Trouble with istream overload in descendant class c++

Question

I am having trouble with what I believe to be the insertion operator overload of my program. It is an assignment for a beginners c++ class in which I am supposed to use descendant functions to perform tasks with complex numbers and vectors. When I input a number for either class it is either not being read in correctly or assigned to the array correctly. I have been trying to sort this out for over an hour now and nothing I try seems to work.

The classes:

class pairs
{
protected:
    double a;
    double b;
public: 
    pairs(): a(0), b(0){}
    pairs(const pairs&p): a(p.a), b(p.b){}
    pairs(double x, double y): a(x), b(y){}
    pairs operator +(pairs& second){
        return pairs(a+second.a, b+second.b);
    }
    pairs operator -(pairs& second){
        return pairs(a-second.a, b-second.b);
    }
    bool operator ==(pairs& second){
        bool tf=false;
        if (a==second.a && b==second.b)
            tf=true;
        return tf;
    }
};
class comp:public pairs
{
public:
    comp():pairs(){}
    comp(const pairs&p):pairs(p){}
    comp(double x, double y):pairs(x, y){}
    comp operator *(comp& second){
        comp mew;
        mew.a=(a*second.a)-(b*second.b);
        mew.b=(a*second.b)+(b*second.a);
        return mew;
    }
    comp operator /(comp& second);
    friend ostream& operator << (ostream& fout, comp& num){
        if(num.b<0)
            cout<<num.a<<num.b<<"i";
        else
            cout<<num.a<<"+"<<num.b<<"i";
        return fout;
    }
    friend istream& operator >> (istream& fin, comp num){
        char sym, i;
        cout<<"Enter a complex number in a+bi or a-bi form: ";
        cin>>num.a>>sym>>num.b>>i;
        if(sym=='-')
            num.b*=-1;
        return fin;
    }
};
class vect:public pairs
{
public:
    vect():pairs(){}
    vect(const pairs&p):pairs(p){}
    vect(double x, double y):pairs(x, y){}
    vect operator*(double num){
        return vect(a*num, b*num);
    }
    int operator*(vect num){
        int j;
        j=(a*num.a)+(b*num.b);
        return j;
    }
    friend ostream& operator << (ostream& fout, vect& num){
        cout<<"<"<<num.a<<","<<num.b<<">";
        return fout;
    }
    friend istream& operator >> (istream& fin, vect num){
        char beak, com;
        cout<<"Enter vector in <a,b> form: ";
        cin>>beak>>num.a>>com>>num.b>>beak;
        return fin;
    }
};

The call to the insertion operators looks like:

        comp temp;
        int store;
        cin>>temp;
        cout<<"Where do you want to store this (enter 1-6): ";
        cin>>store;
        while(store<1 || store>6)
        {
            cout<<"Invalid location. re-enter: ";
            cin>>store;
        }
        six[store-1]=temp;
        break;

It's the same for vect if you change 'comp temp' to 'vect temp' An array of comp or vect size 6 is passed into the function, which is why six[] is not shown as being declared.

I tried running the program and printing temp before it was assigned to the array and both values where still at zero and I am at a loss for why that may be.

Any advice is greatly appreciated. :]

The best advice I can give is: Run that code in a debugger and step through line by line, to narrow what's the cause of your troubles. — πάντα ῥεῖ, Apr 27 '15 at 16:08
The parameter should be `comp& num`, and `>>` is not expected to perform any user interaction — only read from the given stream. — molbdnilo, Apr 27 '15 at 16:17
Thanks @molbdnilo the problem was in the parameter! Works perfectly now. :] — abstractbryan, Apr 27 '15 at 20:23

score 0 · Answer 1 · answered Apr 27 '15 at 17:31

You should use the std::istream& in the operator>>() implementation to read from:

friend istream& operator >> (istream& fin, vect num){
    char beak, com;
    // cout<<"Enter vector in <a,b> form: ";
    fin >> beak >> num.a >> com >>num.b >> beak;
 // ^^^
    return fin;
}

Same for the other operator>>() overloads.

Also you want to output the prompt outside of using the overloaded input function (that's why I commented it above).

Trouble with istream overload in descendant class c++

1 Answers1