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<h3 class="section">3.1 Built-in Data Types</h3>
<p><a name="index-data-types_002c-built_002din-173"></a><a name="index-built_002din-data-types-174"></a>
The standard built-in data types are real and complex scalars and
matrices, ranges, character strings, a data structure type, and cell
arrays. Additional built-in data types may be added in future versions.
If you need a specialized data type that is not currently provided as a
built-in type, you are encouraged to write your own user-defined data
type and contribute it for distribution in a future release of Octave.
<p>The data type of a variable can be determined and changed through the
use of the following functions.
<!-- ov-class.cc -->
<p><a name="doc_002dclass"></a>
<div class="defun">
— Built-in Function: <b>class</b> (<var>expr</var>)<var><a name="index-class-175"></a></var><br>
— Built-in Function: <b>class</b> (<var>s, id</var>)<var><a name="index-class-176"></a></var><br>
— Built-in Function: <b>class</b> (<var>s, id, p, <small class="dots">...</small></var>)<var><a name="index-class-177"></a></var><br>
<blockquote><p>Return the class of the expression <var>expr</var> or create a class with
fields from structure <var>s</var> and name (string) <var>id</var>. Additional
arguments name a list of parent classes from which the new class is
derived.
</p></blockquote></div>
<!-- ./general/isa.m -->
<p><a name="doc_002disa"></a>
<div class="defun">
— Function File: <b>isa</b> (<var>x, class</var>)<var><a name="index-isa-178"></a></var><br>
<blockquote><p>Return true if <var>x</var> is a value from the class <var>class</var>.
</p></blockquote></div>
<!-- ./miscellaneous/cast.m -->
<p><a name="doc_002dcast"></a>
<div class="defun">
— Function File: <b>cast</b> (<var>val, type</var>)<var><a name="index-cast-179"></a></var><br>
<blockquote><p>Convert <var>val</var> to data type <var>type</var>.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dint8.html#doc_002dint8">int8</a>, <a href="doc_002duint8.html#doc_002duint8">uint8</a>, <a href="doc_002dint16.html#doc_002dint16">int16</a>, <a href="doc_002duint16.html#doc_002duint16">uint16</a>, <a href="doc_002dint32.html#doc_002dint32">int32</a>, <a href="doc_002duint32.html#doc_002duint32">uint32</a>, <a href="doc_002dint64.html#doc_002dint64">int64</a>, <a href="doc_002duint64.html#doc_002duint64">uint64</a>, <a href="doc_002ddouble.html#doc_002ddouble">double</a>.
</p></blockquote></div>
<!-- ./DLD-FUNCTIONS/typecast.cc -->
<p><a name="doc_002dtypecast"></a>
<div class="defun">
— Loadable Function: <b>typecast</b> (<var>x, type</var>)<var><a name="index-typecast-180"></a></var><br>
<blockquote><p>Convert from one datatype to another without changing the underlying
data. The argument <var>type</var> defines the type of the return argument
and must be one of 'uint8', 'uint16', 'uint32', 'uint64', 'int8', 'int16',
'int32', 'int64', 'single' or 'double'.
<p>An example of the use of typecast on a little-endian machine is
<pre class="example"> <var>x</var> = uint16 ([1, 65535]);
typecast (<var>x</var>, 'uint8')
⇒ [ 0, 1, 255, 255]
</pre>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dcast.html#doc_002dcast">cast</a>, <a href="doc_002dswapbytes.html#doc_002dswapbytes">swapbytes</a>.
</p></blockquote></div>
<!-- ./miscellaneous/swapbytes.m -->
<p><a name="doc_002dswapbytes"></a>
<div class="defun">
— Function File: <b>swapbytes</b> (<var>x</var>)<var><a name="index-swapbytes-181"></a></var><br>
<blockquote><p>Swaps the byte order on values, converting from little endian to big
endian and vice versa. For example
<pre class="example"> swapbytes (uint16 (1:4))
⇒ [ 256 512 768 1024]
</pre>
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dtypecast.html#doc_002dtypecast">typecast</a>, <a href="doc_002dcast.html#doc_002dcast">cast</a>.
</p></blockquote></div>
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