Question

Write a Scheme function that takes a list of integers and returns all odd integers on the list in the original order:

(odd-numbers `(2 4 9 16 25 7)) (9 25 7)

Hint: 2 (remainder 13 5) 3

Please explain every step

Answer 1

(define (odd-numbers l)
   ; check if list is empty
   (cond ((null? l) '())
       ; check if 1st number of list is even
       ; and if its even then skip that number
       ; and find odd in remaining
       ((even? (car l)) (odd-numbers (cdr l)))
       ; if 1st number of list is not even ie odd
       ; then add that to "new list" with remaining odd of "original list"
       (else (cons (car l) (odd-numbers (cdr l))))
   )
)

; Note: "even?" is in-build function

; (odd-numbers '(2 4 9 16 25 7))