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<html><head><title>XLISP caar, cadr</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>caar, cadr</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>caar</b> <i>expr</i>)<br>
(<b>cadr</b> <i>expr</i>)</dt>
<dd><i>expr</i> - a list expression<br>
returns - the result of the last <a href="car.htm">car</a> function</dd>
</dl>
</div></p>
<h2>Description</h2>
<p>The 'caar' and 'cadr' 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. The sequence of operations is
performed from right to left. <nobr>So 'cadr'</nobr> does a
<a href="cdr.htm">cdr</a> on the expression, followed by a
<a href="car.htm">car</a>. <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
<nobr>[as opposed</nobr> to <nobr>a list]</nobr> an error is signalled:</p>
<pre class="example">
<font color="#AA0000">error: bad argument</font>
</pre>
<p>The 'cadr' function returns the same result as the
<a href="second.htm">second</a> function.</p>
<h2>Examples</h2>
<pre class="example">
(setq mylist '((1A 1B) (2A 2B) (3A 3B)))
(caar mylist) => 1A
(cadr mylist) => (2A 2B)
(caar 'a) => <font color="#AA0000">error: bad argument</font>
(caar 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>
<hr>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
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<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
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