From: richardeng <richardeng@foxmail.com>
To: Alan Mackenzie <acm@muc.de>
Cc: help-gnu-emacs@gnu.org
Subject: Re: How could I modify list element?
Date: Wed, 10 Dec 2008 01:43:23 +0800 [thread overview]
Message-ID: <493EAE3B.8020707@foxmail.com> (raw)
In-Reply-To: <20081209163258.B7055@colin2.muc.de>
Alan Mackenzie wrote:
>
>
> On Tue, 9 Dec 2008, richardeng wrote:
>
>> Hi all,
>> setcar/setcdr is not convenient.
>> In a long list, ex.
>> (setq a '(a b c d e f g))
>> I want to change 'e to 'E.
>> I need a function: (set-list-elt list old-elt new-elt)
>>
>> How? translate list to vector, modify, then turn it back???
>
> Try this (not tested):
>
> (defun change-nth (liszt, n, nieuw)
> (while (> n 0)
> (setq liszt (cdr liszt)
> n (1- n)))
> (if liszt
> (setcar liszt nieuw)))
>
(setq aaa '(1 2 3 4 5 b a "ccc"))
(change-nth aaa 3 'BB)
aaa --> (1 2 3 BB 5 b a "ccc") , it works, thank you!
next prev parent reply other threads:[~2008-12-09 17:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-09 14:15 How could I modify list element? richardeng
2008-12-09 15:37 ` Alan Mackenzie
2008-12-09 17:43 ` richardeng [this message]
[not found] ` <mailman.2345.1228845668.26697.help-gnu-emacs@gnu.org>
2008-12-09 20:30 ` Andreas Politz
2008-12-09 17:21 ` Thierry Volpiatto
2008-12-09 17:26 ` Thierry Volpiatto
[not found] <mailman.2319.1228836378.26697.help-gnu-emacs@gnu.org>
2008-12-09 16:36 ` Andreas Politz
2008-12-09 20:46 ` Niels Giesen
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