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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../piecewise_construct.html" title="cpp/utility/piecewise construct"><span class="t-lines"><span>piecewise_construct</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../integer_sequence.html" title="cpp/utility/integer sequence"><span class="t-lines"><span>integer_sequence</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Swap, forward and move</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../../algorithm/swap.html" title="cpp/algorithm/swap"><span class="t-lines"><span>swap</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../exchange.html" title="cpp/utility/exchange"><span class="t-lines"><span>exchange</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../forward.html" title="cpp/utility/forward"><span class="t-lines"><span>forward</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../move.html" title="cpp/utility/move"><span class="t-lines"><span>move</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../move_if_noexcept.html" title="cpp/utility/move if noexcept"><span class="t-lines"><span>move_if_noexcept</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Type operations</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../declval.html" title="cpp/utility/declval"><span class="t-lines"><span>declval</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="../as_const.html" title="cpp/utility/as const"><span class="t-lines"><span>as_const</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div></div></td></tr>
</table></div><div><span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/utility/navbar_content&action=edit">[edit]</a></span></div></div></div></div><div class="t-navbar-sep"> </div><div class="t-navbar-head"><a href="../functional.html" title="cpp/utility/functional"> Function objects</a><div class="t-navbar-menu"><div><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv-h2"><td colspan="5"> Function wrappers </td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="function.html" title="cpp/utility/functional/function"><span class="t-lines"><span>function</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="mem_fn.html" title="cpp/utility/functional/mem fn"><span class="t-lines"><span>mem_fn</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bad_function_call.html" title="cpp/utility/functional/bad function call"><span class="t-lines"><span>bad_function_call</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="invoke.html" title="cpp/utility/functional/invoke"><span class="t-lines"><span>invoke</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Bind </td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bind.html" title="cpp/utility/functional/bind"><span class="t-lines"><span>bind</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="is_bind_expression.html" title="cpp/utility/functional/is bind expression"><span class="t-lines"><span>is_bind_expression</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="is_placeholder.html" title="cpp/utility/functional/is placeholder"><span class="t-lines"><span>is_placeholder</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="placeholders.html" title="cpp/utility/functional/placeholders"><span class="t-lines"><span>_1, _2, _3, ...</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Reference wrappers </td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="reference_wrapper.html" title="cpp/utility/functional/reference wrapper"><span class="t-lines"><span>reference_wrapper</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><strong class="selflink"><span class="t-lines"><span>ref</span><span>cref</span></span></strong></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Operator wrappers </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="plus.html" title="cpp/utility/functional/plus"><span class="t-lines"><span>plus</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="minus.html" title="cpp/utility/functional/minus"><span class="t-lines"><span>minus</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="negate.html" title="cpp/utility/functional/negate"><span class="t-lines"><span>negate</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="multiplies.html" title="cpp/utility/functional/multiplies"><span class="t-lines"><span>multiplies</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="divides.html" title="cpp/utility/functional/divides"><span class="t-lines"><span>divides</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="modulus.html" title="cpp/utility/functional/modulus"><span class="t-lines"><span>modulus</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="logical_and.html" title="cpp/utility/functional/logical and"><span class="t-lines"><span>logical_and</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="logical_or.html" title="cpp/utility/functional/logical or"><span class="t-lines"><span>logical_or</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="logical_not.html" title="cpp/utility/functional/logical not"><span