memq

OBJECT LIST -> LIST

メンバーかどうか確認する

code: fns.c

DEFUN ("memq", Fmemq, Smemq, 2, 2, 0,

doc: /* Return non-nil if ELT is an element of LIST. Comparison done with `eq'.

The value is actually the tail of LIST whose car is ELT. */)

(Lisp_Object elt, Lisp_Object list)

{

Lisp_Object tail = list;

FOR_EACH_TAIL (tail)≤

if (EQ (XCAR (tail), elt))

return tail;

CHECK_LIST_END (tail, list);

return Qnil;

}

code: example.el

(memq 1 '(1 2 3))

;; => (1 2 3)

(memq 2 '(1 2 3))

;; => (2 3)

(memq 3 '(1 2 3))

;; => (3)

(memq 4 '(1 2 3))

;; => nil