80 lines
6.2 KiB
HTML
80 lines
6.2 KiB
HTML
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<title>std::basic_filebuf<CharT,Traits>::overflow</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_basic_filebuf_overflow 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::basic_filebuf<CharT,Traits>::</span>overflow</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-io.html">io</a>‎ | <a href="cpp-io-basic_filebuf.html">basic filebuf</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">protected</span><span class="sy4">:</span><br />
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<span class="kw1">virtual</span> int_type overflow <span class="br0">(</span> int_type c <span class="sy1">=</span> Traits<span class="sy4">::</span><span class="me2">eof</span><span class="br0">(</span><span class="br0">)</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>从放置区写一些数据到关联字符序列（到文件）。</p>
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<p>表现类似基类的 <span class="t-lc"><a href="cpp-io-basic_streambuf-overflow.html">std::basic_streambuf::overflow</a></span> ，除了要写入数据。首先用感染的 locale 的 <span class="t-lc"><a href="cpp-locale-codecvt-out.html">std::codecvt::out</a></span> 转换字符为外部（可能为多字节）表示，并存储于临时缓冲区中（分配所需大小），然后用文件 I/O 复制所有完全转换的字节到文件。</p>
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<p>若 <span class="t-lc"><a href="cpp-locale-codecvt-always_noconv.html">std::codecvt::always_noconv</a></span> 为 true ，则可以跳过对 <span class="t-lc"><a href="cpp-locale-codecvt-out.html">std::codecvt::out</a></span> 的调用。</p>
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<p>若转换因 <span class="t-lc"><a href="cpp-locale-codecvt_base.html">std::codecvt_base::error</a></span> 失败，则返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">Traits<span class="sy4">::</span><span class="me2">eof</span><span class="br0">(</span><span class="br0">)</span></span></span> 而不尝试任何输出。</p>
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<p>若未打开关联文件（ <span class="t-c"><span class="mw-geshi cpp source-cpp">is_open<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span> ），则在做任何事前返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">Traits<span class="sy4">::</span><span class="me2">eof</span><span class="br0">(</span><span class="br0">)</span></span></span> 。</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>指示成功的 <span class="t-c"><span class="mw-geshi cpp source-cpp">Traits<span class="sy4">::</span><span class="me2">not_eof</span><span class="br0">(</span>c<span class="br0">)</span></span></span> 或指示失败的 <span class="t-c"><span class="mw-geshi cpp source-cpp">Traits<span class="sy4">::</span><span class="me2">eof</span><span class="br0">(</span><span class="br0">)</span></span></span> 。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</td>
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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-io-basic_streambuf-overflow.html"><span class="t-lines"><span>overflow</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>从放置区写入字符到关联的输出序列<br />
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<span class="t-mark">(<code>std::basic_streambuf<CharT,Traits></code> 的虚受保护成员函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_filebuf-underflow.html"><span class="t-lines"><span>underflow</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-cmark">[虚]</span></span></span></div>
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</div>
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</td>
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<td>从关联文件读取<br />
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<span class="t-mark">(虚受保护成员函数)</span></td>
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