> you would never use U"hello!" in pre C11/C++11. I have seen real world code which does almost exactly that and which broke (fortunately with a compiler error

> you would never use U"hello!" in pre C11/C++11. I have seen real world code which does almost exactly that and which broke (fortunately with a compiler error rather than silently changed code) when compiled with a C++11 compiler due to the new user-defined literal syntax. I agree that it's rare, but it can happen.