It is ok to like a guy after you know he likes you. That is perfectly normal and a part of life.
If he looks at you a lot, and smiles at you every time he sees you, he likes you. If compliments you, or talks to you often, he likes you. If he doesn't do that, he doesn't like you.
If a guy likes you but you don't know him he may look at you or walk by you whenever possible.
Not sure how you expect someone to magically know something.
If he says i like you
This is a tongue twister. And no.
If a guy likes you he will flirt with you but if he doesnt like you then he would act like he hates you.
If a guy likes you well I personally don't know but because I'm a girl I no what girls do when they like you they will constantly find a way to talk to you and will acked funny or not normal when there by you and will look at you all the time
if he acts like he doesn't
Ask him
You wait.
nothing! they maybe know that the guy you like likes you back!
kis and do it