LISP Length function

USING COND

(defun my-length (list1)
         (cond ( (null list1) 0 )
                    (t (+ 1 (my-length (cdr list1)) ))
         )
)

USING IF

(defun my-length (list1)
         ( if (null list1) 0 (+ 1 (my-length (cdr list1))) )
)