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<html><head><title>XLISP cdar, cddr</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
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<hr>
<h1>cdar, cddr</h1>
<hr>
<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
<td><nobr>Type:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>function (subr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xllist.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<p><div class="box">
<dl>
<dt>(<b>cdar</b> <i>expr</i>)<br>
(<b>cddr</b> <i>expr</i>)</dt>
<dd><i>expr</i> - a list or list expression<br>
returns - the result of the last <a href="cdr.htm">cdr</a>
function</dd>
</dl>
</div></p>
<h2>Description</h2>
<p>The 'cdar' and 'cddr' functions go through the list expression and perform a
sequence of <a href="car.htm">car</a> or
<a href="cdr.htm">cdr</a> operations. <nobr>The sequence</nobr> of
operations is performed from right to left. So 'cdar' does a
<a href="car.htm">car</a> on the expression, followed by <nobr>a
<a href="cdr.htm">cdr</a></nobr>. <nobr>If at</nobr> any point the list is
<a href="nil.htm">NIL</a>, then <a href="nil.htm">NIL</a> is returned.
<nobr>If at</nobr> any point a <a href="car.htm">car</a> operation is
performed on an atom [as opposed to a list] an error is signalled:</p>
<pre class="example">
<font color="#AA0000">error: bad argument</font>
</pre>
<h2>Examples</h2>
<pre class="example">
(setq mylist '((1A 1B) (2A 2B) (3A 3B)))
(caar mylist) => 1A
(cadr mylist) => (2A 2B)
(cdar mylist) => (1B)
(cddr mylist) => ((3A 3B))
(cdar 'a) => <font color="#AA0000">error: bad argument</font>
(cdar nil) => NIL
</pre>
<p><b>Note:</b> The '<nobr>c...r</nobr>' functions are part of the
historical Lisp functions. You may find it easier to work with the modern
lisp functions like <a href="nth.htm">nth</a> and
<a href="nthcdr.htm">nthcdr</a>.</p>
<p>See also:</p>
<ul>
<li><nobr>Contents → <a href="../manual/contents.htm#list-functions">List Functions</a></nobr></li>
<li><nobr>Tutorials → Lisp Hints → <a href="../tutorials/lisp-hints.htm#list-accessors">List Accessors</a></nobr></li>
</ul>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
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