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<html><head><title>XLISP hash</title></head>
<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>hash</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>xlbfun.c, xlsym.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(hash <i>name table-size</i>)</dt>
<dd><i>name</i> - a symbol or string expression<br>
<i>table-size</i> - an integer expression<br>
returns - the hash index as an integer value</dd>
</dl>
<h2>Description</h2>
<p>The 'hash' function computes and returns an integer index for a given
symbol 'name' and a given size of hash table 'table-size'. The intention is
for 'hash' to be used with tables made by
<a href="make-array.htm">make-array</a> and accessed by
<a href="aref.htm">aref</a>.</p>
<h2>Examples</h2>
<pre class="example">
(hash "zzzz" 1000) <font color="#008844">; returns index 322</font>
(hash "ZZZZ" 1000) <font color="#008844">; returns index 626</font>
(hash 'ZZZZ 1000) <font color="#008844">; returns index 626</font>
(hash "hiho" 1000) <font color="#008844">; returns index 519</font>
(hash 'hiho 1000) <font color="#008844">; returns index 143</font>
(hash "abcd" 1000) <font color="#008844">; returns index 72</font>
<font color="#008844">;; create a function to look inside *OBARRAY* and</font>
<font color="#008844">;; look for a specific symbol - returns a list</font>
(defun lookin (sym)
(aref *obarray*
(hash sym (length *obarray*))))
(lookin 'caar) <font color="#008844">; returns the hash table entry</font>
<font color="#008844">; (ZEROP CDDDDR CAAR HASH)</font>
</pre>
<p><b>Note:</b> This is a useful function for creating and accessing tables.
It is also useful for looking inside of XLISP's own symbol table
<a href="global-obarray.htm">*obarray*</a>.</p>
<p>See the
<a href="../manual/xlisp-man-013.htm#hash">hash</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
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<a href="../manual/contents.htm">Contents</a> |
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