mykphyre
http://www.cplusplus.com/reference/
It has great reference for the C++ and C standard libraries. The best thing is that there are simple but _very_ good code examples accompanying each function description showing how to use it in context. Can't recommend this reference highly enough.
Coincidentally, my girlfriend is just graduating college from learning to a be a grade school teacher. She's taught me something very important over the last year or so: that school is not really about learning the subjects your teachers are trying to teach you, it's about you developing as a person. Maybe it would help if you thought of high school as a social learning environment rather than an academic one. Let me also say that in no way do I mean that just because you're in 10th grade does that mean that you're not mature or intelligent. Everyone can improve themselves in many ways, not just academically, and that's what I suggest you focus on in school.
You're going to have boring tasks to do when you have a job, or when you live on your own, so it's best to learn how to get through them now and appreciate the genuinely interesting subjects while you can. I have had about a 50/50 split with good/bad professors in college and I'm assuming that this carries over into the professional world. You'll probably have some co-workers who are like you, and care about doing well, and some that just do it for the money.
You're way ahead of me as far as figuring these things out; I didn't start programming until the middle of my 3rd year in college. I also didn't read PG's high school essay until very recently, and I wish I had read it when I was your age. At the last career fair I went to, all three of the recuiters I talked to told me they wanted candidates with programming experience outside of class. You're well ahead of the curve and it sounds like you've got a good head on your shoulders. Try not to get discouraged and remember there are lots of people out there that feel the same way you do.
I hope this gives you some perspective and encouragement. I wish you the best of luck in your endeavors.