求大家帮我看看这段程序哪里错了。程序有些长，不过都是最基本的知识。谭浩强的C语言教程我们还没学完呢。。谢谢了！！！
程序的用途是输入学生学号，姓名，分数，并按照学号顺序排列。而且还可以随时对链表进行修改。
#include<stdio.h>
#include<malloc.h>
#include<string.h>
#define NULL 0
struct student
    {
        int num;
        char name[20];
        float score;
        struct student *next;
    };
int n=0;                                           //用来计算一共多少人
void main()
{
    struct student* get();
    struct student* insert(struct student *);
    struct student* del(struct student *);
    void print(struct student *);
    void paixu(struct student *);
    struct student *head;
    char t;
    int temp;
    head=get();
    paixu(*head);
    printf("number    name                score\n");
    print(head);
change:printf("<是否需要修改数据y/n>");
    scanf("%c",&t);
    if(t=='y')
    {
        printf("请选择修改的种类:\n1：插入新的数据  2：删除已有数据  3：放弃修改\n");
        scanf("%d",&temp);
        if(temp==1)
            head=insert(head);
        else if(temp==2)
            head=del(head);
        goto change;
    }
    printf("number    name                score\n");
    print(head);
}
struct student *get()
{
    struct student *head,*p1,*p2;
    head=p1=p2=(struct student *)malloc(sizeof(struct student));
    printf("如需结束，请在输入学号时输入:0\n");
    do
    {        
        p2=p1;
        printf("请输入学号：");
        scanf("%d",&p2->num);
        if(p2->num==0)
            goto loop;
        printf("请输入姓名：");
        scanf("%s",p2->name);
        printf("请输入分数：");
        scanf("%f",&p2->score);
        n++;
        p1=(struct student *)malloc(sizeof(struct student));
loop:    p2->next=p1;
    }
    while(p2->num!=0);
    p2->next=NULL;
    return(head);
}
struct student *del(struct student *head)
{
    struct student *p=head;
    int temp;
    printf("请输入需要删除人的学号:");
    scanf("%d",&temp);
    while(p->next!=NULL)
    {
        if(temp==p->num)
            break;
        else
        p=p->next;
    }
    if(temp==p->num)
    {
        if(p==head)                              //删除第一个
            head=head->next;
        else if(p->next==NULL)                   //删除最后一个
            (--p)->next=NULL;
        else
            (--p)->next=(++(++p));
        n--;
    }
    else
        printf("输入的学号有误！");
    return(head);
}
struct student *insert(struct student *head)
{
    struct student *p=(struct student *)malloc(sizeof(struct student));
    struct student *p1=head,p2;
    printf("请输入学号：");
    scanf("%d",&p->num);
    printf("请输入姓名：");
    scanf("%s",p->name);
    printf("请输入分数：");
    scanf("%f",&p->score);
    n++;
    if(p->num<head->num)               //插入的在链表头部
    {
        p-next=head;
        head=p;
    }
    while(p->num>p1->num)
    {
        p2=p1;
        p1=p1->next;
    }
    if(p1->next==NULL)                //插入的在链表尾部
    {
        p1-next=p;
        p->next=NULL;
    }
    else
    {
        p2->next=p;
        p->next=p1;
    }
    return(head);
}
void print(struct student *head)
{
    while(head->next!=NULL)
    {
        printf("%-10d%-20s%-10.1f\n",head->num,head->name,head->score);
        head=head->next;
    }
}
void paixu(struct student *head)               //学号从小到大排
{
    char mingzi[20];
    int xuehao;
    float fenshu;
    struct student *p1,*p2;
    p1=head;
    for(;p1->next!=NULL;p1=p1->next)
        for(p2=p1->next;p2->next!=NULL;p2=p2->next)
            if(p1->num>p2->num)
            {
                strcmp(mingzi,p1->name);
                strcmp(p1->name,p2->name);
                strcmp(p2->name,mingzi);
                xuehao=p1->num;
                p1->num=p2->num;
                p2->num=xuehao;
                fenshu=p1->score;
                p1->score=p2->score;
                p1->score=fenshu;
            }
}
如果可以长期进行辅导，请加我QQ；274862826，价格好商量。