253 lines
22 KiB
HTML
253 lines
22 KiB
HTML
<!DOCTYPE html>
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<title>std::filesystem::directory_entry::status, std::filesystem::directory_entry::symlink_status</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_directory_entry_status 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::directory_entry::</span>status, <span style="font-size:0.7em; line-height:130%">std::filesystem::directory_entry::</span>symlink_status</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-directory_entry.html">directory entry</a></span></div>
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<td>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-filesystem-file_status.html"><span class="kw2206">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">file_status</span></span></a> status<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span><br />
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<a href="cpp-filesystem-file_status.html"><span class="kw2206">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">file_status</span></span></a> status<span class="br0">(</span> <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="kw4">const</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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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-filesystem-file_status.html"><span class="kw2206">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">file_status</span></span></a> symlink_status<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span><br />
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<a href="cpp-filesystem-file_status.html"><span class="kw2206">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">file_status</span></span></a> symlink_status<span class="br0">(</span> <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="kw4">const</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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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-sep">
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<td></td>
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<td></td>
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<td></td>
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<div class="t-li1"><span class="t-li">1)</span> 返回入口的状态,如同用 <a href="cpp-filesystem-status.html">status</a> 的调用确定(跟随符号链接至其目标)</div>
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<div class="t-li1"><span class="t-li">2)</span> 返回入口的状态,如同用 <a href="cpp-filesystem-status.html">symlink_status</a> 的调用确定(不跟随符号链接)</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>ec</td>
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<td>-</td>
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<td>不抛出重载中报告错误的输出参数</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>入口所指代的文件的状态。</p>
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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> 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=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>许多遍历目录的低层 OS API 将下个目录条目与文件属性一同获取。若它们存在,则 <code>directory_iterator</code> 的构造函数和非 const 函数将这些属性存储于所指向的 <a href="cpp-filesystem-directory_entry.html"><tt>directory_entry</tt></a> 中,而不调用 <a href="cpp-filesystem-directory_entry-refresh.html"><tt>directory_entry::refresh</tt></a> 。这使得程序能够在迭代目录条目的同时检验其属性,而不进行额外的系统调用。</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 <iostream></span>
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<span class="co2">#include <fstream></span>
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<span class="co2">#include <cstdio></span>
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<span class="co2">#include <cstring></span>
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<span class="co2">#include <filesystem></span>
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<span class="co2">#include <unistd.h></span>
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<span class="co2">#include <sys/socket.h></span>
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<span class="co2">#include <sys/un.h></span>
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<span class="co2">#include <sys/stat.h></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">void</span> demo_status<span class="br0">(</span><span class="kw4">const</span> fs<span class="sy4">::</span><span class="me2">path</span><span class="sy3">&</span> p, fs<span class="sy4">::</span><span class="me2">file_status</span> s<span class="br0">)</span>
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<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> p<span class="sy4">;</span>
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<span class="co1">// 变体: switch(s.type()) { case fs::file_type::regular: ...}</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_regular_file</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a regular file<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_directory</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a directory<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_block_file</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a block device<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_character_file</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a character device<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_fifo</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a named IPC pipe<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_socket</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a named IPC socket<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">is_symlink</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" is a symlink<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><span class="sy3">!</span>fs<span class="sy4">::</span><span class="me2">exists</span><span class="br0">(</span>s<span class="br0">)</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> <span class="st0">" does not exist<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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<span class="co1">// 创建不同种类的文件</span>
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fs<span class="sy4">::</span><span class="me2">create_directory</span><span class="br0">(</span><span class="st0">"sandbox"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-basic_ofstream.html"><span class="kw1733">std::<span class="me2">ofstream</span></span></a><span class="br0">(</span><span class="st0">"sandbox/file"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 创建常规文件</span>
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fs<span class="sy4">::</span><span class="me2">create_directory</span><span class="br0">(</span><span class="st0">"sandbox/dir"</span><span class="br0">)</span><span class="sy4">;</span>
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mkfifo<span class="br0">(</span><span class="st0">"sandbox/pipe"</span>, <span class="nu8">0644</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">struct</span> sockaddr_un addr<span class="sy4">;</span>
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addr.<span class="me1">sun_family</span> <span class="sy1">=</span> AF_UNIX<span class="sy4">;</span>
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<a href="cpp-string-byte-strcpy.html"><span class="kw1140">std::<span class="me2">strcpy</span></span></a><span class="br0">(</span>addr.<span class="me1">sun_path</span>, <span class="st0">"sandbox/sock"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">int</span> fd <span class="sy1">=</span> socket<span class="br0">(</span>PF_UNIX, SOCK_STREAM, <span class="nu0">0</span><span class="br0">)</span><span class="sy4">;</span>
