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<html><head><title>XLISP rplacd</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
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<hr>
<h1>rplacd</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>
<dl>
<dt>(rplacd list expr)</dt>
<dd><i>list</i> - the list to destructively modify<br>
<i>expr</i> - the expression to replace the
<a href="cdr.htm">cdr</a> of <i>list</i><br>
returns - the list node after updating the
<a href="cdr.htm">cdr</a></dd>
</dl>
<h2>Description</h2>
<p>The 'rplacd' function destructively modifies the
<a href="cdr.htm">cdr</a> of 'list' and replaces it with the
'expr'. The destructive aspect of this operation means that the actual
symbol value is used in the list-modifying operations, not a copy. 'list'
must evaluate to a valid list.</p>
<p>An atom or <a href="nil.htm">NIL</a> for 'list' will result in
an error:</p>
<pre class="example">
<font color="#AA0000">error: bad argument type</font>
</pre>
<h2>Examples</h2>
<pre class="example">
(setq a '(1 2 3)) <font color="#008844">; set up A with (1 2 3)</font>
(rplacd a 'new) <font color="#008844">; returns (1 . NEW)</font>
(print a) <font color="#008844">; prints (1 . NEW)</font>
<font color="#008844">; note that A is modified</font>
(rplacd a '(a new list)) <font color="#008844">; returns (1 A NEW LIST)</font>
(rplacd '(1 2 3) '(more)) <font color="#008844">; returns (1 MORE)</font>
(rplacd 'a 'b) <font color="#008844">; error: bad argument type</font>
(rplacd NIL 'b) <font color="#008844">; error: bad argument type</font>
</pre>
<p>See the
<a href="../manual/xlisp-man-017.htm#rplacd">rplacd</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
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