航班管理系统的文件写入读取问题

Question

想写一个飞机管理系统读取数据时发生了错误，但不知道哪里错了，有没有神帮忙看一看，当我第一次写入时貌似没有写入，当我写入完成后，将几个飞机注释了也不能重新读出来。能看看是哪里有错误吗？

用代码块功能插入代码，请勿粘贴截图

#include <iostream>
#include <string.h>
#include <fstream>
#include <iomanip>
#include <stdlib.h>
#include <set>
using namespace std;


string getcompany(char no[10])//通过前两个字母找公司
{
    string company(no);
    company = company.substr(0,2);
    if(company == "CA") return "中国国际航空公司";
    if(company == "CZ") return "中国南方航空公司";
    if(company == "MU") return "中国东方航空公司";
    else return "unkowned";
}


class Flight//航班模块
{
    public:
    char no[10];
    char startplace[10];
    char endpalce[10];
    char schedule[10];
    char starttime[10];
    char endtime[10];
    char airtype[10];
    double price;
    string company;
    Flight(){}
    Flight(char uno[],char ustartplace[], char uendplace[],char uschedule[],char ustarttime[], char uendtime[],char uairtype[], double uprice)
    {
        strcpy(no,uno);
        strcpy(startplace,ustartplace);
        strcpy(endpalce,uendplace);
        strcpy(schedule,uschedule);
        strcpy(starttime,ustarttime);
        strcpy(endtime, uendtime);
        strcpy(airtype,uairtype);
        price = uprice;
        company = getcompany(no);
    }
    void input_information();
    bool operator < (const Flight &f) const{
        return strcmp(f.no,this->no) > 0;
    }
    bool operator > (const Flight &f) const{
        return strcmp(f.no,this->no) < 0;
    }
    
};


int main()
{
    fstream flightinformation("flightinformation.dat", ios::out|ios::binary);//
    set<Flight> flight;            
       Flight flight6;
    Flight newflight;
    set<Flight>::iterator it;
    int n = 0;
    flightinformation.open("flightinformation.dat",ios::in|ios::binary);
    if(!flightinformation)
    {
        cout << "文件打开失败" << endl;
    }
    while(flightinformation)
    {  
        flightinformation.read((char*)&flight6, sizeof(flight6));
        int cc = flightinformation.gcount(); // *** 新添加，判断读字节数是否吻合 
        if(cc == sizeof(Flight))
        {
            cout << flight6.price << endl;
            cout << flight6.no << " " << flight6.startplace << endl;
            flight.insert(flight6);
        }
    }
    flightinformation.close();
    Flight flight1("CA2386","珠海","上海","12367","15:25","15:25","波音737-8",680);
    Flight flight2("CA9988","北京","香港","1234567","19:00","22:00","南飞C919",1600);
    Flight flight3("CZ5685","杭州","重庆","357","18:30","20:35","空客380",568);
    Flight flight4("MU9816","广州","北京","1234567","10:50","13:16","波音787",780);
    Flight flight5("MU9912","新加坡","旧金山","157","12:00","23:30","波音737-8",8768);
    flight.insert(flight1);
    flight.insert(flight2);
    flight.insert(flight3);
    flight.insert(flight4);
    flight.insert(flight5);
    //showmain(flight,flightinformation);
    flightinformation.open("flightinformation.dat", ios::out|ios::binary);
    for(it = flight.begin(); it != flight.end(); it++)//定义前向迭代器遍历输出 
    {
        flightinformation.write((char*)& (*it), sizeof(Flight));
    }
    flightinformation.close();
    return 0;

我的解答思路和尝试过的方法

我希望能先从几个定义的航班中读取数据，然后生成了二进制文件，接着将航班注释掉，我仍能从文件中读取到之前的航班。

Answer 1

• 这有个类似的问题, 你可以参考下: https://ask.csdn.net/questions/7790374