139 lines
11 KiB
HTML
139 lines
11 KiB
HTML
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<title>std::filesystem::path::operator=</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_path_operator 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::filesystem::path::</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-filesystem.html">filesystem</a>‎ | <a href="cpp-filesystem-path.html">path</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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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dcl t-since-cxx17">
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<td>
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<div><span class="mw-geshi cpp source-cpp">path<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> path<span class="sy3">&</span> p <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</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 t-since-cxx17">
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<td>
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<div><span class="mw-geshi cpp source-cpp">path<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> path<span class="sy3">&&</span> p <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</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 t-since-cxx17">
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<td>
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<div><span class="mw-geshi cpp source-cpp">path<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span>string_type<span class="sy3">&&</span> source<span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</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 t-since-cxx17">
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<td>
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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> Source <span class="sy1">></span><br />
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path<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> Source<span class="sy3">&</span> source <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(4)</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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</tr>
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</tbody>
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</table>
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<div class="t-li1"><span class="t-li">1)</span> 以原生和通用格式均与 <code>p</code> 相同的路径名替换 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的内容。</div>
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<div class="t-li1"><span class="t-li">2)</span> 以原生和通用格式均与 <code>p</code> 相同的路径名替换 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的内容，可能使用移动语义： <code>p</code> 留在合法但未指定的状态。</div>
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<div class="t-li1"><span class="t-li">3)</span> 以从受检测格式的 <code>source</code> 构造的新 path 值替换 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的内容。 <code>source</code> 留合法但未指定的状态。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">assign<span class="br0">(</span>source<span class="br0">)</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">4)</span> 从受检测格式的 <code>source</code> ，如同以 <a href="cpp-filesystem-path-path.html">path 构造函数</a>的重载 <span class="t-v">(4)</span> 构造的新 path 值替换 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的内容。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">assign<span class="br0">(</span>source<span class="br0">)</span></span></span> 。</div>
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<p><span class="t-v">(4)</span> 仅若 <code>Source</code> 与 <code>path</code> 不是同一类型，而且：</p>
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<ul>
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<li><code>Source</code> 是 <span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> 或 <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::basic_string_view</a></span> 的特化，或</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1"><</span><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>Source</span><span class="mw-geshi cpp source-cpp"><span class="sy1">>></span><span class="sy4">::</span><span class="me2">value_type</span></span></span> 合法并代表可能有 const 限定的编码字符类型（ <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> 、 <span class="t-rev-inl t-since-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp">char8_t</span></span> 、</span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char16_t</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char32_t</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span></span></span> ）</li>
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</ul>
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<p>才参与重载决议</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>p</td>
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<td>-</td>
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<td>要赋值的路径</td>
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</tr>
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<tr class="t-par">
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<td>source</td>
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<td>-</td>
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<td><span class="t-lc"><a href="cpp-string-basic_string.html">std::basic_string</a></span> 、 <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::basic_string_view</a></span> 、指向空终止字符/宽字符串的指针，或指向空终止字符/宽字符序列的输入迭代器。字符类型必须是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> <span class="t-rev-inl t-since-cxx20"><span>、<span class="t-c"><span class="mw-geshi cpp source-cpp">char8_t</span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char16_t</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char32_t</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span></span></span> 之一</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="sy2">*</span>this</span></span></p>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</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 <filesystem></span>
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<span class="kw1">namespace</span> fs <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">;</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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fs<span class="sy4">::</span><span class="me2">path</span> p <span class="sy1">=</span> <span class="st0">"C:/users/abcdef/AppData/Local"</span><span class="sy4">;</span>
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p <span class="sy1">=</span> p <span class="sy2">/</span> <span class="st0">"Temp"</span><span class="sy4">;</span> <span class="co1">// 移动赋值</span>
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<span class="kw4">const</span> <span class="kw4">wchar_t</span><span class="sy2">*</span> wstr <span class="sy1">=</span> L<span class="st0">"D:/猫.txt"</span><span class="sy4">;</span>
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p <span class="sy1">=</span> wstr<span class="sy4">;</span> <span class="co1">// 从源赋值</span>
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<span class="br0">}</span></pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
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<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
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<table class="dsctable" style="font-size:0.8em">
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<tr>
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<th>DR</th>
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<th>应用于</th>
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<th>出版时的行为</th>
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<th>正确行为</th>
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</tr>
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<tr>
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<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3244">LWG 3244</a></td>
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<td>C++17</td>
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<td>缺失 <code>Source</code> 不能为 <code>path</code> 的制约</td>
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<td>已添加</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85_2">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-filesystem-path-assign.html"><span class="t-lines"><span>assign</span></span></a></div>
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</div>
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</td>
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<td>赋值内容<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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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-filesystem-path-path.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造一个 <code>path</code><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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</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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