1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Function get</title> 6<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="../variant/reference.html#header.boost.variant.get_hpp" title="Header <boost/variant/get.hpp>"> 10<link rel="prev" href="strict_get.html" title="Function strict_get"> 11<link rel="next" href="bad_polymorphic_get.html" title="Class bad_polymorphic_get"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> 16<td 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class="refentrytitle">Function get</span></h2> 30<p>boost::get — Retrieves a value of a specified type from a given 31 <code class="computeroutput"><a class="link" href="variant.html" title="Class template variant">variant</a></code>.</p> 32</div> 33<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 34<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../variant/reference.html#header.boost.variant.get_hpp" title="Header <boost/variant/get.hpp>">boost/variant/get.hpp</a>> 35 36</span> 37<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> 38 <span class="identifier">U</span> <span class="special">*</span> <span class="identifier">get</span><span class="special">(</span><a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">*</span> operand<span class="special">)</span><span class="special">;</span> 39<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> 40 <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">*</span> <span class="identifier">get</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">*</span> operand<span class="special">)</span><span class="special">;</span> 41<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> 42 <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">get</span><span class="special">(</span><a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">&</span> operand<span class="special">)</span><span class="special">;</span> 43<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> 44 <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">get</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">&</span> operand<span class="special">)</span><span class="special">;</span> 45<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> 46 <span class="identifier">U</span> <span class="special">&&</span> <span class="identifier">get</span><span class="special">(</span><a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">&&</span> operand<span class="special">)</span><span class="special">;</span></pre></div> 47<div class="refsect1"> 48<a name="id-1.3.46.5.10.6.4"></a><h2>Description</h2> 49<p>Evaluates to <code class="computeroutput"><a class="link" href="strict_get.html" title="Function strict_get">strict_get</a></code> if <code class="computeroutput">BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT</code> 50 is not defined. If <code class="computeroutput">BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT</code> 51 is defined then evaluates to <code class="computeroutput"><a class="link" href="relaxed_get.html" title="Function relaxed_get">relaxed_get</a></code>. </p> 52<p><span class="bold"><strong>Recomendation</strong></span>: Use 53 <code class="computeroutput"><a class="link" href="get.html" title="Function get">get</a></code> in new code without defining 54 <code class="computeroutput">BOOST_VARIANT_USE_RELAXED_GET_BY_DEFAULT</code>. In that way <code class="computeroutput"><a class="link" href="get.html" title="Function get">get</a></code> 55 provides more compile time checks and its behavior is closer to <code class="computeroutput">std::get</code> 56 from C++ Standard Library.</p> 57</div> 58</div> 59<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 60<td align="left"></td> 61<td align="right"><div class="copyright-footer">Copyright © 2002, 2003 Eric Friedman, Itay Maman<br>Copyright © 2014-2020 Antony Polukhin<p>Distributed under the Boost Software License, Version 1.0. 62 (See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at 63 <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 64 </p> 65</div></td> 66</tr></table> 67<hr> 68<div class="spirit-nav"> 69<a accesskey="p" href="strict_get.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../variant/reference.html#header.boost.variant.get_hpp"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="bad_polymorphic_get.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> 70</div> 71</body> 72</html> 73
