#include <iostream>
#include <fstream>

using namespace std;

int gcd(int a, int b)
{ while (b != 0)
  { int t = a % b;
    a = b;
    b = t; }
  return a; }

struct fraction
{ int top, bot;

  fraction(int t, int b)
  { top = t;
    bot = b;
    normalise(); }
    
  void normalise()
  { if (bot == 0)
    { cerr << "error: zero denominator\n";     // check added after class
      exit(1); }
    if (bot < 0)                               // negatives added after class
    { bot = - bot;
      top = - top; }
    int g = gcd(top, bot);
    top /= g;
    bot /= g; }

  fraction multiply(const fraction g)
  { return fraction(top * g.top, bot * g.bot); }

  fraction divide(const fraction g)
  { return fraction(top * g.bot, bot * g.top); }

  fraction add(const fraction g)
  { return fraction(top * g.bot + bot * g.top, bot * g.bot); }

  fraction subtract(const fraction g)
  { return fraction(top * g.bot - bot * g.top, bot * g.bot); }

  bool lessthan(const fraction g)              // added after class
  { return top * g.bot < bot * g.top; }

  void print(ostream & out = cout)             // default parameter added after class
  { out << top << "/" << bot; } };

int main()
{ fraction half(1, 2);
  fraction quarter(1, 4);
  fraction seven_eighths(7, 8);

  fraction x = half.add(quarter);
  half.print();
  cout << " + ";
  quarter.print();
  cout << " = ";
  x.print();          // or I could have said   half.add(quarter).print();
  cout << "\n";

  ofstream fout("test.txt");                  // file part added after class
  if (fout.fail())
  { cerr << "failed to create test.txt\n";
    exit(1); }
  x.print(fout);
  fout << " < ";
  seven_eighths.print(fout);
  bool y = x.lessthan(seven_eighths);
  fout << " = " << (y ? "true" : "false") << "\n"; }