269 lines
22 KiB
HTML
269 lines
22 KiB
HTML
<!DOCTYPE html>
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<title>std::ranges::swap_ranges, std::ranges::swap_ranges_result</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_algorithm_ranges_swap_ranges skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span>swap_ranges, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>swap_ranges_result</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-algorithm.html">algorithm</a>‎ | <a href="cpp-algorithm-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-algorithm.html"><algorithm></a></code></div>
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<div>调用签名</div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> std<span class="sy4">::</span><span class="me2">input_iterator</span> I1, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I1<span class="sy1">></span> S1,<br /></span>
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<p> std<span class="sy4">::</span><span class="me2">input_iterator</span> I2, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I2<span class="sy1">></span> S2 <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">indirectly_swappable</span><span class="sy1"><</span>I1, I2<span class="sy1">></span><br />
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<span class="kw4">constexpr</span> swap_ranges_result<span class="sy1"><</span>I1, I2<span class="sy1">></span><br /></p>
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swap_ranges<span class="br0">(</span> I1 first1, S1 last1, I2 first2, S2 last2 <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> ranges<span class="sy4">::</span><span class="me2">input_range</span> R1, ranges<span class="sy4">::</span><span class="me2">input_range</span> R2 <span class="sy1">></span><br /></span>
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<p>requires std<span class="sy4">::</span><span class="me2">indirectly_swappable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>, ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R2<span class="sy1">>></span><br />
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<span class="kw4">constexpr</span> swap_ranges_result<span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>,<br />
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ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R2<span class="sy1">>></span><br /></p>
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swap_ranges<span class="br0">(</span> R1<span class="sy3">&&</span> r1, R2<span class="sy3">&&</span> r2 <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div>辅助类型</div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> I1, <span class="kw1">class</span> I2 <span class="sy1">></span><br />
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<span class="kw1">using</span> swap_ranges_result <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">in_in_result</span><span class="sy1"><</span>I1, I2<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 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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<div class="t-li1"><span class="t-li">1)</span> 在第一范围 <code>[first1, first1 + M)</code> 与第二范围 <code>[first2, first2 + M)</code> 间交换元素，其中 <span class="t-c"><span class="mw-geshi cpp source-cpp">M <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">min</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first1, last1<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first2, last2<span class="br0">)</span><span class="br0">)</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li"></span> 范围 <code>[first1, last1)</code> 与 <code>[first2, last2)</code> 必须不重叠。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ，但以 <code>r1</code> 为第一范围并以 <code>r2</code> 为第二范围，如同以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r1<span class="br0">)</span></span></span> 为 <code>first1</code> ，以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r1<span class="br0">)</span></span></span> 为 <code>last1</code> ，以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r2<span class="br0">)</span></span></span> 为 <code>first2</code> ，并以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r2<span class="br0">)</span></span></span> 为 <code>last2</code> 。</div>
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<p>此页面上描述的仿函数实体是 <i>niebloid</i> ，即：</p>
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<ul>
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<li>调用它们中的任何一者时不可指定显式模板实参。</li>
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<li>它们无一对<a href="cpp-language-adl.html">实参依赖查找</a>可见。</li>
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<li>在<a href="cpp-language-unqualified_lookup.html">通常无限定查找</a>寻找函数调用运算符左侧的名称找到它们之一时，它禁止<a href="cpp-language-adl.html">实参依赖查找</a>。</li>
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</ul>
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<p>实际上，它们能以函数对象，或以某些特殊编译器扩展实现。</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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<td>first1, last1</td>
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<td>-</td>
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<td>要交换的第一范围</td>
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</tr>
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<tr class="t-par">
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<td>first2, last2</td>
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<td>-</td>
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<td>要交换的第二范围</td>
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</tr>
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<tr class="t-par">
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<td>r1</td>
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<td>-</td>
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<td>要交换的第一范围</td>
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</tr>
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<tr class="t-par">
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<td>r2</td>
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<td>-</td>
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<td>要交换的第二范围</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><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu0">1</span><span class="br0">{</span>first1 <span class="sy2">+</span> M, first2 <span class="sy2">+</span> M<span class="br0">}</span></span></span> 。</p>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
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<p>准确交换 <span class="t-c"><span class="mw-geshi cpp source-cpp">M</span></span> 次。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>实现（例如 <a rel="nofollow" class="external text" href="https://github.com/microsoft/STL/blob/main/stl/src/vector_algorithms.cpp">MSVC STL</a> ）可能在迭代器类型实现 <a href="cpp-iterator-contiguous_iterator.html"><code>contiguous_iterator</code></a> ，并且交换其值类型不调用非平凡的特殊成员函数或 <a href="cpp-language-adl.html">ADL</a> 所找到的 <code>swap</code> 时启用向量化。</p>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">可能的实现</span></h3>
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<table class="eq-fun-cpp-table">
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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="kw1">struct</span> swap_ranges_fn <span class="br0">{</span>
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<span class="kw1">template</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">input_iterator</span> I1, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I1<span class="sy1">></span> S1,
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std<span class="sy4">::</span><span class="me2">input_iterator</span> I2, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I2<span class="sy1">></span> S2<span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">indirectly_swappable</span><span class="sy1"><</span>I1, I2<span class="sy1">></span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">swap_ranges_result</span><span class="sy1"><</span>I1, I2<span class="sy1">></span>
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operator<span class="br0">(</span><span class="br0">)</span> <span class="br0">(</span> I1 first1, S1 last1, I2 first2, S2 last2 <span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="sy4">;</span> <span class="sy3">!</span><span class="br0">(</span>first1 <span class="sy1">==</span> last1 or first2 <span class="sy1">==</span> last2<span class="br0">)</span><span class="sy4">;</span> <span class="sy2">++</span>first1, <span class="sy2">++</span>first2<span class="br0">)</span>
