removing last element of a list(scheme)

Question

So I have to remove the last element of a list in scheme.

For example, let\'s say I have a list (1 2 3 4). I need to return:

(1 2 3)
         


        

Answer 1

There is a reverse, but using it would not be very efficient. I suggest the following recursive function.

(define (remove-last lst)
    (if (null? (cdr lst))
        '()
        (cons (car lst) (remove-last (cdr lst)))))

(remove-last '(1 2 3 4)) ; returns '(1 2 3)

The if checks whether it is at the last element of the list.