How to convert ISO week number to US week number in C++

Question

I am using boost gregorian library for date calculation in c++ boost gregorian returns week number in ISO format but I want week number in US format.

how I can get week number in US format.

please see link https://planetcalc.com/1252/

e.g.

#include <boost/date_time/gregorian/gregorian.hpp>

int main(int argc, char* argv[])
{
    boost::gregorian::date myday1 = boost::gregorian::from_simple_string("2005-1-1");
    int weekNum1 = myday1.week_number(); //return ISO which is 53 //week 1 as US method
    boost::gregorian::date myday2 = boost::gregorian::from_simple_string("2005-1-2");
    int weekNum2 = myday2.week_number(); //return ISO which is 53 //week 2 as US method
    return 0;
}

Using visual studio 2019 community on windows 10

Answer 1

I find no direct way in C++ or any library which support US method for week number, So I have to use CLR dll and call it from native C++.

//Header file
#pragma once
__declspec(dllexport) int GetWeekNumber(int year, int month, int day);

C++/CLI File

#include "pch.h"
#include "CLRDll.h"

using namespace System;
using namespace System::Globalization;

namespace CLRDll
{
   public ref  class CCalender
   {
        static CultureInfo^ cinfo = gcnew CultureInfo("en-US");
        static Calendar^ cal = cinfo->Calendar;
        // Gets the DTFI properties required by GetWeekOfYear.
        static CalendarWeekRule^ myCWR = cinfo->DateTimeFormat->CalendarWeekRule;
        static DayOfWeek^ myFirstDOW = cinfo->DateTimeFormat->FirstDayOfWeek;

      public:
        int GetWeekNumber(int year, int month, int day);
        // TODO: Add your methods for this class here.
    };
 }

 int CLRDll::CCalender::GetWeekNumber(int year, int month, int day)
 {
     DateTime^ dt = gcnew DateTime(year, month, day);
     return cal->GetWeekOfYear(*dt, *myCWR, *myFirstDOW);
 }

 __declspec(dllexport) int GetWeekNumber(int year, int month, int day)
 {
     CLRDll::CCalender c;
    return c.GetWeekNumber(year, month, day);
 }