c++ multiple definitions of operator<<

Question

I am attempting to override the << operator for a class. The purpose is basically to implement a toString() like behavior for my class, so t

Answer 1

You are putting the definition of a function in a .h file, which means that it will appear in every translation unit, violating the One Definition Rule (=> you defined operator<< in every object module, so the linker doesn't know which is "the right one").

You can either:

• write just the declaration of your operator (i.e. its prototype) in the .h file and move its definition to rectangle.cpp
• make operator<< inline - inline functions are allowed to be defined more than once, as long as all the definitions are identical.

(Also, you should use header guards in your includes.)