254 lines
23 KiB
HTML
254 lines
23 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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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>std::filesystem::path::path</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_path_path skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::path::</span>path</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="br0">(</span><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>(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="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>(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="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>(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">path<span class="br0">(</span> string_type<span class="sy3">&&</span> source, format fmt <span class="sy1">=</span> auto_format <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 t-since-cxx17">
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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="br0">(</span> <span class="kw4">const</span> Source<span class="sy3">&</span> source, format fmt <span class="sy1">=</span> auto_format <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(5)</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> InputIt <span class="sy1">></span><br />
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path<span class="br0">(</span> InputIt first, InputIt last, format fmt <span class="sy1">=</span> auto_format <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(6)</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="br0">(</span> <span class="kw4">const</span> Source<span class="sy3">&</span> source, <span class="kw4">const</span> <a href="cpp-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a><span class="sy3">&</span> loc, format fmt <span class="sy1">=</span> auto_format <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(7)</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> InputIt <span class="sy1">></span><br />
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path<span class="br0">(</span> InputIt first, InputIt last, <span class="kw4">const</span> <a href="cpp-locale-locale.html"><span class="kw1894">std::<span class="me2">locale</span></span></a><span class="sy3">&</span> loc, format fmt <span class="sy1">=</span> auto_format <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(8)</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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<p>构造新的 <code>path</code> 对象。</p>
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<div class="t-li1"><span class="t-li">1)</span> 构造空路径。</div>
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<div class="t-li1"><span class="t-li">2)</span> 复制构造函数。构造一个路径，其原生与通用格式的路径名均与 <code>p</code> 相同</div>
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<div class="t-li1"><span class="t-li">3)</span> 移动构造函数。构造一个路径，其原生与通用格式的路径名均与 <code>p</code> 相同， <code>p</code> 留在合法而未指定的状态。</div>
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<div class="t-li1"><span class="t-li">4-6)</span> 从 <code>source</code> <span class="t-v">(4,5)</span> 提供的字符序列构造路径（按 <code>fmt</code> 的指定转译格式），源可以是一个指向空终值字符/宽字符序列的指针或输入迭代器、 <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> ，或作为一对输入迭代器 [<code>first</code>, <code>last</code>) 提供 <span class="t-v">(6)</span> 。允许字符类型 <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> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span></span></span> ，而且原生字符集的转换方法依赖于 <code>source</code> 所用的字符类型
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<dl>
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<dd>
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<ul>
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<li>若源字符类型是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> ，则源的编码假定为原生窄字符编码（故在 POSIX 系统上不用转换）</li>
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</ul>
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</dd>
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</dl>
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<table class="t-rev-begin">
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<tr class="t-rev t-since-cxx20">
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<td>
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<dl>
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<dd>
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<ul>
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<li>若源字符类型是 <span class="t-c"><span class="mw-geshi cpp source-cpp">char8_t</span></span> ，则使用从 UTF-8 到原生文件系统编码的转换。</li>
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</ul>
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</dd>
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</dl>
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</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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</table>
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<dl>
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<dd>
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<ul>
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<li>若源字符类型是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char16_t</span></span></span> ，则使用从 UTF-16 到原生文件系统编码的转换。</li>
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<li>若源字符类型是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char32_t</span></span></span> ，则使用从 UTF-32 到原生文件系统编码的转换。</li>
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<li>若源字符类型是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span></span></span> ，则输入被假定为原生宽字符编码（故在 Windos 上不用转换）</li>
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</ul>
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</dd>
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</dl>
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</div>
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<div class="t-li1"><span class="t-li">7-8)</span> 从 <code>source</code> <span class="t-v">(7)</span> 提供的从字符序列构造路径（按 <code>fmt</code> 的指定转译格式），源可以是指向空终止字符序列的指针或输入迭代器、 <span class="t-lc"><a href="cpp-string-basic_string.html">std::string</a></span> 、 <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::basic_string_view</a></span> ，或由一对输入迭代器 [<code>first</code>, <code>last</code>) <span class="t-v">(8)</span> 所代表。仅允许的字符类型是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> 。用 <code>loc</code> 进行字符编码转换。若 <code>value_type</code> 是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">wchar_t</span></span></span> ，则使用 <code>loc</code> 的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-locale-codecvt.html"><span class="kw1939">std::<span class="me2">codecvt</span></span></a><span class="sy1"><</span><span class="kw4">wchar_t</span>, <span class="kw4">char</span>, <a href="cpp-string-multibyte-mbstate_t.html"><span class="kw1179">std::<span class="me2">mbstate_t</span></span></a><span class="sy1">></span></span></span> 平面从宽字符转换。否则，首先用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-locale-codecvt.html"><span class="kw1939">std::<span class="me2">codecvt</span></span></a><span class="sy1"><</span><span class="kw4">wchar_t</span>, <span class="kw4">char</span>, <a href="cpp-string-multibyte-mbstate_t.html"><span class="kw1179">std::<span class="me2">mbstate_t</span></span></a><span class="sy1">></span></span></span> 平面转换到宽字符，再用 <code>loc</code> 的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-locale-codecvt.html"><span class="kw1939">std::<span class="me2">codecvt</span></span></a><span class="sy1"><</span><span class="kw4">wchar_t</span>,value_type<span class="sy1">></span></span></span> 平面转换到文件系统原生字符类型。</div>
