What's a good way to structure variable nested loops?

Question

Suppose you\'re working in a language with variable length arrays (e.g. with A[i] for all i in 1..A.length) and have to write a routin

Answer 1

Either the recursive algorithm

procedure register_combination( items )
        register_combination2( [], items [1:] )

procedure register_combination2( head, items)
    if items == []
        print head
    else
       for i in items[0]
           register_combination2( head ++ i, items [1:] )

or the same with tail calls optimised out, using an array for the indices, and incrementing the last index until it reaches the length of the corresponding array, then carrying the increment up.