Step by Step solution about How to resolve the algorithm Last Friday of each month step by step in the C++ programming language

Both code snippets demonstrate how to find the last Friday in each month of a given year. However, they use different libraries and approaches.

First Code Snippet (Boost Library):

• This code uses the Boost Date and Time Library, which provides a comprehensive set of classes and functions for working with dates and times.
• It creates an array of greg_month enums representing the 12 months of the year.
• It parses a year as an integer from the command-line argument.
• It iterates through the months and uses the last_day_of_the_week_in_month class to calculate the date of the last Friday in each month.
• It prints the calculated dates using the operator<< overload for the date class.

Second Code Snippet (C++20 Library):

• This code uses the C++20 Standard Library, which includes support for time and date manipulation.
• It uses the std::chrono namespace to work with dates and times.
• It iterates through the months of the year from January to December.
• For each month, it calculates the number of days using the last manipulator, which returns the last day of the month.
• It then uses a loop to find the last Friday by decrementing the std::chrono::year_month_day object representing the last day of the month until it encounters a Friday.
• It prints the calculated dates using the operator<< overload for the std::chrono::year_month_day class.

Both code snippets accomplish the task of finding the last Friday in each month of a given year. However, the first snippet relies on an external library, while the second one uses the standard library, which may be more convenient in some cases.

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

int main( int argc , char* argv[ ] ) {
   using namespace boost::gregorian ;

   greg_month months[ ] = { Jan , Feb , Mar , Apr , May , Jun , Jul ,
      Aug , Sep , Oct , Nov , Dec } ;
   greg_year gy = atoi( argv[ 1 ] ) ;
   for ( int i = 0 ; i < 12 ; i++ ) {
      last_day_of_the_week_in_month lwdm ( Friday , months[ i ] ) ;
      date d = lwdm.get_date( gy ) ;
      std::cout << d << std::endl ;
   }
   return 0 ;
}


#include <chrono>
#include <iostream>

int main() {
	std::cout << "The dates of the last Friday in each month of 2023:" << std::endl;

	for ( unsigned int m = 1; m <= 12; ++m ) {
		std::chrono::days days_in_month = std::chrono::sys_days{std::chrono::year{2023}/m/std::chrono::last}
			- std::chrono::sys_days{std::chrono::year{2023}/m/1} + std::chrono::days{1};

		const unsigned int last_day = days_in_month / std::chrono::days{1};
		std::chrono::year_month_day ymd{std::chrono::year{2023}, std::chrono::month{m}, std::chrono::day{last_day}};

		while ( std::chrono::weekday{ymd} != std::chrono::Friday ) {
			ymd = std::chrono::sys_days{ymd} - std::chrono::days{1};
		}

		std::cout << ymd << std::endl;
	}
}