If you do freelance work for a company and don't explicitly sign a contract in relation to Intellectual property. Then, who owns the code? Can I, as a programmer re-use this code? Can they as the customer re-sell the code? or develop it further and re-sell.

Code re-use is one of the best things about object orientated programming - so, I'd of course like to be able to reuse code i write. Usually, not lots of it but just bits and pieces.