nth

nth Accessor

Syntax:

nth n list → object

(setf (nth n list**)** new-object**)**

Arguments and Values:

n—a non-negative integer .

list—a list, which might be a dotted list or a circular list.

object—an object.

new-object—an object.

Description:

nth locates the nth element of list, where the car of the list is the “zeroth” element. Specifically, (nth n list) ≡ (car (nthcdr n list))

nth may be used to specify a place to setf. Specifically,

(setf (nth n list) new-object) ≡ (setf (car (nthcdr n list)) new-object)

Examples:

(nth 0 ’(foo bar baz)) → FOO 
(nth 1 ’(foo bar baz)) → BAR 
(nth 3 ’(foo bar baz)) → NIL 
(setq 0-to-3 (list 0 1 2 3)) → (0 1 2 3) 
(setf (nth 2 0-to-3) "two") → "two" 
0-to-3 → (0 1 "two" 3) 

See Also:

elt, first, nthcdr

Expanded Reference: nth

tip

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(nth )