How to overload << operator for a class?

Hi,

How do we overload the stream operator for a class again? I want to do this:

class Something {
    int a;
    double d;
    void OverloadedStreamOperator <<()
    {
        ????
    }
};

int main()
{
    Something s;
    s.a = 44;
    s.d = 34.34;
    cout << s << endl;
}

Thanks
DJ_AM_JuiceboxAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Infinity08Commented:
 ostream& operator<< (ostream& os, const Something& s)
  {
    return os << s.a << " " << s.d << endl;
  }
0
DJ_AM_JuiceboxAuthor Commented:
I tried adding that as a member of my class but get this compiler error:

     binary 'operator <<' has too many parameters
0
jkrCommented:
Note that this is not a member operator, but an operator at global scope, so to make that work you'll usually have to make it a 'friend' of your class to use for non-public members also, i.e.

 ostream& operator<< (ostream& os, const Something& s)
  {
    return os << s.a << " " << s.d << endl;
  }
class Something {

friend ostream& operator<< (ostream&, const Something&);

    int a;
    double d;

};
0
Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

DJ_AM_JuiceboxAuthor Commented:
is there any way to make it a member of the class? Otherwise I'll have all these friends for all my classes at global scope?
0
Infinity08Commented:
Or completely with your class :

class Something {
    int a;
    double d;
  public :
    friend istream& operator>>(istream& is, Something& s);
    friend ostream& operator<<(ostream& os, const Something& s);
};

istream& operator>>(istream& is, Something& s) {
  is >> s.a;
  is >> s.d;
  return is;
}
ostream& operator<<(ostream& os, const Something& s) {
  os << "a = " << s.a << endl;
  os << "d = " << s.d << endl;
  return os;
}
0
jkrCommented:
>>is there any way to make it a member of the class?

No, the '<<' operator has a 'left to right' association. You can make a

Something s;

s << "whatever";

a member, but not a

ostream os;

os << s;
0
jkrCommented:
BTW, you could also add a 'write()' method like

class Something {
    int a;
    double d;
    ostream& write(ostream& os) const
    {
        os << a;
        os << d;

        return os;
    }
};

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
DJ_AM_JuiceboxAuthor Commented:
yeah i ended up just doing a write() function. How sad!

Thanks
0
jkrCommented:
I'd actually have chosen the 'friend' approach. It is just a C++ concept that your friends have access to your privates (pardon the pun ;o)
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
C++

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.