[c++] What's this error?
 

What does this error mean?

Undefined first referenced
symbol in file
operator<<(std::basic_ostream<char, std::char_traits<char> >&, Diamond&)/var/tmp//ccR39vYu.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status


I'm trying to overload the << operator within a class, and this is the only part that I can't seem to get working. Let me know if you need more code or if you know what I should check out to fix it. Thanks

Show the the code in question.

It's a linker error meaning operator<< with those parameters is not defined. Remember that if you're trying to do something like
Class c;
cout << c;
the operator<< function must either be a member of ostream or a global function. If you make it a member of Class it's not going to work the way you expect.

What nonsensical is basically saying is put it as a global function in your header file (not part of the class) and then make that function a friend of your class to get private access.