What are ways to know when a guy likes you at school when you never talk and always look at each other in the halls but are friends?

Well if you are really friends and only friends, then you are definitely friends.

but if you hint that he likes you, and he looks at you all the time, then its time he realised how good lookin you are and he likes you. If you dont know, then go up and ask. If you are friends already then that means he should be able to tell you if he likes you or not.