Simple toy program to set the brightness on my laptop. Mostly for gaining a little exposure to the filesystem library

brightness.cpp

#include <experimental/filesystem>
#include <fstream>
#include <string>

namespace fs = std::experimental::filesystem;
using namespace std::string_literals;

fs::path const get_backlight_dir(std::string const& path)
{
	auto const iterator = fs::directory_iterator{fs::path{path}};
	return iterator->path();
}

int const get_max_brightness(fs::path const& backlight_dir)
{
	auto const max_backlight_path = backlight_dir / "max_brightness"s;

	std::ifstream max_brightness_file{max_backlight_path};

	int max_brightness{};
	max_brightness_file >> max_brightness;
	return max_brightness;
}

void set_brightness(fs::path const& backlight_dir, int const level)
{
	std::ofstream{backlight_dir / "brightness"s} << std::to_string(level);
}

int main(int argc, char* argv[])
{
	auto const percentage = [argc, argv] {
		return (argc == 2) ? std::min(std::stod(argv[1]) / 100.0, 1.0) : 1.0;
	}();
	auto const backlight_dir  = get_backlight_dir("/sys/class/backlight/"s);
	auto const max_brightness = get_max_brightness(backlight_dir);
	set_brightness(backlight_dir, static_cast<int>(max_brightness * percentage));

	return 0;
}