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<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="the_boost_algorithm_library.Misc.hex"></a><a class="link" href="hex.html" title="hex">hex</a>
</h3></div></div></div>
<p>
The header file <code class="computeroutput"><span class="char">'boost/algorithm/hex.hpp'</span></code>
contains three variants each of two algorithms, <code class="computeroutput"><span class="identifier">hex</span></code>
and <code class="computeroutput"><span class="identifier">unhex</span></code>. They are inverse
algorithms; that is, one undoes the effort of the other. <code class="computeroutput"><span class="identifier">hex</span></code>
takes a sequence of values, and turns them into hexadecimal characters.
<code class="computeroutput"><span class="identifier">unhex</span></code> takes a sequence of
hexadecimal characters, and outputs a sequence of values.
</p>
<p>
<code class="computeroutput"><span class="identifier">hex</span></code> and <code class="computeroutput"><span class="identifier">unhex</span></code>
come from MySQL, where they are used in database queries and stored procedures.
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h0"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.interface"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.interface">interface</a>
</h5>
<p>
The function <code class="computeroutput"><span class="identifier">hex</span></code> takes a
sequence of values and writes hexadecimal characters. There are three different
interfaces, differing only in how the input sequence is specified.
</p>
<p>
The first one takes an iterator pair. The second one takes a pointer to the
start of a zero-terminated sequence, such as a c string, and the third takes
a range as defined by the Boost.Range library.
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">InputIterator</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span>
<span class="identifier">OutputIterator</span> <span class="identifier">hex</span> <span class="special">(</span> <span class="identifier">InputIterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">InputIterator</span> <span class="identifier">last</span><span class="special">,</span> <span class="identifier">OutputIterator</span> <span class="identifier">out</span> <span class="special">);</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span>
<span class="identifier">OutputIterator</span> <span class="identifier">hex</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span><span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">OutputIterator</span> <span class="identifier">out</span> <span class="special">);</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Range</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span>
<span class="identifier">OutputIterator</span> <span class="identifier">hex</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Range</span> <span class="special">&</span><span class="identifier">r</span><span class="special">,</span> <span class="identifier">OutputIterator</span> <span class="identifier">out</span> <span class="special">);</span>
</pre>
<p>
</p>
<p>
<code class="computeroutput"><span class="identifier">hex</span></code> writes only values in
the range '0'..'9' and 'A'..'F', but is not limited to character output.
The output iterator could refer to a wstring, or a vector of integers, or
any other integral type.
</p>
<p>
The function <code class="computeroutput"><span class="identifier">unhex</span></code> takes
the output of <code class="computeroutput"><span class="identifier">hex</span></code> and turns
it back into a sequence of values.
</p>
<p>
The input parameters for the different variations of <code class="computeroutput"><span class="identifier">unhex</span></code>
are the same as <code class="computeroutput"><span class="identifier">hex</span></code>.
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">InputIterator</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span>
<span class="identifier">OutputIterator</span> <span class="identifier">unhex</span> <span class="special">(</span> <span class="identifier">InputIterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">InputIterator</span> <span class="identifier">last</span><span class="special">,</span> <span class="identifier">OutputIterator</span> <span class="identifier">out</span> <span class="special">);</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span>
<span class="identifier">OutputIterator</span> <span class="identifier">unhex</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span><span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">OutputIterator</span> <span class="identifier">out</span> <span class="special">);</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Range</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputIterator</span><span class="special">></span>
<span class="identifier">OutputIterator</span> <span class="identifier">unhex</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Range</span> <span class="special">&</span><span class="identifier">r</span><span class="special">,</span> <span class="identifier">OutputIterator</span> <span class="identifier">out</span> <span class="special">);</span>
</pre>
<p>
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h1"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.error_handling"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.error_handling">Error
Handling</a>
</h5>
<p>
The header 'hex.hpp' defines three exception classes:
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">hex_decode_error</span><span class="special">:</span> <span class="keyword">virtual</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">exception</span><span class="special">,</span> <span class="keyword">virtual</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception</span> <span class="special">{};</span>
<span class="keyword">struct</span> <span class="identifier">not_enough_input</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">hex_decode_error</span><span class="special">;</span>
<span class="keyword">struct</span> <span class="identifier">non_hex_input</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">hex_decode_error</span><span class="special">;</span>
</pre>
<p>
</p>
<p>
If the input to <code class="computeroutput"><span class="identifier">unhex</span></code> does
not contain an "even number" of hex digits, then an exception of
type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">algorithm</span><span class="special">::</span><span class="identifier">not_enough_input</span></code> is thrown.
</p>
<p>
If the input to <code class="computeroutput"><span class="identifier">unhex</span></code> contains
any non-hexadecimal characters, then an exception of type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">algorithm</span><span class="special">::</span><span class="identifier">non_hex_input</span></code>
is thrown.
