99 lines
5.9 KiB
HTML
99 lines
5.9 KiB
HTML
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<title>std::fegetenv, std::fesetenv</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_fenv_feenv 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::</span>fegetenv, <span style="font-size:0.7em; line-height:130%">std::</span>fesetenv</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-numeric.html">numeric</a>‎ | <a href="cpp-numeric-fenv.html">fenv</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-cfenv.html"><cfenv></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fegetenv<span class="br0">(</span> std<span class="sy4">::</span><span class="me2">fenv_t</span><span class="sy2">*</span> envp <span class="br0">)</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-cxx11">(C++11 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fesetenv<span class="br0">(</span> <span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">fenv_t</span><span class="sy2">*</span> envp <span class="br0">)</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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<td></td>
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<td></td>
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<td></td>
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<p>管理浮点环境的状态。</p>
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<div class="t-li1"><span class="t-li">1)</span> 试图存储浮点环境的状态于 <code>envp</code> 所指向的对象。</div>
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<div class="t-li1"><span class="t-li">2)</span> 试图从 <code>envp</code> 所指向的对象建立浮点环境状态。对象的值必须是以先前调用 <span class="t-lc"><a href="cpp-numeric-fenv-feholdexcept.html">std::feholdexcept</a></span> 或 <code>std::fegetenv</code> 获得值或是浮点宏常量。若 <code>envp</code> 中设置了任何浮点状态标志，则环境中标志变为被设置（然后可用 <span class="t-lc"><a href="cpp-numeric-fenv-fetestexcept.html">std::fetestexcept</a></span> 测试），但不引发对应的浮点异常（执行持续而不中断）。</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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<td>envp</td>
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<td>-</td>
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<td>指向 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">fenv_t</span></span></span> 类型对象的指针，该对象保有浮点环境的状态</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>成功时为 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> ，否则为非零。</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><a href="cpp-numeric-fenv-feholdexcept.html"><span class="t-lines"><span>feholdexcept</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>保存环境，清除所有状态标志，并忽略所有将来的错误<br />
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<span class="t-mark">(函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-fenv-feupdateenv.html"><span class="t-lines"><span>feupdateenv</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>恢复浮点环境并引发之前引发的异常<br />
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<span class="t-mark">(函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-fenv-FE_DFL_ENV.html"><span class="t-lines"><span>FE_DFL_ENV</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>默认浮点环境<br />
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<span class="t-mark">(宏常量)</span></td>
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