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<td><h2>Safe Numerics</h2></td>
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<div class="titlepage"><div><div><h3 class="title">
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<a name="safe_numerics.checked_integer_arithmetic"></a>Checked Integer Arithmetic</h3></div></div></div>
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<div class="toc"><dl class="toc">
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50878042656">Synopsis</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877811808">Description</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877810464">Type requirements</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877808368">Complexity</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877807216">Header</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877805568">Example of use</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877792848">Notes</a></span></dt>
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<dt><span class="section"><a href="checked_integer_arithmetic.html#idm50877791280">See Also</a></span></dt>
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</dl></div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50878042656"></a>Synopsis</h4></div></div></div>
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<pre class="programlisting"><span class="comment">// safe casting on primitive types</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">cast</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// safe addition on primitive types</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">add</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// safe subtraction on primitive types</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">subtract</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// safe multiplication on primitive types</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">multiply</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// safe division on unsafe types</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">divide</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">divide_automatic</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// safe modulus on unsafe types</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">modulus</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// left shift</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">left_shift</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// right shift</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">right_shift</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="comment">// bitwise operations</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">bitwise_or</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">bitwise_and</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">U</span><span class="special">></span>
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<span class="keyword">constexpr</span> <span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span>
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<span class="identifier">checked</span><span class="special">::</span><span class="identifier">bitwise_xor</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> <span class="identifier">t</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">u</span><span class="special">)</span><span class="special">;</span>
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</pre>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877811808"></a>Description</h4></div></div></div>
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<p>Perform binary operations on arithmetic types. Return either a valid
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result or an error code. Under no circumstances should an incorrect result
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be returned.</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877810464"></a>Type requirements</h4></div></div></div>
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<p>All template parameters of the functions must model <a class="link" href="integer.html" title="Integer<T>">Integer</a> type requirements.</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877808368"></a>Complexity</h4></div></div></div>
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<p>Each function performs one and only one arithmetic operation</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877807216"></a>Header</h4></div></div></div>
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<p><code class="computeroutput">#include "checked.hpp" </code></p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877805568"></a>Example of use</h4></div></div></div>
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<p>[A code fragment that illustrates how to use the function.]</p>
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<pre class="programlisting"><span class="preprocessor">#include</span> <span class="string">"checked.hpp"</span>
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<span class="identifier">checked_result</span><span class="special"><</span><span class="identifier">result_base_type</span><span class="special">></span> <span class="identifier">r</span> <span class="special">=</span> <span class="identifier">checked</span><span class="special">::</span><span class="identifier">multiply</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span><span class="special">(</span><span class="number">24</span><span class="special">,</span> <span class="number">42</span><span class="special">)</span><span class="special">;</span>
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</pre>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877792848"></a>Notes</h4></div></div></div>
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<p>Some compilers have command line switches (e.g. -ftrapv) which
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enable special behavior such erroneous integer operations are detected at
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run time. The library has been implemented in such a way that these
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facilities are not used. It's possible they might be helpful in particular
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environment. These could be be exploited by re-implementing some functions
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in this library.</p>
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</div>
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<div class="section">
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<div class="titlepage"><div><div><h4 class="title">
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<a name="idm50877791280"></a>See Also</h4></div></div></div>
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<p><a class="link" href="checked_result.html" title="checked_result<typename R>">checked_result<typename
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R></a></p>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2012 Robert Ramey<p><a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">Subject to Boost
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Software License</a></p>
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