120 lines
9.3 KiB
HTML
120 lines
9.3 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::move_iterator<Iter>::operator[]</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_iterator_move_iterator_operator_at skin-cppreference2 action-view cpp-page-template cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::move_iterator<Iter>::</span>operator[]</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-iterator.html">iterator</a>‎ | <a href="cpp-iterator-move_iterator.html">move iterator</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<div class="t-page-template" style="">
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<p></p>
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</div>
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dcl t-since-cxx11 t-until-cxx17">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*unspecified*/</span> operator<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span> difference_type n <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
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<span class="t-mark-rev t-until-cxx17">(C++17 前)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx17">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*unspecified*/</span> operator<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span> difference_type n <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tbody>
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</table>
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<p>返回在指定相相对位置的引用。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>n</td>
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<td>-</td>
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<td>相对于当前位置的位置。</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>到在相对位置元素的右值引用,即 <span class="t-rev-inl t-until-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>base<span class="br0">(</span><span class="br0">)</span><span class="br0">[</span>n<span class="br0">]</span><span class="br0">)</span></span></span></span> <span><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></span></span><span class="t-rev-inl t-since-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">iter_move</span><span class="br0">(</span>base<span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> n<span class="br0">)</span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> 。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iomanip></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <iterator></span>
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<span class="co2">#include <list></span>
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<span class="co2">#include <string></span>
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<span class="co2">#include <vector></span>
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<span class="kw4">void</span> print<span class="br0">(</span><span class="kw4">auto</span> rem, <span class="kw4">auto</span> <span class="kw4">const</span><span class="sy3">&</span> v<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> rem<span class="sy4">;</span> <span class="kw4">auto</span> <span class="kw4">const</span><span class="sy3">&</span> e <span class="sy4">:</span> v<span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> quoted<span class="br0">(</span>e<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy1">></span> p<span class="br0">{</span><span class="st0">"alpha"</span>, <span class="st0">"beta"</span>, <span class="st0">"gamma"</span>, <span class="st0">"delta"</span><span class="br0">}</span>, q<span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"1) p: "</span>, p<span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-iterator-move_iterator.html"><span class="kw659">std::<span class="me2">move_iterator</span></span></a> it<span class="br0">{</span>p.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span>size_t t<span class="br0">{</span>0U<span class="br0">}</span><span class="sy4">;</span> t <span class="sy3">!</span><span class="sy1">=</span> p.<span class="me1">size</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="sy2">++</span>t<span class="br0">)</span> <span class="br0">{</span>
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q.<span class="me1">emplace_back</span><span class="br0">(</span> it<span class="br0">[</span>t<span class="br0">]</span> <span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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print<span class="br0">(</span><span class="st0">"2) p: "</span>, p<span class="br0">)</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"3) q: "</span>, q<span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-container-list.html"><span class="kw1275">std::<span class="me2">list</span></span></a> l<span class="br0">{</span><span class="nu0">1</span>,<span class="nu0">2</span>,<span class="nu0">3</span><span class="br0">}</span><span class="sy4">;</span>
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<a href="cpp-iterator-move_iterator.html"><span class="kw659">std::<span class="me2">move_iterator</span></span></a> it2<span class="br0">{</span>l.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="co1">// it2[1] = 13; // 编译错误 ~ 底层迭代器不实现随机访问迭代器</span>
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<span class="co1">// *it2 = 999; // 编译错误:以右值为左值</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出:</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">1) p: "alpha" "beta" "gamma" "delta"
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2) p: "" "" "" ""
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3) q: "alpha" "beta" "gamma" "delta"</pre></div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<div class="t-dsc-member-div">
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<div><a href="cpp-iterator-move_iterator-operator*.html"><span class="t-lines"><span>operator*</span><span>operator-></span></span></a></div>
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<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 class="t-mark-rev t-deprecated-cxx20">(C++20 中弃用)</span></span></span></div>
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</div>
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</td>
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<td>访问被指向的元素<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</body>
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