2023年6题--读取存储道路集合信息

#include <stdio.h>
#include <stdlib.h>//动态存储分配函数,eg:malloc


typedef struct Point//每条道路中有多个点
{
    float x,y;
    struct Point *next;
}Point;

typedef struct RoadSegment//道路结构体
{
    int ID;
    int num;
    Point *pts; //类似于邻接表，存储“点链表”的头指针
    struct RoadSegment *next;
}



int main()
{    

    //利用带头节点的链表存储道路
    RoadSegment *head,*tail,*t;
    //初始化道路单链表
    head = (RoadSegment*)malloc(sizeof(RoadSegment));
    head->next = NULL;
    tail = head;


    //打开文件
    int n=0,id;
    FILE *fp = fopen("D:\\小个泡he\\road.text","r");
    if(fp == NULL)
    {
        printf("The file cannot open!\n");
        return 1;
    }

    //每一趟while循环会实例化好一个道路节点，连接起来
    while(!feof(fp))//代表文件没有读到末尾
    {
        //实例化一个道路结构体，尾插法插入道路链表
        RoadSegment *rs = (RoadSegment*)malloc(sizeof(RoadSegment));
        rs->next = tail->next;
        tail->next = rs;
        tail = rs;

        fscanf(fp,"%d,%d\n",&id,&n);//id和num从文件中输入
        rs->num = n;
        rs->ID = id;
        //利用链表存储道路，初始化点链表
        rs->pts = (Point*)malloc(sizeof(Point));//RoadSegment结构体中存储着点链表的头节点
        rs->pts->next = NULL;//重点看下这句话，rs是一个道路结构体类型的指针变量
        
        //s1.x,p1是指向s1指针
        //(*&s1).x==(*p1).x==p1->x
        //rs->pts   ->是一个地址指向运算符，指针变量->成员名
        //(*rs).pts   . 是一个成员运算符，结构体变量.成员名


        //实例化一个点指针
        Point* p;
        p = rs->pts;//指向点链表头节点
        //尾插法建立点链表
        for(int i =0;i<n;i++)
        {
        Point* pt = (Point*)malloc(sizeof(Point));//pt紧接在p后
        fscanf(fp,"%f,%f\n",&pt->x,&pt->y);
        pt->next = p->next;
        p-next = pt;
        p = pt;    
        }
    }
    fclose(fp);//关闭文件
   

    //输入ID为2的路段的坐标
    t = head->next;//
    while(t!=NULL)
    {
        if(t->ID==2)
        {
            printf("&d,%d\n",t-ID,t->num);
            Point *p = t->pts->next;
            while(p!=NULL)
            {
                printf("%f,%f\n",p->x,p->y);
                p=p->next
            }
            break;
        }
        
        t=t->next;
    }
}