If you write a tutorial or a book with code samples please take the time to ensure that (a) you cover everything that is needed to get your samples to work properly and (b) that your samples actually to work.

It is frustrating the bloody hell out of me typing your code character by character into my machine just to have my compiler screaming at me.

On that note: just wasted a week on rewriting a whole bloody library that was "broken" just to discover that the library works just fine but the freaking tutorial on the very page was faulty.