<human>: Can you provide a brief overview of the text?

I just finished school and i'm about to go to college. In school i knew more than a handful of 'friends' who would act really friendly and chat until they asked for help I dunedin and when i did help them, they would thank me and then 'disappear' if you know what i mean. The problem was they really knew how to seem friendly and overstated in me until im done helping them and then we're back to "face i see in class mode, even if i try to talk to them they would reply politely  until im done then forget my existence once more. And now we graduated and it's summer and as expected,i haven't heard from any of them. So i ask you all, since college will probably be filled with this type of people and not to sound selfish, i dont want to waste my time and life on these 'friends' (especially as an engineering major), so how do you.figure out who's a real friend  and who's just using you, and has this ever happened to any of you? Also, what's the best way to deal with them?
<bot>: was used in school by 'friends' , want to avoid this type of people in college. How do i filter them out from real friends and how do i deal with them?