Дроби для Насти

//Написано жесть, почти в каждой строчке ошибка.
//Поправил drobi - теперь работает, вроде. Fraction не работает, лучше замени его тем, с предыдущей задачи.
//ПРотестируй обязательно.

#include <iostream>
#include <cstdlib>
using namespace std;
const int mod=1000*1000*1000;

class fraction
{
protected:
        int fir, sec;
public:
        void init (int a=0, int b=0)
        {
                fir=a; sec=b;
        }

  friend istream& operator>> (istream& stream, fraction& d){
                char str[50]; int a=0, b=0, znak=1;
                stream >> str; int i=0;
                if (str[0]=='-') {znak*=(-1); i++;}
                while (str[i]!='.') {
                        a=a*10+(int)str[i]-'0';
                        i++;
                }
                a*=znak;
                i++;
                while (str[i]) {
                        b=b*10+(int)str[i]-'0'; i++;
                }
                while (b<mod/10) {
                        b*=10;
                }
                if (a<0) {a--; b=mod-b;}
                d.init (a, b);
    return stream;
  }

  friend ostream& operator<< (ostream& stream, const fraction& d) {
    int sec = d.sec;
    int fir = d.fir;
    if (fir<0 && sec!=0) {
      fir++;
      sec = mod-sec;
    }
    while (sec%10==0) sec/=10;
    stream << fir << "." << sec;
    return stream;
  }

        fraction (int a, int b){init (a,b);}
        fraction () {}
        fraction (const fraction & obj):fir(obj.fir), sec(obj.sec){}

        fraction & operator = (const fraction & q)
        {
                fir=q.fir; sec=q.sec; return *this;
        }
        virtual fraction operator+ (const fraction & oth)
        {
                int a, b;

                b=(sec+oth.sec)%mod;
                while (b<mod/10) {
                        b*=10;
                }
                a=fir+oth.fir+(sec+oth.sec)/mod;
                fraction z(a, b);
                return z;
        }
        friend int red (int num, int den);
};

int red (int a, int b) //reduction
{
  while (a!=0 && b!=0) {
    if (a>b) a = a%b;
    else b = b%a;
  }
  return a+b;
}





class drobi: public fraction
{
    int thir;
public:
    drobi (): fraction() { thir = 1;}
    drobi(int x, int y, int z): fraction(x, y), thir(z) {};
    drobi(const drobi& obj) {*this = *&obj;}
    drobi operator+ (const drobi& obj) const
{
    drobi temp;
    temp.fir = fir+obj.fir;
    temp.sec = sec*obj.thir+thir*obj.sec;
    temp.thir = thir*obj.thir;
    while (temp.sec >= temp.thir) {
        temp.fir++;
        temp.sec -= temp.thir;
    }
    int reduct = red(temp.sec, temp.thir);
    temp.sec /= reduct; temp.thir /= reduct;
    return temp;
}

    friend istream& operator>> (istream& in , drobi& obj)
    {
        in >> obj.fir >> obj.sec >> obj.thir;
    return in;
    }
    friend ostream& operator<< (ostream& out, const drobi& obj)
    {
        out << obj.fir << " " << obj.sec << " " << obj.thir << endl;
    return out;
    }

};



int main ()
{
    fraction ab(1,006), bb(2,936);
    cout << "sum_fr " << ab + bb << endl;

    drobi ad(-1, 1, 2), bd(5,0,7);
    cout << "sum_dr " << ad + bd << endl;

    fraction *arr[4];
    fraction sum_fr(0, 0); drobi sum_dr(0, 0, 1); int fr_num = 0, dr_num = 0;
    arr[0] = new fraction(2,5);
    arr[1] = new drobi(1,9,10);
    arr[2] = new drobi(2,1,4);
    arr[3] = new fraction(-9,1);
    drobi *cur;

    for (int i = 0; i < 4; ++i) {
        cur = dynamic_cast<drobi*>(arr[i]);
        if (!cur) {
            sum_fr = sum_fr + *arr[i];
            ++fr_num;
        }
        else {
            sum_dr = sum_dr + *cur;
            ++dr_num;
        }
    }
    cout << sum_fr << " " << sum_dr;
    cout << fr_num << " " << dr_num;
return 0;
}