 struct student* next;
};

int n;

struct student * creat(void)
{
 //struct student* p1,*p2,*head;
 struct student * p1;
 struct student * p2;
 struct student * head;
 p1=p2=(struct student *)malloc(LEN);
 head=NULL;
 n=0;
 printf("请输入学生的学号（输入学号0结束）：\n");
 scanf("%d",&p1->num);
 while(p1->num!=0)
 {
  n=n+1;
  if(n==1)
   head=p1;
  else
   p2->next=p1;
  p2=p1;
  printf("请输入学生的学号（输入学号0结束）：\n");
  p1=(struct student*)malloc(LEN);
  scanf("%d",&p1->num);
 }
 p2->next=NULL;
 return (head);
}

struct student *nixu(struct student * head)
{
 struct student *s,*t;
 s=head;
 head=NULL;
 while(s)
 {
  t=s;
  s=s->next;
  t->next=head;
  head=t;
 }
 return head;
}

void print(struct student* head,int n)
{
 struct student* p1,*p2,*p3;
 p1=head;
 while(p1!=NULL)
 {
  printf("%d\n",p1->num);
  p1=p1->next;
 }
}

int main()
{
 struct student* head;
 head=creat();
 print(head,n);
 head=nixu(head);
 printf("nixuhou:\n");
 print(head,n);
}