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ranges<span class="sy4">::</span><span class="me2">iter_swap</span><span class="br0">(</span>first1, first2<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="br0">{</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first1<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first2<span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">template</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">input_range</span> R1, ranges<span class="sy4">::</span><span class="me2">input_range</span> R2<span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">indirectly_swappable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>, ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R2<span class="sy1">>></span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">swap_ranges_result</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R1<span class="sy1">></span>,
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ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R2<span class="sy1">>></span>
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operator<span class="br0">(</span><span class="br0">)</span> <span class="br0">(</span> R1<span class="sy3">&&</span> r1, R2<span class="sy3">&&</span> r2 <span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">return</span> <span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r1<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r1<span class="br0">)</span>,
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ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r2<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r2<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span><span class="sy4">;</span>
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<span class="kw1">inline</span> <span class="kw4">constexpr</span> swap_ranges_fn swap_ranges<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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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 <algorithm></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <list></span>
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<span class="co2">#include <string_view></span>
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<span class="co2">#include <vector></span>
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<span class="kw4">auto</span> print<span class="br0">(</span><a href="cpp-string-basic_string_view.html"><span class="kw1248">std::<span class="me2">string_view</span></span></a> name, <span class="kw4">auto</span> <span class="kw4">const</span><span class="sy3">&</span> seq, <a href="cpp-string-basic_string_view.html"><span class="kw1248">std::<span class="me2">string_view</span></span></a> term <span class="sy1">=</span> <span class="st0">"<span class="es1">\n</span>"</span><span class="br0">)</span> <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> name <span class="sy1"><<</span> <span class="st0">" : "</span><span class="sy4">;</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> elem <span class="sy4">:</span> seq<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> elem <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> term<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><span class="kw4">char</span><span class="sy1">></span> p <span class="br0">{</span><span class="st0">'A'</span>, <span class="st0">'B'</span>, <span class="st0">'C'</span>, <span class="st0">'D'</span>, <span class="st0">'E'</span><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><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span> q <span class="br0">{</span><span class="st0">'1'</span>, <span class="st0">'2'</span>, <span class="st0">'3'</span>, <span class="st0">'4'</span>, <span class="st0">'5'</span>, <span class="st0">'6'</span><span class="br0">}</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"p"</span>, p<span class="br0">)</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"q"</span>, q, <span class="st0">"<span class="es1">\n</span><span class="es1">\n</span>"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 交换 p[0, 2) 与 q[1, 3):</span>
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std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">swap_ranges</span><span class="br0">(</span>p.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>,
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p.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> <span class="nu0">4</span>,
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std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">next</span><span class="br0">(</span>q.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">1</span><span class="br0">)</span>,
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std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">next</span><span class="br0">(</span>q.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, <span class="nu0">3</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"p"</span>, p<span class="br0">)</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"q"</span>, q, <span class="st0">"<span class="es1">\n</span><span class="es1">\n</span>"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 交换 p[0, 5) 与 q[0, 5):</span>
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std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">swap_ranges</span><span class="br0">(</span>p, q<span class="br0">)</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"p"</span>, p<span class="br0">)</span><span class="sy4">;</span>
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print<span class="br0">(</span><span class="st0">"q"</span>, q<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>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">p : A B C D E
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q : 1 2 3 4 5 6
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p : 2 3 C D E
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q : 1 A B 4 5 6
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p : 1 A B 4 5
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q : 2 3 C D E 6</pre></div>
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</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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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-iterator-ranges-iter_swap.html"><span class="t-lines"><span>iter_swap</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
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</div>
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</td>
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<td>交换两个可解引用对象所引用的值<br />
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<span class="t-mark">(定制点对象)</span></td>
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</tr>
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<tr class="t-dsc">
|
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<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-utility-ranges-swap.html"><span class="t-lines"><span>ranges::swap</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
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</div>
|
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</td>
|
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<td>交换两个对象的值<br />
|
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<span class="t-mark">(定制点对象)</span></td>
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</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-swap_ranges.html"><span class="t-lines"><span>swap_ranges</span></span></a></div>
|
|
</div>
|
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</td>
|
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<td>交换两个范围的元素<br />
|
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<span class="t-mark">(函数模板)</span></td>
|
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</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-iter_swap.html"><span class="t-lines"><span>iter_swap</span></span></a></div>
|
|
</div>
|
|
</td>
|
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<td>交换两个迭代器所指向的元素<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-swap.html"><span class="t-lines"><span>swap</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>交换两个对象的值<br />
|
|
<span class="t-mark">(函数模板)</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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</div>
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</div>
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</div>
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</body>
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</html>
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