class="t-lines"><span>logical_not</span></span></a></div></div></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="equal_to.html" title="cpp/utility/functional/equal to"><span class="t-lines"><span>equal_to</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="not_equal_to.html" title="cpp/utility/functional/not equal to"><span class="t-lines"><span>not_equal_to</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="greater.html" title="cpp/utility/functional/greater"><span class="t-lines"><span>greater</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="less.html" title="cpp/utility/functional/less"><span class="t-lines"><span>less</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="greater_equal.html" title="cpp/utility/functional/greater equal"><span class="t-lines"><span>greater_equal</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="less_equal.html" title="cpp/utility/functional/less equal"><span class="t-lines"><span>less_equal</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bit_and.html" title="cpp/utility/functional/bit and"><span class="t-lines"><span>bit_and</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bit_or.html" title="cpp/utility/functional/bit or"><span class="t-lines"><span>bit_or</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bit_xor.html" title="cpp/utility/functional/bit xor"><span class="t-lines"><span>bit_xor</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bit_not.html" title="cpp/utility/functional/bit not"><span class="t-lines"><span>bit_not</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span></span></div></div></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Negators </td></tr>
<tr class="t-nv-col-table"><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="unary_negate.html" title="cpp/utility/functional/unary negate"><span class="t-lines"><span>unary_negate</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="binary_negate.html" title="cpp/utility/functional/binary negate"><span class="t-lines"><span>binary_negate</span></span></a></div></div></td></tr>
</table></div></td><td><div><table class="t-nv-begin" cellpadding="0" style="">
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="not1.html" title="cpp/utility/functional/not1"><span class="t-lines"><span>not1</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="not2.html" title="cpp/utility/functional/not2"><span class="t-lines"><span>not2</span></span></a></div></div></td></tr>
</table></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Deprecated binders and adaptors </td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="unary_function.html" title="cpp/utility/functional/unary function"><span class="t-lines"><span>unary_function</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="binary_function.html" title="cpp/utility/functional/binary function"><span class="t-lines"><span>binary_function</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="ptr_fun.html" title="cpp/utility/functional/ptr fun"><span class="t-lines"><span>ptr_fun</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="pointer_to_unary_function.html" title="cpp/utility/functional/pointer to unary function"><span class="t-lines"><span>pointer_to_unary_function</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="pointer_to_binary_function.html" title="cpp/utility/functional/pointer to binary function"><span class="t-lines"><span>pointer_to_binary_function</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="mem_fun.html" title="cpp/utility/functional/mem fun"><span class="t-lines"><span>mem_fun</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="mem_fun_t.html" title="cpp/utility/functional/mem fun t"><span class="t-lines"><span>mem_fun_t</span><span>mem_fun1_t</span><span>const_mem_fun_t</span><span>const_mem_fun1_t</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="mem_fun_ref.html" title="cpp/utility/functional/mem fun ref"><span class="t-lines"><span>mem_fun_ref</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="mem_fun_ref_t.html" title="cpp/utility/functional/mem fun ref t"><span class="t-lines"><span>mem_fun_ref_t</span><span>mem_fun1_ref_t</span><span>const_mem_fun_ref_t</span><span>const_mem_fun1_ref_t</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="binder12.html" title="cpp/utility/functional/binder12"><span class="t-lines"><span>binder1st</span><span>binder2nd</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="bind12.html" title="cpp/utility/functional/bind12"><span class="t-lines"><span>bind1st</span><span>bind2nd</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span><span><span class="t-mark-rev t-until-cxx17">(until C++17)</span></span></span></div></div></td></tr>
</table></div><div><span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/utility/functional/navbar_content&action=edit">[edit]</a></span></div></div></div></div><div class="t-navbar-sep"> </div></div>
<table class="t-dcl-begin"><tbody>
<tr class="t-dsc-header">
<td> <div>Defined in header <code><a href="../../header/functional.html" title="cpp/header/functional"><functional></a></code>
</div></td>
<td></td>
