218 lines
19 KiB
HTML
218 lines
19 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::copy_file</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_copy_file 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>copy_file</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="kw4">bool</span> copy_file<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> from,<br /></span>
|
|
<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> to <span class="br0">)</span><span class="sy4">;</span><br />
|
|
<span class="kw4">bool</span> copy_file<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> from,<br />
|
|
<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> to,<br /></p>
|
|
<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>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx17">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span> copy_file<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> from,<br /></span>
|
|
<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> to,<br />
|
|
<a href="cpp-filesystem-copy_options.html"><span class="kw2242">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">copy_options</span></span></a> options <span class="br0">)</span><span class="sy4">;</span><br />
|
|
<span class="kw4">bool</span> copy_file<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> from,<br />
|
|
<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> to,<br />
|
|
<a href="cpp-filesystem-copy_options.html"><span class="kw2242">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">copy_options</span></span></a> options,<br /></p>
|
|
<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>
|
|
</td>
|
|
<td>(2)</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>
|
|
<div class="t-li1"><span class="t-li">1)</span> 默认,等价于以 <code>copy_options::none</code> 为 <code>options</code> 的 <span class="t-v">(2)</span></div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 从 <code>from</code> 到 <code>to</code> 复制单个文件,使用 <code>options</code> 所指示的复制选项。若 <code>options</code> 中存在任一 <a href="cpp-filesystem-copy_options.html">copy_options</a> 选项组中多于一个的选项,则行为未定义(即使在无关乎 <code>copy_file</code> 的组中)。
|
|
<ul>
|
|
<li>若 <a href="cpp-filesystem-is_regular_file.html"><tt>!is_regular_file(from)</tt></a> (因为源文件不存在或它不是常规文件),则报告错误</li>
|
|
<li>否则,若目标文件不存在,则</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>复制 <code>from</code> 所解析到的文件的内容及属性到 <code>to</code> 所解析到者(跟随符号链接)</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<ul>
|
|
<li>否则,若目标文件已存在……</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li>若下列之一为真则报告错误:</li>
|
|
</ul>
|
|
<dl>
|
|
<dd>
|
|
<ul>
|
|
<li><code>to</code> 与 <code>from</code> 相同,以 <a href="cpp-filesystem-equivalent.html"><tt>equivalent(from, to)</tt></a> 确定;</li>
|
|
<li><code>to</code> 不是常规文件,以 <a href="cpp-filesystem-is_regular_file.html"><tt>!is_regular_file(to)</tt></a> 确定</li>
|
|
<li><code>options</code> 中未设置任何 <code>copy_file</code> 控制选项</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
<ul>
|
|
<li>否则,若 <code>copy_options::skip_existing</code> 设置于 <code>options</code> ,则不做任何事</li>
|
|
<li>否则,若 <code>copy_options::overwrite_existing</code> 设置于 <code>options</code> ,则复制 <code>from</code> 所解析到的文件的内容及属性到 <code>to</code> 所解析到的文件</li>
|
|
<li>否则,若 <code>copy_options::update_existing</code> 设置于 <code>options</code> ,则仅若 <code>from</code> 按 <a href="cpp-filesystem-last_write_time.html"><tt>last_write_time()</tt></a> 定义新于 <code>to</code> 才复制</li>
|
|
</ul>
|
|
</dd>
|
|
</dl>
|
|
</div>
|
|
<p>若错误发生,则不抛出重载返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 。</p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>from</td>
|
|
<td>-</td>
|
|
<td>源文件的路径</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>to</td>
|
|
<td>-</td>
|
|
<td>目标文件的路径</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>ec</td>
|
|
<td>-</td>
|
|
<td>不抛出重载中报告错误的输出参数</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>若文件被复制则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ,否则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 。</p>
|
|
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
|
|
<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>from</code>,第二 path 参数 <code>to</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>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
|
|
<p>函数最多引入一次对 <a href="cpp-filesystem-status.html"><tt>status(to)</tt></a> 的直接或间接调用(均用于确定文件是否存在,及对于 <code>copy_options::update_existing</code> 选项,确定其最后写入时间)</p>
|
|
<p>当 <code>copy_file</code> 被用于复制目录时报告错误:用 <a href="cpp-filesystem-copy.html"><tt>copy</tt></a> 复制它们。</p>
|
|
<p><code>copy_file</code> 跟随符号链接:用 <a href="cpp-filesystem-copy_symlink.html"><tt>copy_symlink</tt></a> 或 <a href="cpp-filesystem-copy.html"><tt>copy</tt></a> 带 <code>copy_options::copy_symlinks</code> 复制它们。</p>
|
|
<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/issue3014">LWG 3014</a></td>
|
|
<td>C++17</td>
|
|
<td><code>error_code</code> 重载被标记为 noexcept 但能分配内存</td>
|
|
<td>移除 noexcept</td>
|
|
</tr>
|
|
</table>
|
|
<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_directory</span><span class="br0">(</span><span class="st0">"sandbox"</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="me1">put</span><span class="br0">(</span><span class="st0">'a'</span><span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
fs<span class="sy4">::</span><span class="me2">copy_file</span><span class="br0">(</span><span class="st0">"sandbox/file1.txt"</span>, <span class="st0">"sandbox/file2.txt"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<span class="co1">// 现在 sandbox 中有二个文件:</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">"file1.txt holds : "</span>
|
|
<span class="sy1"><<</span> <a href="cpp-io-basic_ifstream.html"><span class="kw1732">std::<span class="me2">ifstream</span></span></a><span class="br0">(</span><span class="st0">"sandbox/file1.txt"</span><span class="br0">)</span>.<span class="me1">rdbuf</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>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"file2.txt holds : "</span>
|
|
<span class="sy1"><<</span> <a href="cpp-io-basic_ifstream.html"><span class="kw1732">std::<span class="me2">ifstream</span></span></a><span class="br0">(</span><span class="st0">"sandbox/file2.txt"</span><span class="br0">)</span>.<span class="me1">rdbuf</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>
|
|
|
|
<span class="co1">// 复制目录失败</span>
|
|
fs<span class="sy4">::</span><span class="me2">create_directory</span><span class="br0">(</span><span class="st0">"sandbox/abc"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw1">try</span> <span class="br0">{</span>
|
|
fs<span class="sy4">::</span><span class="me2">copy_file</span><span class="br0">(</span><span class="st0">"sandbox/abc"</span>, <span class="st0">"sandbox/def"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span> <span class="kw1">catch</span><span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">filesystem_error</span><span class="sy3">&</span> e<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">"Could not copy sandbox/abc: "</span> <span class="sy1"><<</span> e.<span class="me1">what</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>
|
|
<span class="br0">}</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">file1.txt holds : a
|
|
file2.txt holds : a
|
|
Could not copy sandbox/abc: copy_file: Is a directory: "sandbox/abc", "sandbox/def"</pre></div>
|
|
</div>
|
|
</div>
|
|
<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-copy_options.html"><span class="t-lines"><span>copy_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>指定复制操作的语义<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-copy_symlink.html"><span class="t-lines"><span>copy_symlink</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>复制一个符号链接<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-copy.html"><span class="t-lines"><span>copy</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>复制文件或目录<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|