How to overload the ostream operator << to make it work with log4cxx in C++?

Question

Say I have a class A and an operator<< declared like so:

// A.h
class A
{
    // A stuff
};
std::ostream& operator<<(std::ostream& os, co         


        

Answer 1

Alan's suggestion of putting the user-defined operator in the std namespace works. But I prefer putting the user-defined operator in the log4cxx::helpers namespace, which also works. Specifically,

namespace log4cxx { namespace helpers {
    ostream& operator<<(ostream& os, const A& a);
} }

Answer 2

I don't have a compiler available right now but i think the problem is caused by trying to use insert operator on a constant string. "A: " << a

Answer 3

You could try declaring your operator << in namespace std (that's legal, since you're passing an instance of your user-defined type):

namespace std {
   ostream& operator<<(ostream& os, const A& a);
}