tomlplusplus/examples/toml_to_json_transcoder.cpp

#include <iostream>
#include <fstream>
#include <toml++/toml.h>
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#endif
using namespace std::string_view_literals;

int main(int argc, char** argv)
{
	#ifdef _WIN32
	SetConsoleOutputCP(65001); //UTF-8 console output
	#endif

	//read from a file
	if (argc > 1)
	{
		auto path = std::string{ argv[1] };
		auto file = std::ifstream{ path };
		if (!file)
		{
			std::cerr << "The file '"sv << path << "' could not be opened for reading."sv << std::endl;
			return -1;
		}

		try
		{
			const auto table = toml::parse(file, std::move(path));
			std::cout << toml::json_formatter{ table } << std::endl;
		}
		catch (const toml::parse_error& err)
		{
			std::cerr << "Error parsing file:\n"sv << err << std::endl;

			return 1;
		}
	}

	//read directly from stdin
	else 
	{
		try
		{
			const auto table = toml::parse(std::cin);
			std::cout << toml::json_formatter{ table } << std::endl;
		}
		catch (const toml::parse_error& err)
		{
			std::cerr << "Error parsing stdin:\n"sv << err << std::endl;

			return 1;
		}
	}

	return 0;
}