Painting - painting concrete floor

I live in a rented apartment with two dogs who are destroying the carpet. I'd like to remove it but I don't want to spend a lot of money for tile or new carpet because I'm renting. I was thinking of taking it up and painting the concrete underneath. The concrete isn't smooth but it isn't so rough that it hurts my feet to walk on it. My question is, does concrete need to be smooth to paint it?

Painting concrete is very easy. It takes paint well, and provided you use the correct paint it will last. Concerning your question of painting rough concrete, you might want to use some floor leveling compound to smooth up the rough areas. Remember paint is a thin layer, what you see when you start is what you are going to end up with.
You might be sorry that you pulled up the carpet and went with bare concrete. I walk on it all day long, and it will make your feet and back hurt. You might want to think about something like cheap indoor/outdoor carpet.
Good luck,