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bind<span class="br0">(</span>fd, <span class="br0">(</span><span class="kw1">struct</span> sockaddr<span class="sy2">*</span><span class="br0">)</span><span class="sy3">&</span>addr, sizeof addr<span class="br0">)</span><span class="sy4">;</span>
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fs<span class="sy4">::</span><span class="me2">create_symlink</span><span class="br0">(</span><span class="st0">"file"</span>, <span class="st0">"sandbox/symlink"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 演示不同的状态访问器</span>
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<span class="kw1">for</span><span class="br0">(</span><span class="kw4">auto</span> it <span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">directory_iterator</span><span class="br0">(</span><span class="st0">"sandbox"</span><span class="br0">)</span><span class="sy4">;</span> it <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">directory_iterator</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="sy2">++</span>it<span class="br0">)</span>
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demo_status<span class="br0">(</span><span class="sy2">*</span>it, it<span class="sy2">-</span><span class="sy1">></span>symlink_status<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 从 directory_entry 使用缓冲的状态</span>
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demo_status<span class="br0">(</span><span class="st0">"dev/null"</span>, fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"/dev/null"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 直接调用 status</span>
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demo_status<span class="br0">(</span><span class="st0">"dev/sda"</span>, fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"/dev/sda"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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demo_status<span class="br0">(</span><span class="st0">"sandbox/no"</span>, fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"/sandbox/no"</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 清理</span>
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close<span class="br0">(</span>fd<span class="br0">)</span><span class="sy4">;</span>
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fs<span class="sy4">::</span><span class="me2">remove_all</span><span class="br0">(</span><span class="st0">"sandbox"</span><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>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">"sandbox/file" is a regular file
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"sandbox/dir" is a directory
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"sandbox/pipe" is a named IPC pipe
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"sandbox/sock" is a named IPC socket
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"sandbox/symlink" is a symlink
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"dev/null" is a character device
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"dev/sda" is a block device
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"sandbox/no" does not exist</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-filesystem-directory_entry-refresh.html"><span class="t-lines"><span>refresh</span></span></a></div>
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</div>
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</td>
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<td>更新缓存的文件属性<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">
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<div><a href="cpp-filesystem-directory_entry-exists.html"><span class="t-lines"><span>exists</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表既存文件系统对象<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">
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<div><a href="cpp-filesystem-directory_entry-is_block_file.html"><span class="t-lines"><span>is_block_file</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表阻塞设备<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">
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<div><a href="cpp-filesystem-directory_entry-is_character_file.html"><span class="t-lines"><span>is_character_file</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表字符设备<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">
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<div><a href="cpp-filesystem-directory_entry-is_directory.html"><span class="t-lines"><span>is_directory</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表目录<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">
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<div><a href="cpp-filesystem-directory_entry-is_fifo.html"><span class="t-lines"><span>is_fifo</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表具名管道<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">
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<div><a href="cpp-filesystem-directory_entry-is_other.html"><span class="t-lines"><span>is_other</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表<i>其他</i>文件<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">
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<div><a href="cpp-filesystem-directory_entry-is_regular_file.html"><span class="t-lines"><span>is_regular_file</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表常规文件<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">
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<div><a href="cpp-filesystem-directory_entry-is_socket.html"><span class="t-lines"><span>is_socket</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表具名 IPC 接头<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">
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<div><a href="cpp-filesystem-directory_entry-is_symlink.html"><span class="t-lines"><span>is_symlink</span></span></a></div>
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</div>
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</td>
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<td>检查 directory_entry 是否代表符号链接<br />
|
|
<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">
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<div><a href="cpp-filesystem-directory_entry-file_size.html"><span class="t-lines"><span>file_size</span></span></a></div>
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</div>
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</td>
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<td>返回 directory_entry 所指代的文件大小<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">
|
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<div><a href="cpp-filesystem-directory_entry-hard_link_count.html"><span class="t-lines"><span>hard_link_count</span></span></a></div>
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</div>
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</td>
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<td>返回引用到该 directory_entry 所表示的文件的硬链接数<br />
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<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
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<div><a href="cpp-filesystem-directory_entry-last_write_time.html"><span class="t-lines"><span>last_write_time</span></span></a></div>
|
|
</div>
|
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</td>
|
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<td>获取或设置 directory_entry 所代表的文件的最后数据修改时间<br />
|
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
|
|
</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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