/* rational numbers in C++ */
using namespace std;
#include<iostream>

// interface:
class rational
{
 private:
  int num;
  int dem;
  int gcd(int a, int b) {if (a==0) return b; else return gcd(b%a,a);}
 public:
  rational(int n, int d);  // constructor
  ~rational();             // destructor
  void invert();
  int equals(rational* other);  // rational equality
  void multx(rational* b);      // destructive multiplication
  rational* mult(rational* b);  // constructive multiplication
  void print();
};

// implementation:

rational::rational(int n, int d)  // constructor
    {  int g;
       num = n;  if (d!=0) dem = d; else dem = 1;
       g = gcd(num,dem);
       num = num/g;   dem = dem/g;      
    }  
rational::~rational() {} // destructor
  
void rational::invert() 
    { if (num==0) return;
      int temp;
      temp = num;  num = dem; dem = temp;
    }

int rational::equals(rational* other)
    { return num*other->dem == dem*other->num; }

void rational::multx(rational* b)
    {
      num = num*b->num;  dem = dem*b->dem;
    }

rational* rational::mult(rational* b)
    { return new rational(num*b->num, dem*b->dem); }
 
void rational::print() { cout << num << "/" << dem; }


int main()
{
  rational *a, *b;
  a = new rational(1,2);  b = new rational(2,4);
  cout << a->equals(b) << endl;
  a->multx(b);
  b = a->mult(b);
  a->print();  cout << endl;
  b->print();  cout << endl;
}