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Previous: <a rel="previous" accesskey="p" href="String-Conversions.html#String-Conversions">String Conversions</a>,
Up: <a rel="up" accesskey="u" href="Strings.html#Strings">Strings</a>
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<h3 class="section">5.7 Character Class Functions</h3>
<p>Octave also provides the following character class test functions
patterned after the functions in the standard C library. They all
operate on string arrays and return matrices of zeros and ones.
Elements that are nonzero indicate that the condition was true for the
corresponding character in the string array. For example,
<pre class="example"> isalpha ("!Q@WERT^Y&")
⇒ [ 0, 1, 0, 1, 1, 1, 1, 0, 1, 0 ]
</pre>
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<p><a name="doc_002disalnum"></a>
<div class="defun">
— Mapping Function: <b>isalnum</b> (<var>s</var>)<var><a name="index-isalnum-353"></a></var><br>
<blockquote><p>Return 1 for characters that are letters or digits (<code>isalpha
(</code><var>s</var><code>)</code> or <code>isdigit (</code><var>s</var><code>)</code> is true).
</p></blockquote></div>
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<p><a name="doc_002disalpha"></a>
<div class="defun">
— Mapping Function: <b>isalpha</b> (<var>s</var>)<var><a name="index-isalpha-354"></a></var><br>
— Mapping Function: <b>isletter</b> (<var>s</var>)<var><a name="index-isletter-355"></a></var><br>
<blockquote><p>Return true for characters that are letters (<code>isupper (</code><var>s</var><code>)</code>
or <code>islower (</code><var>s</var><code>)</code> is true).
</p></blockquote></div>
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<p><a name="doc_002disascii"></a>
<div class="defun">
— Mapping Function: <b>isascii</b> (<var>s</var>)<var><a name="index-isascii-356"></a></var><br>
<blockquote><p>Return 1 for characters that are ASCII (in the range 0 to 127 decimal).
</p></blockquote></div>
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<p><a name="doc_002discntrl"></a>
<div class="defun">
— Mapping Function: <b>iscntrl</b> (<var>s</var>)<var><a name="index-iscntrl-357"></a></var><br>
<blockquote><p>Return 1 for control characters.
</p></blockquote></div>
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<p><a name="doc_002disdigit"></a>
<div class="defun">
— Mapping Function: <b>isdigit</b> (<var>s</var>)<var><a name="index-isdigit-358"></a></var><br>
<blockquote><p>Return 1 for characters that are decimal digits.
</p></blockquote></div>
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<p><a name="doc_002disgraph"></a>
<div class="defun">
— Mapping Function: <b>isgraph</b> (<var>s</var>)<var><a name="index-isgraph-359"></a></var><br>
<blockquote><p>Return 1 for printable characters (but not the space character).
</p></blockquote></div>
<!-- ./strings/isletter.m -->
<p><a name="doc_002disletter"></a>
<div class="defun">
— Function File: <b>isletter</b> (<var>s</var>)<var><a name="index-isletter-360"></a></var><br>
<blockquote><p>Returns true if <var>s</var> is a letter, false otherwise.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002disalpha.html#doc_002disalpha">isalpha</a>.
</p></blockquote></div>
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<p><a name="doc_002dislower"></a>
<div class="defun">
— Mapping Function: <b>islower</b> (<var>s</var>)<var><a name="index-islower-361"></a></var><br>
<blockquote><p>Return 1 for characters that are lower case letters.
</p></blockquote></div>
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<p><a name="doc_002disprint"></a>
<div class="defun">
— Mapping Function: <b>isprint</b> (<var>s</var>)<var><a name="index-isprint-362"></a></var><br>
<blockquote><p>Return 1 for printable characters (including the space character).
</p></blockquote></div>
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<p><a name="doc_002dispunct"></a>
<div class="defun">
— Mapping Function: <b>ispunct</b> (<var>s</var>)<var><a name="index-ispunct-363"></a></var><br>
<blockquote><p>Return 1 for punctuation characters.
</p></blockquote></div>
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<p><a name="doc_002disspace"></a>
<div class="defun">
— Mapping Function: <b>isspace</b> (<var>s</var>)<var><a name="index-isspace-364"></a></var><br>
<blockquote><p>Return 1 for whitespace characters (space, formfeed, newline,
carriage return, tab, and vertical tab).
</p></blockquote></div>
<!-- mappers.cc -->
<p><a name="doc_002disupper"></a>
<div class="defun">
— Mapping Function: <b>isupper</b> (<var>s</var>)<var><a name="index-isupper-365"></a></var><br>
<blockquote><p>Return 1 for upper case letters.
</p></blockquote></div>
<!-- mappers.cc -->
<p><a name="doc_002disxdigit"></a>
<div class="defun">
— Mapping Function: <b>isxdigit</b> (<var>s</var>)<var><a name="index-isxdigit-366"></a></var><br>
<blockquote><p>Return 1 for characters that are hexadecimal digits.
</p></blockquote></div>
<!-- ./strings/isstrprop.m -->
<p><a name="doc_002disstrprop"></a>
<div class="defun">
— Function File: <b>isstrprop</b> (<var>str, pred</var>)<var><a name="index-isstrprop-367"></a></var><br>
<blockquote><p>Test character string properties. For example,
<pre class="example"> isstrprop ("abc123", "alpha")
⇒ [1, 1, 1, 0, 0, 0]
</pre>
<p>If <var>str</var> is a cell array, <code>isstrpop</code> is applied recursively
to each element of the cell array.
<p>Numeric arrays are converted to character strings.
<p>The second argument <var>pred</var> may be one of
<dl>
<dt><code>"alpha"</code><dd>True for characters that are alphabetic
<br><dt><code>"alnum"</code><dt><code>"alphanum"</code><dd>True for characters that are alphabetic or digits.
<br><dt><code>"ascii"</code><dd>True for characters that are in the range of ASCII encoding.
<br><dt><code>"cntrl"</code><dd>True for control characters.
<br><dt><code>"digit"</code><dd>True for decimal digits.
<br><dt><code>"graph"</code><dt><code>"graphic"</code><dd>True for printing characters except space.
<br><dt><code>"lower"</code><dd>True for lower-case letters.
<br><dt><code>"print"</code><dd>True for printing characters including space.
<br><dt><code>"punct"</code><dd>True for printing characters except space or letter or digit.
<br><dt><code>"space"</code><dt><code>"wspace"</code><dd>True for whitespace characters (space, formfeed, newline, carriage
return, tab, vertical tab).
<br><dt><code>"upper"</code><dd>True for upper-case letters.
<br><dt><code>"xdigit"</code><dd>True for hexadecimal digits.
</dl>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002disalnum.html#doc_002disalnum">isalnum</a>, <a href="doc_002disalpha.html#doc_002disalpha">isalpha</a>, <a href="doc_002disascii.html#doc_002disascii">isascii</a>, <a href="doc_002discntrl.html#doc_002discntrl">iscntrl</a>, <a href="doc_002disdigit.html#doc_002disdigit">isdigit</a>, <a href="doc_002disgraph.html#doc_002disgraph">isgraph</a>, <a href="doc_002dislower.html#doc_002dislower">islower</a>, <a href="doc_002disprint.html#doc_002disprint">isprint</a>, <a href="doc_002dispunct.html#doc_002dispunct">ispunct</a>, <a href="doc_002disspace.html#doc_002disspace">isspace</a>, <a href="doc_002disupper.html#doc_002disupper">isupper</a>, <a href="doc_002disxdigit.html#doc_002disxdigit">isxdigit</a>.
</p></blockquote></div>
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