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<div class="refentry" title="Class tribool">
<a name="boost.logic.tribool"></a><div class="titlepage"></div>
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<h2><span class="refentrytitle">Class tribool</span></h2>
<p>boost::logic::tribool — A 3-state boolean type. </p>
</div>
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="emphasis"><em>// In header: <<a class="link" href="../../tribool/reference.html#header.boost.logic.tribool_hpp" title="Header <boost/logic/tribool.hpp>">boost/logic/tribool.hpp</a>>
</em></span>
<span class="bold"><strong>class</strong></span> <a class="link" href="tribool.html" title="Class tribool">tribool</a> {
<span class="bold"><strong>public</strong></span>:
<span class="bold"><strong>enum</strong></span> <a class="link" href="tribool/value_t.html" title="Type value_t">value_t</a>;
<span class="emphasis"><em>// <a class="link" href="tribool.html#boost.logic.triboolconstruct-copy-destruct">construct/copy/destruct</a></em></span>
<a class="link" href="tribool.html#id650926-bb">tribool</a>();
<a class="link" href="tribool.html#id650937-bb">tribool</a>(<span class="bold"><strong>bool</strong></span>);
<a class="link" href="tribool.html#id650959-bb">tribool</a>(indeterminate_keyword_t);
<span class="emphasis"><em>// <a class="link" href="tribool.html#id1125813-bb">public member functions</a></em></span>
<a class="link" href="tribool.html#id1125816-bb"><span class="bold"><strong>operator</strong></span> safe_bool</a>() <span class="bold"><strong>const</strong></span>;
<span class="type"><span class="bold"><strong>enum</strong></span> boost::logic::tribool::value_t</span> value;
};</pre></div>
<div class="refsect1" title="Description">
<a name="id1864938"></a><h2>Description</h2>
<p>3-state boolean values are either true, false, or indeterminate. </p>
<div class="refsect2" title="tribool public construct/copy/destruct">
<a name="id1864945"></a><h3>
<a name="boost.logic.triboolconstruct-copy-destruct"></a><code class="computeroutput">tribool</code>
public
construct/copy/destruct</h3>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<pre class="literallayout"><a name="id650926-bb"></a>tribool();</pre>
<p>Construct a new 3-state boolean value with the value 'false'.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr></tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><a name="id650937-bb"></a>tribool(<span class="bold"><strong>bool</strong></span> value);</pre>
<p>Construct a new 3-state boolean value with the given boolean value, which may be <code class="computeroutput">true</code> or <code class="computeroutput">false</code>.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr></tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><a name="id650959-bb"></a>tribool(indeterminate_keyword_t);</pre>
<p>Construct a new 3-state boolean value with an indeterminate value.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr></tbody>
</table></div>
</li>
</ol></div>
</div>
<div class="refsect2" title="tribool public member functions">
<a name="id1865076"></a><h3>
<a name="id1125813-bb"></a><code class="computeroutput">tribool</code> public member functions</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<pre class="literallayout"><a name="id1125816-bb"></a><span class="bold"><strong>operator</strong></span> safe_bool() <span class="bold"><strong>const</strong></span>;</pre>
<p>Use a 3-state boolean in a boolean context. Will evaluate true in a boolean context only when the 3-state boolean is definitely true.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term">Returns:</span></p></td>
<td><p>true if the 3-state boolean is true, false otherwise </p></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr>
</tbody>
</table></div>
</li></ol></div>
</div>
</div>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 2002-2004 Douglas Gregor<p>Use, modification and distribution is subject to the Boost
Software License, Version 1.0. (See accompanying file
<code class="filename">LICENSE_1_0.txt</code> 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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