functions or types

Arrays are fine for things which are static, but dynamic entities like doors are perfect for Types. It gives you the ability to have a field for the door's status ( open/closed ) and it allows you to easily create and destroy doors ( that might or might not be useful, depending on the game. )

If you're looking for a little reading material to get you more comfortable with types, you could try these articles on the subject :

Arrays and Types - Krylar

http://www.blitzcoder.com/cgi-bin/articles/show_article.pl?f=gamekrylar10192000.html

The Definitive Guide to Types - Muttering Goblin

http://www.blitzcoder.com/cgi-bin/articles/show_article.pl?f=mutteringgoblin09232002232208.html