nth [Accessor]

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::

section elt [Accessor] , @xref{first; second; third; fourth; fifth; sixth; seventh; eighth; ninth; tenth} , section nthcdr [Function]

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