fraction2.cpp

#include <iostream>
#include <fstream>
using namespace std;

class Fraction
{
    private:
        double p, q;
    public:
        Fraction(double a = 0, double b = 1){p=a; q=b;};
        void print(){cout<<p<<"/"<<q;};
        Fraction sum(Fraction f){return Fraction(p*f.q+f.p*q, q*f.q);};
        Fraction sum(double d){return sum(Fraction(d, 1));};
        Fraction operator+(Fraction f){return sum(f);};
        Fraction operator+(double d){return sum(d);};
        Fraction operator=(const Fraction & f){p = f.p; q = f.q;};
        void setP(double value){p=value;};
        void setQ(double value){q=value;};
        double getP(){return p;};
        double getQ(){return q;};

        friend ostream & operator << (ostream & os, const Fraction & f);
        friend istream & operator >> (istream & is, Fraction & f);

        bool saveToFile(const string & filename)const;
        bool loadFromFile(const string & filename);
};

int main()
{
    Fraction temp1, temp2;
    cin >> temp1;
    cout << temp1 << endl;
    string filename = "temp.txt";
    cout << "Saving to file " << filename << endl;
    temp1.saveToFile(filename);

    cout << "Loading from file " << filename << endl;
    temp2.loadFromFile(filename);

    cout << temp2 << endl;
}

bool Fraction::saveToFile(const string & filename)const
{
    std::ofstream fout(filename);
    if (!fout)
        return false;

    fout<<*this;
    return true;
}

bool Fraction::loadFromFile(const string & filename)
{
    ifstream fin(filename);
    if (!fin)
        return false;

    fin>>*this;
    return true;
}

ostream & operator << (ostream & os, const Fraction & f)
{
    os << f.p;
    if (f.q != 1)
        os << "/" << f.q;
    return os;
}

istream & operator >> (istream & is, Fraction & f)
{
    string input;
    is >> input;
    int pos = input.find('/');
    string left, right;
    if (pos == -1)
    {
        left = input; right = "1";
    }
    else
    {
        left = input.substr(0, pos);
        right = input.substr(pos+1);
    }
    f.setP(stod(left)); f.setQ(stod(right));
    return is;
}