#include <stdio.h>
#define NULL 0
struct student
{
    char name[20];
    char sex;
    int num, year;
    struct student *next;
};
struct student *input(struct student *head)
{
    int n = 0;
    struct student *p1, *p2;
    p1 = p2 = (struct student*) malloc (sizeof(struct student));
    printf ("please enter information:");
    scanf ("%s%d%c%d", p1->name, &p1->num, &p1->sex, &p1->year);
    while (p1->num > 0)
    {
        n++;
        if (n == 1)
        {
            head = p1;
        }
        else
        {
            p2->next = p1;
            p2 = p1;
        }
        p1 = (struct student*) malloc (sizeof(struct student));
        scanf ("%s%d%c%d", p1->name, &p1->num, &p1->sex, &p1->year);
    }
    p2->next = NULL;
    return (head);
}
void output (struct student *head)
{
    struct student *p;
    p = head;
    while (p != NULL)
    {
        printf ("%s     %d     %c     %d", p->name, p->num, p->sex, p->year);
        p = p->next;
    }
}
void main ()
{
    struct student *head;
    head = NULL;
    head = input (head);
    output (head);
}

  if (n == 1)
        {
            head = p1;
            p2=p1;                //在这加个，否则的化，你的程序在第一个结点后面就连不起来！
        }

#include <stdio.h>
#include <malloc.h>
#define NULL 0
struct student
{
    char name[20];
    char sex[10];
    int num, year;
    struct student *next;
};
struct student *input(struct student *head)
{
    int n = 0;
    struct student *p1, *p2;
    p1 = p2 = (struct student*) malloc (sizeof(struct student));
    printf ("please enter information:name,num,sex,year");
    printf("\n");
    scanf ("%s %d %s %d", p1->name, &p1->num, p1->sex, &p1->year);
    while (p1->num > 0)
    {
        n++;
        if (n == 1)
        {
            head = p1;
        }
        else
        {
            p2->next = p1;
            p2 = p1;
        }
        p1 = (struct student*) malloc (sizeof(struct student));
        printf ("please enter information:name,num,sex,year");
        printf("\n");
        scanf ("%s %d %s %d", p1->name, &p1->num, p1->sex, &p1->year);
    }
    p2->next=p1;
    p2=p1;
    p2->next = NULL;
    return (head);
}
void output (struct student *head)
{
    struct student *p;
    p = head;
    printf("information is:");
    while (p ->next!= NULL)
    {
        printf("\n");
        printf ("%s     %d     %s     %d", p->name, p->num, p->sex, p->year);
        p = p->next;
        printf("\n");
    }
}
void main ()
{
    struct student *head;
    head = NULL;
    head = input (head);
    output (head);
}
我给你改了一下，不过还有一些不足之处，我希望你能尽量完善它。
你说的那个问题，我看了一下，你没有把最后一个和倒数第二个连起来，所以应在while循环外面再加点东西，使他们连起来。

[ 本帖最后由 流行语 于 2010-5-29 16:55 编辑 ]