extract data from csv files, C++ (vc++)

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//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64

#include <iostream>
#include <fstream>
#include <filesystem>
#include <regex>
#include <string>

namespace fs = std::experimental::filesystem;

// get the names of all files in the directory with extension .csv
std::vector<std::string> csv_files( const std::string& dir_path = "." )
{
	std::vector<std::string> result;

for( const fs::path& path : fs::directory_iterator(dir_path) )
		if( fs::is_regular_file(path) && path.extension() == ".csv" ) result.push_back( path.string() );

return result;
}

struct data
{
	std::string first_name;
	std::string last_name;
	int weight;
	int age;
};

// extract data from the line; return true if successfully extracted
bool parse_line(const std::string& line, data& d )
{
	static const std::regex csv_re("^([^,]+)\\,([^,]+)\\,\\s*(\\d+)\\s*\\,\\s*(\\d+)\\s*$");

std::smatch match_results;
	if( std::regex_match( line, match_results, csv_re ) )
	{
		d = { match_results[1], match_results[2], std::stoi(match_results[3] ), std::stoi(match_results[4]) };
		return true;
	}

d = {}; // parse failed
	return false;
}

// return all data extracted from a file
std::vector<data> parse_file(const std::string& path)
{
	std::vector<data> result;

std::ifstream file(path);
	std::string line;
	data d;
	while( std::getline(file, line) ) if( parse_line( line, d ) ) result.push_back(d);

return result;
}

int main()
{
	for( const auto& file_name : csv_files() ) // for each .csv file in the current directory
	{
		std::cout << "\nfile name: " << file_name << "\n----------------\n";

// print out the data extracted from the file
		for( const data& d : parse_file(file_name) )
			std::cout << d.first_name << ' ' << d.last_name << ' ' << d.weight << ' ' << d.age << '\n';
	}
    
    std::cout << "\n*** ok ***\n" ;
}

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Compilation time: 12,68 sec, absolute running time: 1,28 sec, absolute service time: 13,97 sec