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Index
first Conses Dictionary endp
Accessor

nth

nth n list ⇒ object

(setf ( nth n list) new-object)

Arguments and Values

na non-negative integer.
lista list,

which might be a dotted list or a circular list.

objectan object.
new-objectan 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; second; third; fourth; fifth; sixth; seventh; eighth; ninth; tenth, nthcdr

Backlinks

Conses as Lists, Conses Dictionary, elt, first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, Function Call Forms as Places, last, nth-value, nthcdr, Symbols in the COMMON-LISP Package