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<p><span class="t-v">(5)</span> 与 <span class="t-v">(7)</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>要复制的路径</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> ，指向空终止字符串的指针，或拥有字符 value_type 并指向空终止字符序列的的输入迭代器（对于重载 <span class="t-v">(6)</span> 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> ）</td>
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</tr>
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<tr class="t-par">
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<td>first, last</td>
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<td>-</td>
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<td>一对指定字符序列的<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">老式输入迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyInputIterator)</span></a></td>
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</tr>
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<tr class="t-par">
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<td>fmt</td>
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<td>-</td>
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<td><a href="cpp-filesystem-path-format.html"><tt>path::format</tt></a> 类型的枚举项，指定路径名格式如何转译</td>
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</tr>
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<tr class="t-par">
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<td>loc</td>
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<td>-</td>
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<td>定义编码转换所用的本地环境</td>
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</tr>
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<tr class="t-par-hitem">
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<td colspan="3">类型要求</td>
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</tr>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>InputIt</code> 必须满足<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">老式输入迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyInputIterator)</span></a> 的要求。</td>
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</tr>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>InputIt</code> 的 value_type 必须是字符类型 <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">wchar_t</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char16_t</span></span></span> 及 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char32_t</span></span></span> 之一，以使用重载 <span class="t-v">(6)</span></td>
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</tr>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>InputIt</code> 的 value_type 必须是 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> ，以使用 <span class="t-v">(8)</span></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<div class="t-li1"><span class="t-li">2, 4-8)</span> 可能抛出实现定义的异常。</div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<table class="t-rev-begin">
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<tr class="t-rev t-until-cxx20">
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<td>
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<p>关于从 Unicode 字符串生成可移植路径名，见 <a href="cpp-filesystem-path-u8path.html"><code>u8path</code></a> 。</p>
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</td>
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<td><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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</tr>
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<tr class="t-rev t-since-cxx20">
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<td>
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<p>源为 <span class="t-c"><span class="mw-geshi cpp source-cpp">char8_t</span></span> 的序列时， <code>path</code> 构造函数支持从 UTF-8 字符串创建。</p>
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</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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</table>
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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 <iostream></span>
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<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> p1 <span class="sy1">=</span> <span class="st0">"/usr/lib/sendmail.cf"</span><span class="sy4">;</span> <span class="co1">// 可移植格式</span>
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fs<span class="sy4">::</span><span class="me2">path</span> p2 <span class="sy1">=</span> <span class="st0">"C:<span class="es1">\\</span>users<span class="es1">\\</span>abcdef<span class="es1">\\</span>AppData<span class="es1">\\</span>Local<span class="es1">\\</span>Temp<span class="es1">\\</span>"</span><span class="sy4">;</span> <span class="co1">// 原生格式</span>
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fs<span class="sy4">::</span><span class="me2">path</span> p3 <span class="sy1">=</span> L<span class="st0">"D:/猫.txt"</span><span class="sy4">;</span> <span class="co1">// 宽字符串</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">"p1 = "</span> <span class="sy1"><<</span> p1 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"p2 = "</span> <span class="sy1"><<</span> p2 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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|
<span class="sy1"><<</span> <span class="st0">"p3 = "</span> <span class="sy1"><<</span> p3 <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></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">p1 = "/usr/lib/sendmail.cf"
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p2 = "C:\users\abcdef\AppData\Local\Temp\"
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p3 = "D:/猫.txt"</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>
|
|
<th>DR</th>
|
|
<th>应用于</th>
|
|
<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>
|
|
<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>
|
|
<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">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">
|
|
<div><a href="cpp-filesystem-path-u8path.html"><span class="t-lines"><span>u8path</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span><span class="t-mark-rev t-deprecated-cxx20">(C++20 中弃用)</span></span></span></div>
|
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</div>
|
|
</td>
|
|
<td>从 UTF-8 编码的源创建 <code>path</code><br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</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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