Where should non-member operator overloads be placed?

Question

I want to overload operator<< for my class. Should I add this overloaded definition to the std namespace? (since the ostream operator&l

Answer 1

Don't add it to the std namespace, place it in the same namespace as your class. The purpose of a namespace is to prevent collisions. The standard says

17.4.3.1 Reserved names

It is undefined for a C++ program to add declarations or definitions to namespace std or namespaces within namespace std unless otherwise specified. A program may add template specializations for any standard library template to namespace std. Such a specialization (complete or partial) of a standard library template results in undefined behavior unless the declaration depends on a user-defined name of external linkage and unless the specialization meets the standard library requirements for the original template.