This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
That works if you don't count toCharArray as a "standard library function". Which is fine with me, it's up to the question-setter to define what a "library function" is and how you tell whether it's "standard" or not.