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caar, cadr

Type: - function (subr)

Source: - xllist.c

Syntax

(caar expr)
(cadr expr): expr - a list expression
returns - the result of the last car function

Description

The 'caar' and 'cadr' functions go through the list expression and perform a sequence of car or cdr operations. The sequence of operations is performed from right to left. So 'cadr' does a cdr on the expression, followed by a car. If at any point the list is NIL, then NIL is returned. If at any point a car operation is performed on an atom [as opposed to a list] an error is signalled:

error: bad argument

The 'cadr' function returns the same result as the second function.

Examples

(setq mylist '((1A 1B) (2A 2B) (3A 3B)))

(caar mylist)  => 1A
(cadr mylist)  => (2A 2B)

(caar 'a)      => error: bad argument
(caar nil)     => NIL

Note: The 'c...r' functions are part of the historical Lisp functions. You may find it easier to work with the modern lisp functions like nth and nthcdr.