145 lines
14 KiB
HTML
145 lines
14 KiB
HTML
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<title>std::filesystem::relative, std::filesystem::proximate</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_relative 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::</span>relative, <span style="font-size:0.7em; line-height:130%">std::filesystem::</span>proximate</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></span></div>
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<div>定义于头文件 <code><a href="cpp-header-filesystem.html"><filesystem></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp">path relative<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br />
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<a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span> ec<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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<div><span class="mw-geshi cpp source-cpp">path relative<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br /></span>
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<p> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> base <span class="sy1">=</span> <a href="cpp-filesystem-current_path.html"><span class="kw2271">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">current_path</span></span></a><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span><br />
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path relative<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br />
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<span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> base,<br /></p>
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<a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span> ec<span class="br0">)</span><span class="sy4">;</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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<div><span class="mw-geshi cpp source-cpp">path proximate<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br />
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<a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span> ec<span class="br0">)</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-cxx17">(C++17 起)</span></td>
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<tr class="t-dcl t-since-cxx17">
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<div><span class="mw-geshi cpp source-cpp">path proximate<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br /></span>
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<p> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> base <span class="sy1">=</span> <a href="cpp-filesystem-current_path.html"><span class="kw2271">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">current_path</span></span></a><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span><br />
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path proximate<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br />
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<span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> base,<br /></p>
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<a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span> ec<span class="br0">)</span><span class="sy4">;</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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<div class="t-li1"><span class="t-li">1)</span> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">relative<span class="br0">(</span>p, current_path<span class="br0">(</span><span class="br0">)</span>, ec<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">2)</span> 返回设为相对于 <code>base</code> 的 <code>p</code> 。在其他处理前解析符号链接并正常化 <code>p</code> 与 <code>base</code> 。等效于返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">weakly_canonical<span class="br0">(</span>p<span class="br0">)</span>.<span class="me1">lexically_relative</span><span class="br0">(</span>weakly_canonical<span class="br0">(</span>base<span class="br0">)</span><span class="br0">)</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">weakly_canonical<span class="br0">(</span>p, ec<span class="br0">)</span>.<span class="me1">lexically_relative</span><span class="br0">(</span>weakly_canonical<span class="br0">(</span>base, ec<span class="br0">)</span><span class="br0">)</span></span></span> ，除了错误码形式在首次错误出现时返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">path<span class="br0">(</span><span class="br0">)</span></span></span> ，若有错误。</div>
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<div class="t-li1"><span class="t-li">3)</span> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">proximate<span class="br0">(</span>p, current_path<span class="br0">(</span><span class="br0">)</span>, ec<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">4)</span> 等效于返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">weakly_canonical<span class="br0">(</span>p<span class="br0">)</span>.<span class="me1">lexically_proximate</span><span class="br0">(</span>weakly_canonical<span class="br0">(</span>base<span class="br0">)</span><span class="br0">)</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">weakly_canonical<span class="br0">(</span>p, ec<span class="br0">)</span>.<span class="me1">lexically_proximate</span><span class="br0">(</span>weakly_canonical<span class="br0">(</span>base, ec<span class="br0">)</span><span class="br0">)</span></span></span> ，除了错误码形式在首次错误出现时返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">path<span class="br0">(</span><span class="br0">)</span></span></span> ，若有错误。</div>
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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>既存路径</td>
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</tr>
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<tr class="t-par">
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<td>base</td>
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<td>-</td>
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<td>基路径， <code>p</code> 将相对于它被设为相对/接近</td>
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</tr>
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<tr class="t-par">
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<td>ec</td>
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<td>-</td>
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<td>存储错误状态的错误码</td>
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</tr>
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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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<div class="t-li1"><span class="t-li">1)</span> 设为相对于 base 的 p 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 设为接近 base 的 p 。</div>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>不接受 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span></span></span> 参数的重载在底层 OS API 错误时抛出 <a href="cpp-filesystem-filesystem_error.html"><tt>filesystem_error</tt></a> ，以第一 path 参数 <code>p</code>，第二 path 参数 <code>base</code> 和作为错误码参数的 OS 错误码构造。若 OS API 调用失败，则接受 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span></span></span> 参数的重载设置该参数为 OS API 错误码，而若不出现错误则执行 <span class="t-c"><span class="mw-geshi cpp source-cpp">ec.<span class="me1">clear</span><span class="br0">(</span><span class="br0">)</span></span></span> 。若内存分配失败，则任何不标记为 <code>noexcept</code> 的重载可能抛出 <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></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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<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
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<td class="mbox-empty-cell"></td>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</td>
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</tr>
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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-filesystem-path.html"><span class="t-lines"><span>path</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>表示路径<br />
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<span class="t-mark">(类)</span></td>
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</tr>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-filesystem-absolute.html"><span class="t-lines"><span>absolute</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>组成一个绝对路径<br />
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<span class="t-mark">(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">
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<div><a href="cpp-filesystem-canonical.html"><span class="t-lines"><span>canonical</span><span>weakly_canonical</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>组成一个规范路径<br />
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<span class="t-mark">(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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