C++实现分数加法与乘法，输出结果只有一个

C++实现分数的加法与乘法

#include<iostream>
using namespace std;
class Fraction
{
public:
    Fraction()
    {
        top=1;
        base=1;
    }
    Fraction(int t,int b)
    {
        top=t;
        base=b;
    }

    void Format()
    {

        while(base!=0)
        {
            int n=MaxCo(top,base);


            if(top==0)
            {
                base=1;
            }
            else if(base<0)
            {
                top=-top;
                base=-base;
            }

            top=top/n;
            base=base/n;
            break;
        }

    }
    int MaxCo(int a,int b)
    {
        int temp;
        while(b!=0)
        {
            temp=a%b;
            a=b;
            b=temp;
        }
        return a>0?a:-a;
    }
    friend ostream&operator<<(ostream&o,Fraction&f)
    {
        while(f.base!=0)
        {
            f.Format();
            if(f.base==1)
                o<<f.top;
            else if(f.top<0)
                o<<f.top<<"/"<<f.base;

            return o;
        }
    }
    friend istream&operator>>(istream&i,Fraction&f)
    {
        i>>f.top>>f.base;
        return i;
    }
    friend Fraction operator+(Fraction&f1,Fraction &f2)
    {
        return Fraction(f1.top*f2.base+f1.base*f2.top,f1.base*f2.base);
    }
    friend Fraction operator*(Fraction&f1,Fraction &f2)
    {
        return Fraction(f1.top*f2.top,f1.base*f2.base);
    }

private:
    int top;
    int base;
};

int main()
{
    Fraction a;
    cin >> a;
    int f, m;
    cin >> f >> m;
    Fraction b(f, m);
    Fraction c, d;
    c = a + b;
    d = a * b;
    cout << c << endl;
    cout << d << endl;
    return 0;
}

输入1 -2
2 3
输出
[空格]
-1/3

我的解答思路和尝试过的方法

输出1/6 -1/3

friend ostream &operator<<(ostream &o,Fraction &f)
        {
            if(f.base!=0)//while(f.base!=0)
            {
                f.Format();

                if(f.base==1)
                    o<<f.top;
                else //if(f.top<0)
                    o<<f.top<<"/"<<f.base;
            }
            else
                o << "Error" << endl;
            return o;
        }