#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <stdexcept>

struct format_error : std::runtime_error
{
  format_error() : std::runtime_error("Invalid Format") {}
};

int main(int argc, char** argv)
{
  {
    // close file when printer goes out of scope
    std::ofstream printer("test.txt");

    if (!printer.is_open())
    {
      std::cerr << "Error opening file for writing\n";
      exit(2);
    }

    printer << " 123 456.2 789 \n";
    printer << "987  865.2 \t  432\n";
    printer << "garbage 1234 567\n";
    printer << "666 7777.4 888\n";
  }

  std::ifstream reader("test.txt");

  if (!reader.is_open())
  {
  std::cerr << "Error opening file for reading\n";
  exit(3);
  }

  int i1;
  int i2;
  double d1;
  std::string raw_text;

  while( std::getline(reader, raw_text))
  {
    std::cout << "READ: " << raw_text << std::endl;
    std::istringstream parser(raw_text);

    try
    {
      if (!(parser >> i1))
      {
        throw format_error();
      }
      if (!(parser >> d1))
      {
        throw format_error();
      }
      if (!(parser >> i2))
      {
        throw format_error();
      }
    }
    catch(format_error e)
    {
      std::cerr << "Invalid format for line: " << raw_text << "\n\n";
      continue;
    }

    std::cout << "PARSED: " << i1 << "|" << d1 << "|" << i2 << "\n\n";
  }

  return 0;
}