</p>
<p>
If you want to catch all the decoding errors, you can catch exceptions of
type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">algorithm</span><span class="special">::</span><span class="identifier">hex_decode_error</span></code>.
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h2"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.examples"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.examples">Examples</a>
</h5>
<p>
Assuming that <code class="computeroutput"><span class="identifier">out</span></code> is an iterator
that accepts <code class="computeroutput"><span class="keyword">char</span></code> values, and
<code class="computeroutput"><span class="identifier">wout</span></code> accepts <code class="computeroutput"><span class="keyword">wchar_t</span></code> values (and that sizeof ( wchar_t
) == 2)
</p>
<p>
</p>
<pre class="programlisting"><span class="identifier">hex</span> <span class="special">(</span> <span class="string">"abcdef"</span><span class="special">,</span> <span class="identifier">out</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"616263646566"</span>
<span class="identifier">hex</span> <span class="special">(</span> <span class="string">"32"</span><span class="special">,</span> <span class="identifier">out</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"3332"</span>
<span class="identifier">hex</span> <span class="special">(</span> <span class="string">"abcdef"</span><span class="special">,</span> <span class="identifier">wout</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"006100620063006400650066"</span>
<span class="identifier">hex</span> <span class="special">(</span> <span class="string">"32"</span><span class="special">,</span> <span class="identifier">wout</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"00330032"</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"616263646566"</span><span class="special">,</span> <span class="identifier">out</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"abcdef"</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"3332"</span><span class="special">,</span> <span class="identifier">out</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"32"</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"616263646566"</span><span class="special">,</span> <span class="identifier">wout</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"\6162\6364\6566"</span> <span class="special">(</span> <span class="identifier">i</span><span class="special">.</span><span class="identifier">e</span><span class="special">,</span> <span class="identifier">a</span> <span class="number">3</span> <span class="identifier">character</span> <span class="identifier">string</span> <span class="special">)</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"3332"</span><span class="special">,</span> <span class="identifier">wout</span> <span class="special">)</span> <span class="special">--></span> <span class="string">"\3233"</span> <span class="special">(</span> <span class="identifier">U</span><span class="special">+</span><span class="number">3332</span><span class="special">,</span> <span class="identifier">SQUARE</span> <span class="identifier">HUARADDO</span> <span class="special">)</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"3"</span><span class="special">,</span> <span class="identifier">out</span> <span class="special">)</span> <span class="special">--></span> <span class="identifier">Error</span> <span class="special">-</span> <span class="keyword">not</span> <span class="identifier">enough</span> <span class="identifier">input</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"32"</span><span class="special">,</span> <span class="identifier">wout</span> <span class="special">)</span> <span class="special">--></span> <span class="identifier">Error</span> <span class="special">-</span> <span class="keyword">not</span> <span class="identifier">enough</span> <span class="identifier">input</span>
<span class="identifier">unhex</span> <span class="special">(</span> <span class="string">"ACEG"</span><span class="special">,</span> <span class="identifier">out</span> <span class="special">)</span> <span class="special">--></span> <span class="identifier">Error</span> <span class="special">-</span> <span class="identifier">non</span><span class="special">-</span><span class="identifier">hex</span> <span class="identifier">input</span>
</pre>
<p>
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h3"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.iterator_requirements"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.iterator_requirements">Iterator
Requirements</a>
</h5>
<p>
<code class="computeroutput"><span class="identifier">hex</span></code> and <code class="computeroutput"><span class="identifier">unhex</span></code>
work on all iterator types.
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h4"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.complexity"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.complexity">Complexity</a>
</h5>
<p>
All of the variants of <code class="computeroutput"><span class="identifier">hex</span></code>
and <code class="computeroutput"><span class="identifier">unhex</span></code> run in <span class="emphasis"><em>O(N)</em></span>
(linear) time; that is, that is, they process each element in the input sequence
once.
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h5"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.exception_safety"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.exception_safety">Exception
Safety</a>
</h5>
<p>
All of the variants of <code class="computeroutput"><span class="identifier">hex</span></code>
and <code class="computeroutput"><span class="identifier">unhex</span></code> take their parameters
by value or const reference, and do not depend upon any global state. Therefore,
all the routines in this file provide the strong exception guarantee. However,
when working on input iterators, if an exception is thrown, the input iterators
will not be reset to their original values (i.e, the characters read from
the iterator cannot be un-read)
</p>
<h5>
<a name="the_boost_algorithm_library.Misc.hex.h6"></a>
<span><a name="the_boost_algorithm_library.Misc.hex.notes"></a></span><a class="link" href="hex.html#the_boost_algorithm_library.Misc.hex.notes">Notes</a>
</h5>
<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
<code class="computeroutput"><span class="identifier">hex</span></code> and <code class="computeroutput"><span class="identifier">unhex</span></code> both do nothing when passed empty
ranges.
</li></ul></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2010-2012 Marshall Clow<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
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