Having seen a thousand plus one versions of this thread, tried my own back in the day, and seeing the same answers trotted out which are invariably *meant* to be helpful, but aren't... I thought I'd answer it.
First thing to remember. Boys do not spend five hours thinking about the way you said, 'hi', and what that means. (Most boys) A lot of the guys on internet forums are unlike boys 'out there'. That is, they've read stuff on boards like this, and so on. Girls can analyse behaviour and words intensely. Boys are less likely to. So.
Rule 1: If the 'signs' are really, really subtle, to the point that only you notice them.... No. None of us can tell you if he likes you.
Flirting. It might not be easy to tell, but there are give aways. When a guy flirts, he will smile more, angle in so his body is aligned with yours, make a lot more eye-contact, and most of the time, becomes tactile - he touches you more often.
Rule 2: If he keeps his distance, but makes suggestive remarks, he's kidding around. Some guys flirt just because it's an easy way of interacting with a girl.
This whole body language thing. Boys aren't particularly subtle, as we've covered. If he's thinking about you *that* way, it's possible he'll 'accidentally' touch areas of your anatomy; his hand might touch the small of your back, your waist, your bum. It's more of an indication than just hugging and cuddling
Rule 3: If he's touching you a lot, in places that are generally 'attractive', then yeah, he probably does like you.
Smiling. Yes, it's nice, and guys look fairly cute when they smile. It's a mark of confidence, of happiness, of.... flirting? Sorry to say this, girls, but a guy *smiling* at you is not necessarily an indication that he wants to fling you on a bed and have his way with you. He could just be, you know, friendly.
Rule 4: One indication of body-language flirting is not an 'all systems go' signal.
And finally... You can describe his behaviour as often as you like, to a sympathetic audience, but what it always comes down to is... YOU are the one who can see what he's like. You're the one who interacts with him. You're the one who can steer the conversations. None of us can tell you 'for sure' if he does or does not like you. And it's not going to change whether he does or doesn't, if we say one way or the other.
Rule 5: Only you, really, know.