<td></td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
<a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span>T<span class="sy1">></span> ref<span class="br0">(</span>T<span class="sy3">&</span> t<span class="br0">)</span><span class="sy4">;</span></span></div></td>
<td> (1) </td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> </td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
<a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span>T<span class="sy1">></span> ref<span class="br0">(</span> <a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span>T<span class="sy1">></span> t <span class="br0">)</span><span class="sy4">;</span></span></div></td>
<td> (2) </td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> </td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span> <span class="sy1"><</span><span class="kw1">class</span> T<span class="sy1">></span><br />
<span class="kw4">void</span> ref<span class="br0">(</span><span class="kw4">const</span> T<span class="sy3">&&</span><span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></div></td>
<td> (3) </td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> </td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
<a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span><span class="kw4">const</span> T<span class="sy1">></span> cref<span class="br0">(</span> <span class="kw4">const</span> T<span class="sy3">&</span> t <span class="br0">)</span><span class="sy4">;</span></span></div></td>
<td> (4) </td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> </td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
<a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span><span class="kw4">const</span> T<span class="sy1">></span> cref<span class="br0">(</span> <a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span>T<span class="sy1">></span> t <span class="br0">)</span><span class="sy4">;</span></span></div></td>
<td> (5) </td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> </td>
</tr>
<tr class="t-dcl t-since-cxx11">
<td> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span> <span class="sy1"><</span><span class="kw1">class</span> T<span class="sy1">></span><br />
<span class="kw4">void</span> cref<span class="br0">(</span><span class="kw4">const</span> T<span class="sy3">&&</span><span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></div></td>
<td> (6) </td>
<td> <span class="t-mark-rev t-since-cxx11">(since C++11)</span> </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
</tbody></table>
<p>Function templates <code>ref</code> and <code>cref</code> are helper functions that generate an object of type <span class="t-lc">std::reference_wrapper</span>, using <a href="../../language/template_argument_deduction.html" title="cpp/language/template argument deduction">template argument deduction</a> to determine the template argument of the result.
</p>
<table id="toc" class="toc"><tr><td><div id="toctitle"><h2>Contents</h2></div>
<ul>
<li class="toclevel-1 tocsection-1"><a href="ref.html#Parameters"><span class="tocnumber">1</span> <span class="toctext">Parameters</span></a></li>
<li class="toclevel-1 tocsection-2"><a href="ref.html#Return_value"><span class="tocnumber">2</span> <span class="toctext">Return value</span></a></li>
<li class="toclevel-1 tocsection-3"><a href="ref.html#Exceptions"><span class="tocnumber">3</span> <span class="toctext">Exceptions</span></a></li>
<li class="toclevel-1 tocsection-4"><a href="ref.html#Example"><span class="tocnumber">4</span> <span class="toctext">Example</span></a></li>
<li class="toclevel-1 tocsection-5"><a href="ref.html#See_also"><span class="tocnumber">5</span> <span class="toctext">See also</span></a></li>
</ul>
</td></tr></table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/ref&action=edit&section=1" title="Edit section: Parameters">edit</a>]</span> <span class="mw-headline" id="Parameters">Parameters</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td> t
</td>
<td> -
</td>
<td> lvalue reference to object that needs to be wrapped or an instance of <span class="t-lc">std::reference_wrapper</span>
</td></tr></table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/ref&action=edit&section=2" title="Edit section: Return value">edit</a>]</span> <span class="mw-headline" id="Return_value">Return value</span></h3>
<div class="t-li1"><span class="t-li">1)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="br0">(</span>t<span class="br0">)</span></span></span></div>
<div class="t-li1"><span class="t-li">2)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">ref<span class="br0">(</span>t.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span></div>
<div class="t-li1"><span class="t-li">4)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="reference_wrapper.html"><span class="kw933">std::<span class="me2">reference_wrapper</span></span></a><span class="sy1"><</span><span class="kw4">const</span> T<span class="sy1">></span><span class="br0">(</span>t<span class="br0">)</span></span></span></div>
