#include<stdio.h>
#include<malloc.h>
#define NULL 0
struct student{
    int   num;
    float score;
    struct student *next;
};
main()
{
    void print(struct student *head);
    struct student *del(struct student *head,int num);
    struct student *insert(struct student *head,struct student *stu);
    struct student *head,*p1,*p2,*stu;
    int num,n=0;
    printf("建立一个动态链表，并输出.\n");
    p1=p2=(struct student *)malloc(sizeof(struct student));
    head=NULL;
    printf("Enter the num,score:");
    scanf("%d%f",&p1->num,&p1->score);
    while(p1->num!=0)
    {
        n++;
        if(n==1)
            head=p1;
        else
            p2=p1;
        p1=(struct student *)malloc(sizeof(struct student));
        p2->next=p1;
        printf("Enter the num,score:");
        scanf("%d%f",&p1->num,&p1->score);
    }
    p2->next=NULL;
    print(head);
    printf("输入要删除的学生学号:");
    scanf("%d",&num);
    while(num!=0)
    {
        head=del(head,num);
        print(head);
        printf("输入要删除的学生学号:");
        scanf("%d",&num);
    }
    printf("插入一个节点:\n");
    stu=(struct student *)malloc(sizeof(struct student));
    printf("Enter num,score:");
    scanf("%d%f",&stu->num,&stu->score);
    while(stu->num!=0)
    {
        head=insert(head,stu);
        print(head);
        printf("插入一个节点:\n");
        stu=(struct student *)malloc(sizeof(struct student));
        printf("Enter num,score:");
        scanf("%d%f",&stu->num,&stu->score);
    }
    return 0;
}
void print(struct student *head)
{
    struct student *p;
    int n=0;
    p=head;
    printf("These records are:\n");
    if(p==NULL)return;
        while(p!=NULL)
        {
            n++;
            printf("NO.%d: %.2f\n",p->num,p->score);
            p=p->next;
        }
        printf("These are %d dates!\n",n);
}
struct student *del(struct student *head,int num)
{
    struct student *p1,*p2;
    p1=p2=head;
    if(p1==NULL)return head;
    while(p1->num!=num)
    {
        if(p1->next==NULL)return head;
        else
        {
        p2=p1;
        p1=p1->next;
        }
    }
    if(p1->num==num)
    {
        if(p1==head)
        {
            if(p1->next!=NULL)head=p1->next;
            else head=NULL;
        }
        else
            p2->next=p1->next;
    }
    else
        printf("%d not been found!\n",num);
    return head;
}
struct student *insert(struct student *head,struct student *stu)
{
    struct student *p0,*p1,*p2;
    p1=head;
    p0=stu;
    if(head==NULL)
    {
        head=p0;
        p0->next=NULL;
    }
    else
        {
        while((p0->num>p1->num)&&(p1->next!=NULL))
            {
                p2=p1;
                p1=p1->next;
            }
        if(p0->num<=p1->num)
            {
            if(p1==head)head=p0;
            else p2->next=p0;
            p0->next=p1;
            }
        else
            {
                p1->next=p0;
                p0->next=NULL;
            }
        }
        return head;
}


检查了很多遍，插入函数也没有错，逻辑也没问题，就是不知道为什么输入插入的号码之后就press anykey了