Thread: Bitshift operator overloading help (weird)

Hey,

I'm working on a Solaris box and trying to overload the left bitshift operator as a "print" function in an object I have, so I can do:

Code:

std::cout << obj_name << std::endl;

Every possible example I can find has 2 arguments, LHS, RHS. The prototype for this system appears to only have one, the RHS.

If I add a second argument to the overloaded definition, I get:

Code:

file_name.h:53: error: `std::ostream& class_name::operator<<(std::ostream&, const class_name&)' must take exactly one argument

I put a printf inside the overloaded operator and put:

Code:

obj << std::cout;

And it prints the hardcoded string literal in the operator overloading..

Does this mean I can only overload the RHS, or am I doing it wrong..

I mean I think I could do it like:

Code:

std::cout << obj << std::cout

Because it returns an ostream reference..


Additional Notes:
I didn't friend the overload, it's in the header in the class declaration.

Originally Posted by NeonBlack

I would keep it. While your Display() function serves the single purpose of printing to std::cout, you can also use operator<< with other types of streams, such as file streams and stringstreams.

If it was my own project, I'd say sure, but it's for a school project. It wasn't required to overload the operator, they didn't get even get to it yet - just figured it'd be convenient to just cout the puzzle, like how everything in java has a toString(), you can just cout the object...then I implemented it, and it didn't look as nice as just ptr->Display();. You know?

Originally Posted by laserlight

Declare the function to be inline, e.g.,

Code:

inline std::ostream& operator<<(std::ostream& out, const X& x)
{
    return x.Display(out);
}

Ah, yeah, thanks. Not sure why I didn't think of that, it was inline when it was a member function...start to not think right after coding too long...lol.

Originally Posted by NeonBlack

I would keep it. While your Display() function serves the single purpose of printing to std::cout, you can also use operator<< with other types of streams, such as file streams and stringstreams.

Well if you weren't going to use operator overloading, I think a Display function could be modified to work with an ostream argument, which gives you all the polymorphism you need to work with other types of streams.

operator>> and operator<< are only a convention -- a very widely appreciated convention, but you could easily implement both to please everyone.