147 lines
10 KiB
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147 lines
10 KiB
HTML
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<title>std::basic_ispanstream<CharT,Traits>::basic_ispanstream</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_basic_ispanstream_basic_ispanstream skin-cppreference2 action-view cpp-page-template cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_ispanstream<CharT,Traits>::</span>basic_ispanstream</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_ispanstream.html">basic ispanstream</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> basic_ispanstream<span class="br0">(</span> std<span class="sy4">::</span><span class="me2">span</span><span class="sy1"><</span>CharT<span class="sy1">></span> s, <a href="cpp-io-ios_base-openmode.html"><span class="kw1671">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">openmode</span></span></a> mode <span class="sy1">=</span><br />
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<a href="cpp-io-ios_base-openmode.html"><span class="kw1674">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">in</span></span></a> <span class="br0">)</span><span class="sy4">;</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-cxx23">(C++23 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> ROS <span class="sy1">></span><br />
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<span class="kw1">explicit</span> basic_ispanstream<span class="br0">(</span> ROS<span class="sy3">&&</span> r <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-cxx23">(C++23 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp">basic_ispanstream<span class="br0">(</span> basic_ispanstream<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-cxx23">(C++23 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp">basic_ispanstream<span class="br0">(</span> <span class="kw4">const</span> basic_ispanstream<span class="sy3">&</span> <span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></div>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx23">(C++23 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>构造新的 <code>basic_ispanstream</code> 。</p>
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<div class="t-li1"><span class="t-li">1)</span> 以 <code>s</code> 所引用的存储为包装的 <span class="t-lc">std::basic_spanbuf</span> 设备的初始底层缓冲区。以 <span class="t-c"><span class="mw-geshi cpp source-cpp">basic_spanbuf<span class="sy1"><</span>Char, Traits<span class="sy1">></span><span class="br0">(</span>s, mode <span class="sy3">|</span> <a href="cpp-io-ios_base-openmode.html"><span class="kw1674">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">in</span></span></a><span class="br0">)</span></span></span> 构造包装的 <span class="t-lc">std::basic_spanbuf</span> 对象。</div>
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<div class="t-li1"><span class="t-li">2)</span> 以 <code>r</code> 转换到 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">span</span><span class="sy1"><</span><span class="kw4">const</span> CharT<span class="sy1">></span></span></span> 后所引用的存储为包装的 <span class="t-lc">std::basic_spanbuf</span> 设备的初始底层缓冲区。以模式 <span class="t-lc"><a href="cpp-io-ios_base-openmode.html">std::ios_base::in</a></span> 打开包装的 <span class="t-lc">std::basic_spanbuf</span> 对象。此重载仅若 <code>ROS</code> 实现 <a href="cpp-ranges-borrowed_range.html"><code>borrowed_range</code></a> ， <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">convertible_to</span><span class="sy1"><</span>ROS, std<span class="sy4">::</span><span class="me2">span</span><span class="sy1"><</span>CharT<span class="sy1">>></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 且 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">convertible_to</span><span class="sy1"><</span>ROS, std<span class="sy4">::</span><span class="me2">span</span><span class="sy1"><</span><span class="kw4">const</span> CharT<span class="sy1">>></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span>才参与重载决议 。</div>
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<div class="t-li1"><span class="t-li">3)</span> 移动构造函数。从 <code>rhs</code> 的 <span class="t-lc"><a href="cpp-io-basic_istream.html">std::basic_istream</a></span> 基类子对象和包装的 <span class="t-lc">std::basic_spanbuf</span> 移动构造对应的子对象，然后以 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 中包装的 <span class="t-lc">std::basic_spanbuf</span> 的地址调用 <span class="t-lc"><a href="cpp-io-basic_ios-set_rdbuf.html">set_rdbuf</a></span> 以安装它。</div>
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<div class="t-li1"><span class="t-li">4)</span> 复制构造函数被删除。 <code>basic_ispanstream</code> 不可复制。</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>s</td>
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<td>-</td>
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<td>引用要作为流的初始底层缓冲区的存储的 <span class="t-lc">std::span</span></td>
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</tr>
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<tr class="t-par">
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<td>r</td>
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<td>-</td>
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<td>要用作流的初始底层缓冲区的 <a href="cpp-ranges-borrowed_range.html"><code>borrowed_range</code></a></td>
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</tr>
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<tr class="t-par">
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<td>mode</td>
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<td>-</td>
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<td>指定打开模式。可以用下列常量或它们之间的逐位或：
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<table class="t-dsc-begin">
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<td>常量</td>
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<td>解释</td>
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<tr class="t-dsc">
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<td><a href="cpp-io-ios_base-openmode.html"><tt>app</tt></a></td>
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<td>每次写入前寻位到流结尾</td>
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</tr>
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<td><a href="cpp-io-ios_base-openmode.html"><tt>binary</tt></a></td>
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<td>以<a href="cpp-io-c-FILE.html#.E4.BA.8C.E8.BF.9B.E5.88.B6.E4.B8.8E.E6.96.87.E6.9C.AC.E6.A8.A1.E5.BC.8F">二进制模式</a>打开</td>
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<tr class="t-dsc">
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<td><a href="cpp-io-ios_base-openmode.html"><tt>in</tt></a></td>
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<td>为读打开</td>
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</tr>
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<tr class="t-dsc">
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<td><a href="cpp-io-ios_base-openmode.html"><tt>out</tt></a></td>
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<td>为写打开</td>
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</tr>
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<tr class="t-dsc">
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<td><a href="cpp-io-ios_base-openmode.html"><tt>trunc</tt></a></td>
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<td>在打开时舍弃流的内容</td>
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</tr>
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<tr class="t-dsc">
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<td><a href="cpp-io-ios_base-openmode.html"><tt>ate</tt></a></td>
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<td>打开后立即寻位到流结尾</td>
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</tr>
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</table>
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</td>
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</tr>
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<tr class="t-par">
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<td>other</td>
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<td>-</td>
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<td>要移动的另一 <code>basic_ispanstream</code></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>可能抛出实现定义的异常。</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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<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
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<td class="mbox-empty-cell"></td>
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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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</tr>
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</table>
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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-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-io-basic_spanbuf-basic_spanbuf.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx23">(C++23)</span></span></span></div>
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</div>
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</td>
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<td>构造 <code>basic_spanbuf</code> 对象<br />
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<span class="t-mark">(<code>std::basic_spanbuf<CharT,Traits></code> 的公开成员函数)</span></td>
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<div class="visualClear"></div>
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</div>
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