124 lines
7.8 KiB
HTML
124 lines
7.8 KiB
HTML
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::strstreambuf::setbuf</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_strstreambuf_setbuf skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::strstreambuf::</span>setbuf</h1>
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<div id="bodyContent">
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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-strstreambuf.html">strstreambuf</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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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> streambuf<span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span><span class="sy2">*</span> setbuf<span class="br0">(</span><span class="kw4">char</span><span class="sy2">*</span> s, <a href="cpp-io-streamsize.html"><span class="kw1804">std::<span class="me2">streamsize</span></span></a> n<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td></td>
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<td></td>
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<td></td>
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</tbody>
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</table>
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<p>若 <code>s</code> 为空指针且 <code>n</code> 为零，则函数无效果。</p>
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<p>否则，效果为实现定义：一些实现不做任何事，而一些实现解分配动态成员数组并使用用户提供的大小为 <code>n</code> ，首元素为 <code>s</code> 所指向的数组。</p>
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<p>此函数为受保护虚，它仅可通过 <code>pubsetbuf()</code> 或从导出自 <code>std::strstreambuf</code> 的用户定义类调用。</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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<table class="t-par-begin">
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<tr class="t-par">
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<td>s</td>
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<td>-</td>
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<td>指向用户提供缓冲区中首字节的指针</td>
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</tr>
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<tr class="t-par">
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<td>n</td>
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<td>-</td>
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<td>用户提供缓冲区中的字节数</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><span class="t-c"><span class="mw-geshi cpp source-cpp">this</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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<div class="t-example">
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<p>检查是否在动态 strstream 上支持 setbuf() 的实现测试（输出以 Sun Studio 获得）</p>
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <strstream></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="kw4">char</span> a<span class="br0">[</span><span class="nu0">100</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span>
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<a href="cpp-io-strstream.html"><span class="kw1755">std::<span class="me2">strstream</span></span></a> str<span class="sy4">;</span>
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str.<span class="me1">rdbuf</span><span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">></span>pubsetbuf<span class="br0">(</span>a, sizeof a<span class="br0">)</span><span class="sy4">;</span>
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str <span class="sy1"><<</span> <span class="st0">"Test string"</span> <span class="sy1"><<</span> <a href="cpp-io-manip-ends.html"><span class="kw1789">std::<span class="me2">ends</span></span></a><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"user-provided buffer holds '"</span> <span class="sy1"><<</span> a <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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</div>
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<p>可能的输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">user-provided buffer holds 'Test string'</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_streambuf-pubsetbuf.html"><span class="t-lines"><span>pubsetbuf</span></span></a></div>
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</div>
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</td>
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<td>调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">setbuf<span class="br0">(</span><span class="br0">)</span></span></span><br />
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<span class="t-mark">(<code>std::basic_streambuf<CharT,Traits></code> 的公开成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_streambuf-pubsetbuf.html"><span class="t-lines"><span>setbuf</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>若容许则以用户定义数组替换缓冲区<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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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_stringbuf-setbuf.html"><span class="t-lines"><span>setbuf</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>试图以数组替换受控字符序列<br />
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<span class="t-mark">(<code>std::basic_stringbuf<CharT,Traits,Allocator></code> 的虚受保护成员函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_filebuf-setbuf.html"><span class="t-lines"><span>setbuf</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>提供用户供应的缓冲区，或将此 filebuf 转变为无缓冲<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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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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