249 lines
17 KiB
HTML
249 lines
17 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::filesystem::directory_iterator</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_directory_iterator skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::</span>directory_iterator</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-filesystem.html">filesystem</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><a href="cpp-header-filesystem.html"><filesystem></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx17">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">class</span> directory_iterator<span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p><code>directory_iterator</code> 是一个迭代于目录的 <a href="cpp-filesystem-directory_entry.html"><tt>directory_entry</tt></a> 元素上的<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> (但不造访子目录)。迭代顺序是未指定的,除了每个目录条目只被造访一次。跳过特殊路径名 <span class="t-spar">dot</span> 和 <span class="t-spar">dot-dot</span> 。</p>
|
|
<p>若前移 <code>directory_iterator</code> 越过了最终目录条目,则它变为等于默认构造的迭代器,亦称为终止迭代器。二个终止迭代器始终相等,解引用或自增终止迭代器是未定义行为。</p>
|
|
<p>若在创建目录迭代器之后将文件或目录删除或添加到目录树,则是否会通过迭代器观察到更改是未指定的。</p>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc-hitem">
|
|
<td>成员类型</td>
|
|
<td>定义</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>value_type</code></td>
|
|
<td><span class="t-lc"><a href="cpp-filesystem-directory_entry.html">std::filesystem::directory_entry</a></span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>difference_type</code></td>
|
|
<td><span class="t-lc"><a href="cpp-types-ptrdiff_t.html">std::ptrdiff_t</a></span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>pointer</code></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <a href="cpp-filesystem-directory_entry.html"><span class="kw2203">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">directory_entry</span></span></a><span class="sy2">*</span></span></span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>reference</code></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <a href="cpp-filesystem-directory_entry.html"><span class="kw2203">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">directory_entry</span></span></a><span class="sy3">&</span></span></span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>iterator_category</code></td>
|
|
<td><span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::input_iterator_tag</a></span></td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div t-dsc-member-nobold-div">
|
|
<div><a href="cpp-filesystem-directory_iterator-directory_iterator.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>构造 directory_iterator<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div t-dsc-member-nobold-div">
|
|
<div><span class="t-lines"><span>(析构函数)</span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>默认析构函数<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-directory_iterator-operator=.html"><span class="t-lines"><span>operator=</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>对内容赋值<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-directory_iterator-operator*.html"><span class="t-lines"><span>operator*</span><span>operator-></span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>访问所指的目录条目<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-directory_iterator-increment.html"><span class="t-lines"><span>increment</span><span>operator++</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>前进到下个目录条目<br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E9.9D.9E.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">非成员函数</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-directory_iterator-begin.html"><span class="t-lines"><span>begin<span class="t-dsc-small">(std::filesystem::directory_iterator)</span></span><span>end<span class="t-dsc-small">(std::filesystem::directory_iterator)</span></span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>基于范围的 for 循环支持<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
<p>另外按<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> 所要求提供 <span class="t-rev-inl t-until-cxx20"><span><code>operator==</code> 和 <code>operator!=</code></span> <span><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></span></span><span class="t-rev-inl t-since-cxx20"><span><code>operator==</code></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> 。</p>
|
|
<p><span class="t-rev-inl t-since-cxx20"><span>是否提供 <code>operator!=</code> (因为它能从 <code>operator==</code> 合成),以及</span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span>相等运算符是成员还是非成员是未指定的。</p>
|
|
<h3><span class="mw-headline" id=".E8.BE.85.E5.8A.A9.E6.A8.A1.E6.9D.BF">辅助模板</span></h3>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">namespace</span> std<span class="sy4">::</span><span class="me2">ranges</span> <span class="br0">{</span><br /></span>
|
|
<p><span class="kw1">template</span><span class="sy1"><></span><br />
|
|
<span class="kw1">inline</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span><br />
|
|
enable_borrowed_range<span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">directory_iterator</span><span class="sy1">></span> <span class="sy1">=</span> <span class="kw2">true</span><span class="sy4">;</span><br /></p>
|
|
<span class="br0">}</span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">namespace</span> std<span class="sy4">::</span><span class="me2">ranges</span> <span class="br0">{</span><br /></span>
|
|
<p><span class="kw1">template</span><span class="sy1"><></span><br />
|
|
<span class="kw1">inline</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> enable_view<span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">directory_iterator</span><span class="sy1">></span> <span class="sy1">=</span> <span class="kw2">true</span><span class="sy4">;</span><br /></p>
|
|
<span class="br0">}</span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>这些对 <code>directory_iterator</code> 的特化使之为 <a href="cpp-ranges-borrowed_range.html"><code>borrowed_range</code></a> 及 <a href="cpp-ranges-view.html"><code>view</code></a> 。</p>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<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>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co2">#include <fstream></span>
|
|
<span class="co2">#include <iostream></span>
|
|
<span class="co2">#include <filesystem></span>
|
|
<span class="kw1">namespace</span> fs <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">;</span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
fs<span class="sy4">::</span><span class="me2">create_directories</span><span class="br0">(</span><span class="st0">"sandbox/a/b"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<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/file1.txt"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<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/file2.txt"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">auto</span><span class="sy3">&</span> p<span class="sy4">:</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="br0">)</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> p.<span class="me1">path</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
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>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>可能的输出:</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">"sandbox/a"
|
|
"sandbox/file1.txt"
|
|
"sandbox/file2.txt"</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
|
|
<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>
|
|
<table class="dsctable" style="font-size:0.8em">
|
|
<tr>
|
|
<th>DR</th>
|
|
<th>应用于</th>
|
|
<th>出版时的行为</th>
|
|
<th>正确行为</th>
|
|
</tr>
|
|
<tr>
|
|
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3480">LWG 3480</a></td>
|
|
<td>C++20</td>
|
|
<td><code>directory_iterator</code> 既非 <a href="cpp-ranges-borrowed_range.html"><code>borrowed_range</code></a> 亦非 <a href="cpp-ranges-view.html"><code>view</code></a></td>
|
|
<td>它都是</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-recursive_directory_iterator.html"><span class="t-lines"><span>recursive_directory_iterator</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>指向一个目录及其子目录的内容的迭代器<br />
|
|
<span class="t-mark">(类)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-directory_options.html"><span class="t-lines"><span>directory_options</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>用于迭代目录内容的选项<br />
|
|
<span class="t-mark">(枚举)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-directory_entry.html"><span class="t-lines"><span>directory_entry</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>目录条目<br />
|
|
<span class="t-mark">(类)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|