102 lines
6.8 KiB
HTML
102 lines
6.8 KiB
HTML
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<title>std::basic_ostream<CharT,Traits>::basic_ostream</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_ostream<CharT,Traits>::</span>basic_ostream</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_ostream.html">basic ostream</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> basic_ostream<span class="br0">(</span> <a href="cpp-io-basic_streambuf.html"><span class="kw1666">std::<span class="me2">basic_streambuf</span></span></a><span class="sy1"><</span>CharT, Traits<span class="sy1">></span><span class="sy2">*</span> sb <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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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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basic_ostream<span class="br0">(</span> <span class="kw4">const</span> basic_ostream<span class="sy3">&</span> rhs <span class="br0">)</span> <span class="sy1">=</span> delete<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">protected</span><span class="sy4">:</span><br />
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basic_ostream<span class="br0">(</span> basic_ostream<span class="sy3">&&</span> rhs <span class="br0">)</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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<p>1) 构造 <code>basic_ostream</code> 对象，通过调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">basic_ios<span class="sy4">::</span><span class="me2">init</span><span class="br0">(</span>sb<span class="br0">)</span></span></span> 赋初值给基类。</p>
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<p>2) 复制构造函数被删除。输出流不可复制。</p>
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<p>3) 移动构造函数用 <code>basic_ios<CharT, Traits>::move(rhs)</code> 从 <code>rhs</code> 移动所有 basic_ios ，除了 <code>rdbuf()</code> 到 <code>*this</code> 中。此移动构造函数受保护：它为可移动输出流类 <span class="t-lc"><a href="cpp-io-basic_ofstream.html">std::basic_ofstream</a></span> 和 <span class="t-lc"><a href="cpp-io-basic_ostringstream.html">std::basic_ostringstream</a></span> 的移动构造函数所调用，它们知道如何正确地移动关联的流缓冲。</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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<td>sb</td>
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<td>-</td>
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<td>用作输出序列的流缓冲</td>
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<tr class="t-par">
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<td>rhs</td>
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<td>-</td>
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<td>初始化来源的 basic_ostream</td>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <sstream></span>
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<span class="co2">#include <utility></span>
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<span class="co2">#include <iostream></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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<span class="co1">// 错误：复制构造函数被删除</span>
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<span class="co1">// std::ostream myout(std::cout);</span>
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<span class="co1">// OK ：与 cout 共享缓冲</span>
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<a href="cpp-io-basic_ostream.html"><span class="kw1729">std::<span class="me2">ostream</span></span></a> myout<span class="br0">(</span><a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>.<span class="me1">rdbuf</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 错误：移动构造函数受保护</span>
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<span class="co1">// std::ostream s2(std::move(std::ostringstream() << 7.1)); </span>
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<span class="co1">// OK ：通过导出类调用移动构造函数</span>
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<a href="cpp-io-basic_ostringstream.html"><span class="kw1736">std::<span class="me2">ostringstream</span></span></a> s2<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span><a href="cpp-io-basic_ostringstream.html"><span class="kw1736">std::<span class="me2">ostringstream</span></span></a><span class="br0">(</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="nu16">7.1</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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myout <span class="sy1"><<</span> s2.<span class="me1">str</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></pre></div>
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<p>输出：</p>
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<div class="text source-text">
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<pre class="de1">7.1</pre></div>
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