Does a guy like you if he came up out of nowhere and started talking to me?

It doesn't necessarily mean that he's in love with you.

Maybe he was surprised to see you after a long time or maybe he had something important to ask/tell you.

I know that if I liked some girl I wouldn't behave like that.

I would probably ignore her and make her like me.

Well, not ignore, but act cool and I wouldn't show her that I like her.

But, that's just me...

So, the answer to your question is, probably not.