111 lines
7.0 KiB
HTML
111 lines
7.0 KiB
HTML
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<title>std::error_code::error_code</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_error_error_code_error_code 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::error_code::</span>error_code</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-error.html">error</a>‎ | <a href="cpp-error-error_code.html">error code</a></span></div>
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<div><span class="mw-geshi cpp source-cpp">error_code<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp">error_code<span class="br0">(</span> <span class="kw4">int</span> ec, <span class="kw4">const</span> error_category<span class="sy3">&</span> ecat <span class="br0">)</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-cxx11">(C++11 起)</span></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> ErrorCodeEnum <span class="sy1">></span><br />
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error_code<span class="br0">(</span> ErrorCodeEnum e <span class="br0">)</span> <span class="kw1">noexcept</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-cxx11">(C++11 起)</span></td>
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<td></td>
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<td></td>
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<p>构造新的 error_code 。</p>
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<div class="t-li1"><span class="t-li">1)</span> 构造带默认值的 error_code 。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">error_code<span class="br0">(</span><span class="nu0">0</span>, <a href="cpp-error-system_category.html"><span class="kw873">std::<span class="me2">system_category</span></span></a><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 以 <code>ec</code> 为平台依赖的错误码并以 <code>ecat</code> 为对应的<a href="cpp-error-error_category.html">错误类别</a>构造 error_code 。</div>
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<div class="t-li1"><span class="t-li">3)</span> 从错误码枚举 <code>e</code> 构造 error_code 。等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">make_error_code<span class="br0">(</span>e<span class="br0">)</span></span></span> ，其中 <code>make_error_code</code> 由<a href="cpp-language-adl.html">实参依赖查找</a>找到。此重载仅若<span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-error-error_code-is_error_code_enum.html"><span class="kw878">std::<span class="me2">is_error_code_enum</span></span></a><span class="sy1"><</span>ErrorCodeEnum<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 才参与重载决议。</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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<td>ec</td>
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<td>-</td>
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<td>用以构造的平台依赖的错误码</td>
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<tr class="t-par">
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<td>ecat</td>
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<td>-</td>
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<td>对应 <code>ec</code> 的 error_category</td>
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<tr class="t-par">
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<td>e</td>
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<td>-</td>
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<td>用以构造的错误码枚举</td>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>最初的提案 <a rel="nofollow" class="external text" href="https://wg21.link/N2422">N2422</a> 中有意使用 ADL 所找到的 <code>make_error_code</code> ，并且已知实现均使用它。然而，标准要求只考虑 <code>std::make_error_code</code> 重载。此为 <a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3629">LWG 问题 3629</a> 。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div class="t-dsc-member-div">
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<div><a href="cpp-error-errc-make_error_code.html"><span class="t-lines"><span>make_error_code<span class="t-dsc-small">(std::errc)</span></span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>构造 <span class="t-lc"><a href="cpp-error-errc.html">std::errc</a></span> 错误码<br />
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<span class="t-mark">(函数)</span></td>
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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-io-io_errc-make_error_code.html"><span class="t-lines"><span>make_error_code<span class="t-dsc-small">(std::io_errc)</span></span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>构造一个 iostream 错误码<br />
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<span class="t-mark">(函数)</span></td>
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<tr class="t-dsc">
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<div><a href="cpp-thread-future_errc-make_error_code.html"><span class="t-lines"><span>make_error_code<span class="t-dsc-small">(std::future_errc)</span></span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>构造一个 future error_code<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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