我想编写一个自定义类DateAndTime，以简化项目中与日期有关的工作。问题是我不能正确地比较日期或者我有一个转换日期的问题。

我的目标是:

1. 将DateAndTime创建为当前日期/li>

请帮帮我:）

这是我的密码

#include <iostream>
#include <sstream>
#include <ctime>

using namespace std;

class DateAndTime
{
    private:
        const std::string dateTemplate = "%Y-%m-%d %H:%M";
    public:
        int year;
        int month;
        int day;
        time_t fullDate;
    public:
        DateAndTime(std::string dataString)
        {
             struct tm tm;
             strptime(dataString.c_str(), dateTemplate.c_str() ,&tm);
             year = 1900 + tm.tm_year;
             month = 1 + tm.tm_mon;
             day = tm.tm_mday;
             fullDate = mktime(&tm);
             cout << "Date from string: " << ctime(&fullDate) << endl;
        }
        DateAndTime()
        {
             time_t currentDate;
             struct tm * localDate;
             time (&currentDate);
             localDate = localtime (&currentDate);
             fullDate = currentDate;
             year = 1900 + localDate->tm_year;
             month = 1+ localDate->tm_mon;
             day = localDate->tm_mday;
             cout << "Current date: " << ctime(&fullDate) << endl;
        }
    public:
        std::string toString()
        {
            return std::to_string(year) + "-" + std::to_string(month) + "-" + std::to_string(day); 
        }
        int diffDays(DateAndTime data)
        {
           return difftime(data.fullDate, this->fullDate) / 86400;//devide by 1d in seconds
        }
};

int main()
{
    //Now
    DateAndTime d1;
    cout<< d1.year << endl;
    cout<< d1.month << endl;
    cout<< d1.day << endl;
    cout << d1.toString() << endl << endl;
         
    //Other
    string d = "2021-14-01 14:17:33";
    DateAndTime d2(d);
    cout<< d2.year << endl;
    cout<< d2.month << endl;
    cout<< d2.day << endl;
    cout<< d2.toString();
    
    cout << endl;
    
    cout << "Diff days: " << d1.diffDays(d2);
    
    return 0;
}

结果:

Current date: Thu Jan 14 14:40:18 2021
2021
1
14
2021-1-14
Date from string: Wed Mar 28 07:53:20 -26461971
2021
-314878271
32767
2021--314878271-32767
Diff days: -2147483648*