//
// This is example code from Chapter 10.4 "Opening a file" of
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//

#include <iostream>
#include <fstream>
#include <string>
#include "std_lib_facilities.h"

using namespace std;

//------------------------------------------------------------------------------

struct Point
{
   int x;
   int y;

   friend istream& operator>>(istream& ist, Point& p)
      {
         char a,b,c;

         if ((ist >> a >> p.x >> b >> p.y >> c) && !(a == '(' && b == ',' && c == ')'))
            throw runtime_error("Invalid format");

         return ist;
      }

   friend ostream& operator<<(ostream& ost, const Point& p)
      {
         return ost << '(' << p.x << ',' << p.y << ')' << endl;
      }
};

//------------------------------------------------------------------------------

int main()
   try
      {
         cout << "Please enter name of output file: ";
         string name;
         cin >> name;
         ofstream ost(name.c_str());    // ost is an output stream for a file named name
         if (!ost) error("can't open output file ",name);

         vector<Point> points;

         for (int i = 0; i < 10; ++i) {
            Point p = {i, i*i};
            points.push_back(p);
         }

         for (Point p: points)
            ost << '(' << p.x << ',' << p.y << ")\n";
      }
   catch (exception& e) {
      cerr << "error: " << e.what() << '\n'; 
      return 1;
   }
   catch (...) {
      cerr << "Oops: unknown exception!\n"; 
      return 2;
   };

//------------------------------------------------------------------------------

void fill_from_file(vector<Point>& points, string& name)
{
//    ifstream ist(name.c_str());    // open file for reading
   ifstream ist{name};    // open file for reading
   if (!ist) error("can't open input file ",name);
   // ... use ist ...
   // the file is implicitly closed when we leave the function
}

//------------------------------------------------------------------------------