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<html><head><title>XLISP equal</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>equal</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>predicate function (subr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xllist.c, xlsubr.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<p><div class="box">
<dl>
<dt>(<b>equal</b> <i>expr1 expr2</i>)</dt>
<dd><i>exprN</i> - arbitrary Lisp expressions<br>
returns - <a href="t.htm"> T </a> if the expressions
are structurally equivalent, <a href="nil.htm">NIL</a> otherwise</dd>
</dl>
</div></p>
<h2>Description</h2>
<p>Two expressions <nobr>are 'equal'</nobr>:</p>
<ul>
<li><p>If the expressions
<nobr>are <a href="eql.htm">eql</a></nobr>.</p></li>
<li><p>If two strings
<nobr>are <a href="string-equal-s.htm.htm">string=</a></nobr>.</p></li>
<li><p>If the two <a href="../reference/car.htm">car</a>s in conses are
'equal' and the two <a href="../reference/cdr.htm">cdr</a>s in
conses <nobr>are 'equal'</nobr>.</p></li>
</ul>
<p>In all other cases 'equal'
<nobr>returns <a href="nil.htm">NIL</a></nobr>. Note that arrays are only
'equal' if they <nobr>are <a href="eq.htm">eq</a></nobr>.</p>
<p>A way to view 'equal' is that if 'expr1' and 'expr2' were printed
<nobr>[via <a href="print.htm">print</a></nobr> <nobr>or
<a href="princ.htm">princ</a>]</nobr> <nobr>and they</nobr> look the same,
then 'equal' will <nobr>return <a href="t.htm"> T </a></nobr>.</p>
<h2>Examples</h2>
<pre class="example">
(equal 'a 'a) => T
(equal 1 1) => T
(equal 1 1.0) => NIL <font color="#008844">; different number types</font>
(equal 1.0 1.0) => T
(equal "a" "a") => T
(equal '(a b) '(a b)) => T
(equal 'a 34) => NIL
(setq a '(a b)) <font color="#008844">; set value of A to (A B)</font>
(setq b a) <font color="#008844">; set B to point to A's value</font>
(setq c '(a b)) <font color="#008844">; set value of C to different (A B)</font>
(equal a b) => T
(equal a c) => T
(equal '(a b) '(A B)) => T
(equal '(a b) '(c d)) => NIL
(equal "a" "A") => NIL
(equal "abc" "abcD") => NIL
</pre>
<p>See also <a href="eq.htm">eq</a>, <a href="eql.htm">eql</a>,
<nobr><a href="../examples/common-lisp/equalp.htm">cl:equalp</a></nobr>.</p>
<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> |
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</body></html>
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