LISP: Omit first value in list by reference

Question

I just want to omit first value of list using a function but below code is returning same list
I dont want to return from a fucntion Code:

 #! /usr/bin/clisp    

(defun omit(lstold)
    (setf lstold (cdr lstold))
)
(setq x (list 3 1 2))
(omit x)
(write x)  --> gives output 3 1 2 ... why?

Answer 1

That's because you didn't modify your x, but you just modified your local lstold, and you returned it to nowhere (i.e. didn't capture returned value).