103 lines
7.0 KiB
HTML
103 lines
7.0 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>std::iostream_category</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_iostream_category skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>iostream_category</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-io.html">io</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<td>
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<div>定义于头文件 <code><a href="cpp-header-ios.html"><ios></a></code></div>
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</td>
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<td></td>
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<td></td>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <a href="cpp-error-error_category.html"><span class="kw871">std::<span class="me2">error_category</span></span></a><span class="sy3">&</span> iostream_category<span class="br0">(</span><span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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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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<p>获得到为 iostream 错误而设的静态 error_category 对象的引用。要求对象覆写虚函数 <span class="t-c"><span class="mw-geshi cpp source-cpp">error_category<span class="sy4">::</span><span class="me2">name</span><span class="br0">(</span><span class="br0">)</span></span></span> 以返回指向字符串 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">"iostream"</span></span></span> 的指针。它亦用于鉴别提供于 <span class="t-lc"><a href="cpp-io-ios_base-failure.html">std::ios_base::failure</a></span> 类型异常的 error_code 。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<p>（无）</p>
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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>获得到导出自 <span class="t-lc"><a href="cpp-error-error_category.html">std::error_category</a></span> 的未指定运行时类型的静态对象的引用。</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-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="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-io-basic_ifstream.html"><span class="kw1732">std::<span class="me2">ifstream</span></span></a> f<span class="br0">(</span><span class="st0">"doesn't exist"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">try</span> <span class="br0">{</span>
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f.<span class="me1">exceptions</span><span class="br0">(</span>f.<span class="me1">failbit</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span> <span class="kw1">catch</span> <span class="br0">(</span><span class="kw4">const</span> <a href="cpp-io-ios_base-failure.html"><span class="kw1670">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">failure</span></span></a><span class="sy3">&</span> e<span class="br0">)</span> <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> <span class="st0">"Caught an ios_base::failure.<span class="es1">\n</span>"</span>
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<span class="sy1"><<</span> <span class="st0">"Error code: "</span> <span class="sy1"><<</span> e.<span class="me1">code</span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">value</span><span class="br0">(</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="st0">" ("</span> <span class="sy1"><<</span> e.<span class="me1">code</span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">message</span><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">")<span class="es1">\n</span>"</span>
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<span class="sy1"><<</span> <span class="st0">"Error category: "</span> <span class="sy1"><<</span> e.<span class="me1">code</span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">category</span><span class="br0">(</span><span class="br0">)</span>.<span class="me1">name</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>
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<span class="br0">}</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">Caught an ios_base::failure.
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Error code: 1 (unspecified iostream_category error)
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Error category: iostream</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_2">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-io-ios_base-failure.html"><span class="t-lines"><span>failure</span></span></a></div>
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</div>
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</td>
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<td>流异常<br />
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<span class="t-mark">(<code>std::ios_base</code> 的公开成员类)</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-io-io_errc.html"><span class="t-lines"><span>io_errc</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>IO 流的错误码<br />
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<span class="t-mark">(枚举)</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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</div>
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</body>
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</html>
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