This function has two forms. The first returns the object on the floor in the given character's room that matches the given string. If there is no match, it returns null. The parsing includes checking for things like 'corpse' vs '2.corpse'. This will only match an object that the given character is actually aware of: if the object is invisible and he can't see invisible things, for instance, then that won't be matched.
The second form returns a complete list of all objects on the floor of the specified room.