<div class="t-li1"><span class="t-li">5)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp">cref<span class="br0">(</span>t.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span></div>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/ref&action=edit&section=3" title="Edit section: Exceptions">edit</a>]</span> <span class="mw-headline" id="Exceptions">Exceptions</span></h3>
<div class="t-noexcept-inline"><a href="../../language/noexcept_spec.html" title="cpp/language/noexcept spec"><tt>noexcept</tt></a> specification:  <div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span></span></span></div>  </div>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/ref&action=edit&section=4" title="Edit section: Example">edit</a>]</span> <span class="mw-headline" id="Example">Example</span></h3>
<div class="t-example"><div class="t-example-live-link"><div class="coliru-btn coliru-btn-run-init">Run this code</div></div>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="co2">#include <functional></span>
<span class="co2">#include <iostream></span>
 
<span class="kw4">void</span> f<span class="br0">(</span><span class="kw4">int</span><span class="sy3">&</span> n1, <span class="kw4">int</span><span class="sy3">&</span> n2, <span class="kw4">const</span> <span class="kw4">int</span><span class="sy3">&</span> n3<span class="br0">)</span>
<span class="br0">{</span>
<a href="../../io/cout.html"><span class="kw1479">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"In function: "</span> <span class="sy1"><<</span> n1 <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> n2 <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> n3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
<span class="sy2">++</span>n1<span class="sy4">;</span> <span class="co1">// increments the copy of n1 stored in the function object</span>
<span class="sy2">++</span>n2<span class="sy4">;</span> <span class="co1">// increments the main()'s n2</span>
<span class="co1">// ++n3; // compile error</span>
<span class="br0">}</span>
 
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">int</span> n1 <span class="sy1">=</span> <span class="nu0">1</span>, n2 <span class="sy1">=</span> <span class="nu0">2</span>, n3 <span class="sy1">=</span> <span class="nu0">3</span><span class="sy4">;</span>
<a href="function.html"><span class="kw930">std::<span class="me2">function</span></span></a><span class="sy1"><</span><span class="kw4">void</span><span class="br0">(</span><span class="br0">)</span><span class="sy1">></span> bound_f <span class="sy1">=</span> <a href="bind.html"><span class="kw925">std::<span class="me2">bind</span></span></a><span class="br0">(</span>f, n1, std<span class="sy4">::</span><span class="me2">ref</span><span class="br0">(</span>n2<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">cref</span><span class="br0">(</span>n3<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
n1 <span class="sy1">=</span> <span class="nu0">10</span><span class="sy4">;</span>
n2 <span class="sy1">=</span> <span class="nu0">11</span><span class="sy4">;</span>
n3 <span class="sy1">=</span> <span class="nu0">12</span><span class="sy4">;</span>
<a href="../../io/cout.html"><span class="kw1479">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Before function: "</span> <span class="sy1"><<</span> n1 <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> n2 <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> n3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
bound_f<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<a href="../../io/cout.html"><span class="kw1479">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"After function: "</span> <span class="sy1"><<</span> n1 <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> n2 <span class="sy1"><<</span> <span class="st0">' '</span> <span class="sy1"><<</span> n3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div></div>
<p>Output:
</p>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="text source-text"><pre class="de1">Before function: 10 11 12
In function: 1 11 12
After function: 10 12 12</pre></div></div>
</div>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/ref&action=edit&section=5" title="Edit section: See also">edit</a>]</span> <span class="mw-headline" id="See_also">See also</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td> <div class="t-dsc-member-div"><div><a href="reference_wrapper.html" title="cpp/utility/functional/reference wrapper"> <span class="t-lines"><span>reference_wrapper</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div></div>
</td>
<td> <a href="../../concept/CopyConstructible.html" title="cpp/concept/CopyConstructible"><code>CopyConstructible</code></a> and <a href="../../concept/CopyAssignable.html" title="cpp/concept/CopyAssignable"><code>CopyAssignable</code></a> reference wrapper <br /> <span class="t-mark">(class template)</span> <span class="editsection noprint plainlinks" title="Edit this template"><a rel="nofollow" class="external text" href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/utility/functional/dsc_reference_wrapper&action=edit">[edit]</a></span>
</td></tr>
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