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<html><head><title>XLISP digit-char-p</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>digit-char-p</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>xlstr.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(digit-char-p <i>char</i>)</dt>
<dd><i>char</i> - a character expression<br>
returns - the digit weight if character is a digit,
<a href="nil.htm">NIL</a> otherwise</dd>
</dl>
<h2>Description</h2>
<p>The 'digit-char-p' predicate function checks if the 'char' expression is
a numeric digit. If 'char' is numeric digit, the equivalent integer value
is returned, otherwise a <a href="nil.htm">NIL</a> is
returned. Decimal digits are '0' [ASCII decimal <nobr>value 48]</nobr>
through '9' [ASCII decimal <nobr>value 57].</nobr></p>
<h2>Examples</h2>
<pre class="example">
(digit-char-p #\0) <font color="#008844">; returns 0</font>
(digit-char-p #\9) <font color="#008844">; returns 9</font>
(digit-char-p #\A) <font color="#008844">; returns NIL</font>
(digit-char-p #\a) <font color="#008844">; returns NIL</font>
(digit-char-p #\.) <font color="#008844">; returns NIL</font>
(digit-char-p #\-) <font color="#008844">; returns NIL</font>
(digit-char-p #\+) <font color="#008844">; returns NIL</font>
</pre>
<p><b>Note:</b> Other non-digit characters used in numbers are NOT included:
plus [+], minus [-], exponent <nobr>[e or E]</nobr> and decimal point
[.].</p>
<p><b>Common Lisp:</b> Common Lisp supports the use of an optional radix
parameter. This option specifies numeric base. This allows the
'digit-char-p' to function properly for hexadecimal digits [for example].
Common LISP supports up to base 36 radix systems. XLISP does not support
this radix parameter.</p>
<p>See the
<a href="../manual/xlisp-man-026.htm#digit-char-p">digit-char-p</a>
predicate 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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