Notepad++ doesn't tell you jack squat. The most it'll tell you is if it thinks you spelled a word wrong, or if you're coding in HTML, it'll color code whatever it thinks are supposed to be inside quotation marks.
@OP, what IDE are you using? Notepad++ is just Notepad's hotter, slightly smarter friend.
Yes. I said "no other IDE" because I wasn't sure if Notepad++ qualified as an IDE. Having a closer look it seems like it's just a code editor. My point is that if he uses Notepad++ he is probably not using an IDE at the same time, but of course he could be. In either case he's probably using a compiler (integrated in an IDE or standalone).
Frummel, if you are not using a compiler I suggest you start using one because writing C++ code without a compiler is hard to do. The compiler can give you descriptive error messages that helps you correct your code, and it also allow you to run your program so that you can test it.