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<title>std::basic_streambuf&lt;CharT,Traits&gt;::setg</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_streambuf&lt;CharT,Traits&gt;::</span>setg</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-io.html">io</a>&lrm; | <a href="cpp-io-basic_streambuf.html">basic streambuf</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> setg<span class="br0">(</span> char_type<span class="sy2">*</span> gbeg, char_type<span class="sy2">*</span> gcurr, char_type<span class="sy2">*</span> gend <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>&#35774;&#32622;&#23450;&#20041;&#33719;&#21462;&#21306;&#30340;&#25351;&#38024;&#20540;&#12290;&#29305;&#21035;&#26159;&#35843;&#29992;&#21518; <span class="t-c"><span class="mw-geshi cpp source-cpp">eback<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> gbeg</span></span> &#65292; <span class="t-c"><span class="mw-geshi cpp source-cpp">gptr<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> gcurr</span></span> &#65292; <span class="t-c"><span class="mw-geshi cpp source-cpp">egptr<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> gend</span></span> &#12290;</p>
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<td>gbeg</td>
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<td>&#25351;&#21521;&#33719;&#21462;&#21306;&#26032;&#36215;&#22987;&#30340;&#25351;&#38024;</td>
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<td>gcurr</td>
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<td>&#25351;&#21521;&#33719;&#21462;&#21306;&#20013;&#26032;&#30340;&#24403;&#21069;&#23383;&#31526;&#30340;&#25351;&#38024;&#65288;<i>&#33719;&#21462;&#25351;&#38024;</i>&#65289;</td>
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<td>gend</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#65288;&#26080;&#65289;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;sstream&gt;</span>
<span class="kw1">class</span> null_filter_buf <span class="sy4">:</span> <span class="kw1">public</span> <a href="cpp-io-basic_streambuf.html"><span class="kw1724">std::<span class="me2">streambuf</span></span></a> <span class="br0">{</span>
<a href="cpp-io-basic_streambuf.html"><span class="kw1724">std::<span class="me2">streambuf</span></span></a><span class="sy2">*</span> src<span class="sy4">;</span>
<span class="kw4">char</span> ch<span class="sy4">;</span> <span class="co1">// &#21333;&#23383;&#33410;&#32531;&#20914;&#21306;</span>
<span class="kw1">protected</span><span class="sy4">:</span>
<span class="kw4">int</span> underflow<span class="br0">(</span><span class="br0">)</span> <span class="br0">{</span>
traits_type<span class="sy4">::</span><span class="me2">int_type</span> i<span class="sy4">;</span>
<span class="kw1">while</span> <span class="br0">(</span><span class="br0">(</span>i <span class="sy1">=</span> src<span class="sy2">-</span><span class="sy1">&gt;</span>sbumpc<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="st0">&#39;<span class="es5">\0</span>&#39;</span><span class="br0">)</span> <span class="sy4">;</span> <span class="co1">// &#36339;&#36807;&#38646;</span>
<span class="kw1">if</span> <span class="br0">(</span>traits_type<span class="sy4">::</span><span class="me2">not_eof</span><span class="br0">(</span>i<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
ch <span class="sy1">=</span> traits_type<span class="sy4">::</span><span class="me2">to_char_type</span><span class="br0">(</span>i<span class="br0">)</span><span class="sy4">;</span>
setg<span class="br0">(</span><span class="sy3">&amp;</span>ch, <span class="sy3">&amp;</span>ch, <span class="sy3">&amp;</span>ch<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// &#20351;&#24471;&#19968;&#20010;&#35835;&#21462;&#20301;&#32622;&#21487;&#29992;</span>
<span class="br0">}</span>
<span class="kw1">return</span> i<span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw1">public</span><span class="sy4">:</span>
null_filter_buf<span class="br0">(</span><a href="cpp-io-basic_streambuf.html"><span class="kw1724">std::<span class="me2">streambuf</span></span></a><span class="sy2">*</span> buf<span class="br0">)</span> <span class="sy4">:</span> src<span class="br0">(</span>buf<span class="br0">)</span> <span class="br0">{</span>
setg<span class="br0">(</span><span class="sy3">&amp;</span>ch, <span class="sy3">&amp;</span>ch<span class="sy2">+</span><span class="nu0">1</span>, <span class="sy3">&amp;</span>ch<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// &#32531;&#20914;&#21306;&#21021;&#22987;&#20026;&#28385;</span>
<span class="br0">}</span>
<span class="br0">}</span><span class="sy4">;</span>
<span class="kw4">void</span> filtered_read<span class="br0">(</span><a href="cpp-io-basic_istream.html"><span class="kw1727">std::<span class="me2">istream</span></span></a><span class="sy3">&amp;</span> in<span class="br0">)</span>
<span class="br0">{</span>
<a href="cpp-io-basic_streambuf.html"><span class="kw1724">std::<span class="me2">streambuf</span></span></a><span class="sy2">*</span> orig <span class="sy1">=</span> in.<span class="me1">rdbuf</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
null_filter_buf buf<span class="br0">(</span>orig<span class="br0">)</span><span class="sy4">;</span>
in.<span class="me1">rdbuf</span><span class="br0">(</span><span class="sy3">&amp;</span>buf<span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">for</span><span class="br0">(</span><span class="kw4">char</span> c<span class="sy4">;</span> in.<span class="me1">get</span><span class="br0">(</span>c<span class="br0">)</span><span class="sy4">;</span> <span class="br0">)</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> c<span class="sy4">;</span>
in.<span class="me1">rdbuf</span><span class="br0">(</span>orig<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">char</span> a<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">&quot;This i<span class="es5">\0</span>s <span class="es5">\0</span>an e<span class="es5">\0</span><span class="es5">\0</span><span class="es5">\0</span>xample&quot;</span><span class="sy4">;</span>
<a href="cpp-io-basic_istringstream.html"><span class="kw1735">std::<span class="me2">istringstream</span></span></a> in<span class="br0">(</span><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="br0">(</span><a href="cpp-iterator-begin.html"><span class="kw676">std::<span class="me2">begin</span></span></a><span class="br0">(</span>a<span class="br0">)</span>, <a href="cpp-iterator-end.html"><span class="kw680">std::<span class="me2">end</span></span></a><span class="br0">(</span>a<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
filtered_read<span class="br0">(</span>in<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<pre class="de1">This is an example</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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<div><a href="cpp-io-basic_streambuf-setp.html"><span class="t-lines"><span>setp</span></span></a></div>
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<td>&#37325;&#23450;&#20301;&#36755;&#20986;&#24207;&#21015;&#30340;&#36215;&#22987;&#12289;&#19979;&#19968;&#20301;&#32622;&#21644;&#32456;&#27490;&#25351;&#38024;<br />
<span class="t-mark">(&#21463;&#20445;&#25252;&#25104;&#21592;&#20989;&#25968;)</span></td>
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