如何调整表内元素？

高级用户

if应该是这样吧 :)

(if  (and (>= i 0) (< i (length li)) (/= i k) (>= k 0) (< k (length li)) )

)

照瓢画葫芦，看看我的有问题不

;;将表内第4个和第5个元素交换

(defun c:test2()
  (setq L '("a" "b" "1" "2" "3" "c"))
  (setq i 3)
  (setq ii 4)
  (setq new (jh L  i ii))
)

(defun jh(li a b / aa bb )
  (if (and (>= a 0) (>= b 0) (< a (length li)) (< b (length li)) )
   (progn
    (setq aa (nth a  li))
    (setq bb (nth b  li))
    (setq li (subst "x" bb li)
          li (subst bb aa li)
          li (subst aa "x" li)
    )
   )
  )
)