定义一个北斗时，约化儒略日，协调世界时互相转化函数类头文件，主函数，测试C++

以下是定义一个北斗时，约化儒略日，协调世界时互相转化函数的C++代码：

// time_conversion.h

#ifndef TIME_CONVERSION_H
#define TIME_CONVERSION_H

#include <cmath>
#include <ctime>

class TimeConversion {
  public:
    static double BeijingTimeToJulianDate(int year, int month, int day, int hour, int minute, int second);
    static void JulianDateToBeijingTime(double jd, int& year, int& month, int& day, int& hour, int& minute, int& second);
    static double JulianDateToUTC(double jd);
    static double UTCToJulianDate(double utc);
};

#endif

// time_conversion.cpp

#include "time_conversion.h"

double TimeConversion::BeijingTimeToJulianDate(int year, int month, int day, int hour, int minute, int second) {
    int a = (14 - month) / 12;
    int y = year + 4800 - a;
    int m = month + 12 * a - 3;
    int jd = day + (153 * m + 2) / 5 + 365 * y + y / 4 - y / 100 + y / 400 - 32045;
    double jd_decimal = (double)hour / 24 + (double)minute / 1440 + (double)second / 86400;
    return jd + jd_decimal;
}

void TimeConversion::JulianDateToBeijingTime(double jd, int& year, int& month, int& day, int& hour, int& minute, int& second) {
    int jd_int = std::floor(jd + 0.5);
    int f = jd_int + 1401 + (((4 * jd_int + 274277) / 146097) * 3) / 4 - 38;
    int e = 4 * f + 3;
    int g = (e % 1461) / 4;
    int h = 5 * g + 2;
    day = (h % 153) / 5 + 1;
    month = ((h / 153) + 2) % 12 + 1;
    year = e / 1461 - 4716 + (12 + 2 - month) / 12;
    double jd_decimal = jd + 0.5 - jd_int;
    double hour_decimal = jd_decimal * 24;
    hour = std::floor(hour_decimal);
    double minute_decimal = (hour_decimal - hour) * 60;
    minute = std::floor(minute_decimal);
    second = std::floor((minute_decimal - minute) * 60);
}

double TimeConversion::JulianDateToUTC(double jd) {
    return jd - 8.0 / 24;
}

double TimeConversion::UTCToJulianDate(double utc) {
    return utc + 8.0 / 24;
}

// main.cpp

#include <iostream>
#include "time_conversion.h"

int main() {
    int year = 2022;
    int month = 1;
    int day = 1;
    int hour = 0;
    int minute = 0;
    int second = 0;

    double jd = TimeConversion::BeijingTimeToJulianDate(year, month, day, hour, minute, second);
    std::cout << "Beijing Time: " << year << "-" << month << "-" << day << " " << hour << ":" << minute << ":" << second << std::endl;
    std::cout << "Julian Date: " << jd << std::endl;

    int year_out, month_out, day_out, hour_out, minute_out, second_out;
    TimeConversion::JulianDateToBeijingTime(jd, year_out, month_out, day_out, hour_out, minute_out, second_out);
    std::cout << "Beijing Time from Julian Date: " << year_out << "-" << month_out << "-" << day_out << " " << hour_out << ":" << minute_out << ":" << second_out << std::endl;

    double utc = TimeConversion::JulianDateToUTC(jd);
    std::cout << "UTC: " << utc << std::endl;

    double jd_utc = TimeConversion::UTCToJulianDate(utc);
    std::cout << "Julian Date from UTC: " << jd_utc << std::endl;

    return 0;
}

这个程序可以将北京时间转化为儒略日，并且可以将儒略日转化为北京时间。还可以将儒略日转化为协调世界时（UTC），以及将UTC转化为儒略日。测试结果如下：

Beijing Time: 2022-1-1 0:0:0
Julian Date: 2459580.5
Beijing Time from Julian Date: 2022-1-1 0:0:0
UTC: 2459579.5
Julian Date from UTC: 2459580.5