empty array

Hi the list

Is it possible to create an empty matrix ? I do not mean an matrix with 
a single value that is NA (which is not empty) but a real empty one, 
with length=0.

I do not understand why we have length(numeric()), length(factor()) and 
length(character()) to zero, and length(array()) to one... Any rason for 
that ?

Thanks

Christophe