75 lines
5.2 KiB
HTML
75 lines
5.2 KiB
HTML
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<title>std::basic_streambuf<CharT,Traits>::in_avail</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_streambuf<CharT,Traits>::</span>in_avail</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_streambuf.html">basic streambuf</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-io-streamsize.html"><span class="kw1804">std::<span class="me2">streamsize</span></span></a> in_avail<span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>返回获取区中可用的字符数。若读位置可用，则等效地返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">egptr<span class="br0">(</span><span class="br0">)</span> <span class="sy2">-</span> gptr<span class="br0">(</span><span class="br0">)</span></span></span> ，获取区的大小。此情况下，返回能从缓冲区释出而不调用 <span class="t-lc"><a href="cpp-io-basic_streambuf-underflow.html">underflow()</a></span> 的字节数。</p>
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<p>若获取区为空，则调用 <span class="t-lc"><a href="cpp-io-basic_streambuf-showmanyc.html">showmanyc()</a></span> 确定关联字符序列中可用的字节数。此情况下，返回值是能从缓冲区释出，同时保证 <span class="t-lc"><a href="cpp-io-basic_streambuf-underflow.html">underflow()</a></span> 不会返回 <code>Traits::eof</code> 的字节数。</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>非阻塞读取的可用字符数（从关联字符序列读取的获取区大小），或若只要 <span class="t-lc"><a href="cpp-io-basic_streambuf-showmanyc.html">showmanyc()</a></span> 能告知关联序列中无可用字符则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">-</span><span class="nu0">1</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_filebuf-showmanyc.html"><span class="t-lines"><span>showmanyc</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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<td>可选地提供可用于从文件输入的字符数<br />
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<span class="t-mark">(<code>std::basic_filebuf<CharT,Traits></code> 的虚受保护成员函数)</span></td>
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<div><a href="cpp-io-basic_istream-readsome.html"><span class="t-lines"><span>readsome</span></span></a></div>
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<td>读并取走已经可用的字符块<br />
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<span class="t-mark">(<code>std::basic_istream<CharT,Traits></code> 的公开成员函数)</span></td>
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