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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>unitbuf, <span style="font-size:0.7em; line-height:130%">std::</span>nounitbuf</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-manip.html">manip</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-ios.html">&lt;ios&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-io-ios_base.html"><span class="kw1669">std::<span class="me2">ios_base</span></span></a><span class="sy3">&amp;</span> unitbuf<span class="br0">(</span> <a href="cpp-io-ios_base.html"><span class="kw1669">std::<span class="me2">ios_base</span></span></a><span class="sy3">&amp;</span> str <span class="br0">)</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp"><a href="cpp-io-ios_base.html"><span class="kw1669">std::<span class="me2">ios_base</span></span></a><span class="sy3">&amp;</span> nounitbuf<span class="br0">(</span> <a href="cpp-io-ios_base.html"><span class="kw1669">std::<span class="me2">ios_base</span></span></a><span class="sy3">&amp;</span> str <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>&#21551;&#29992;&#25110;&#31105;&#29992;&#20219;&#20309;&#36755;&#20986;&#25805;&#20316;&#21518;&#30340;&#33258;&#21160;&#20914;&#20837;&#12290;&#22312;&#36755;&#20837;&#26102;&#26080;&#25928;&#26524;&#12290;</p>
<p>1) &#22914;&#21516;&#29992;&#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp">str.<span class="me1">setf</span><span class="br0">(</span><a href="cpp-io-ios_base-fmtflags.html"><span class="kw1695">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">unitbuf</span></span></a><span class="br0">)</span></span></span> &#21551;&#29992;&#27969; <code>str</code> &#20013;&#30340; <code>unitbuf</code> &#26631;&#24535;</p>
<p>2) &#22914;&#21516;&#29992;&#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp">str.<span class="me1">unsetf</span><span class="br0">(</span><a href="cpp-io-ios_base-fmtflags.html"><span class="kw1695">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">unitbuf</span></span></a><span class="br0">)</span></span></span> &#31105;&#29992;&#27969; <code>str</code> &#20013;&#30340; <code>unitbuf</code> &#26631;&#24535;</p>
<p>&#36825;&#26159;&#19968;&#20010; I/O &#25805;&#32437;&#31526;&#65292;&#21487;&#29992;&#22914; <span class="t-c"><span class="mw-geshi cpp source-cpp">out <span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">unitbuf</span></span></span> &#30340;&#34920;&#36798;&#24335;&#23545;&#20219;&#20309; <span class="t-lc"><a href="cpp-io-basic_ostream.html">std::basic_ostream</a></span> &#31867;&#22411;&#30340; <code>out</code> &#25110;&#29992;&#22914; <span class="t-c"><span class="mw-geshi cpp source-cpp">in <span class="sy1">&gt;&gt;</span> std<span class="sy4">::</span><span class="me2">unitbuf</span></span></span> &#30340;&#34920;&#36798;&#24335;&#23545;&#20219;&#20309; <span class="t-lc"><a href="cpp-io-basic_istream.html">std::basic_istream</a></span> &#31867;&#22411;&#30340; <code>in</code> &#35843;&#29992;&#12290;</p>
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">&#27880;&#35299;</span></h3>
<p>&#22312; <span class="t-lc"><a href="cpp-io-basic_ostream-sentry.html">std::basic_ostream::sentry</a></span> &#23545;&#35937;&#30340;&#26512;&#26500;&#20989;&#25968;&#20013;&#36827;&#34892;&#20914;&#20837;&#65292;&#33509; <span class="t-c"><span class="mw-geshi cpp source-cpp">str.<span class="me1">flags</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">&amp;</span> <a href="cpp-io-ios_base-fmtflags.html"><span class="kw1695">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">unitbuf</span></span></a></span></span> &#20026; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> &#21017;&#26512;&#26500;&#20989;&#25968;&#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp">str.<span class="me1">rdbuf</span><span class="br0">(</span><span class="br0">)</span><span class="sy2">-</span><span class="sy1">&gt;</span>pubsync<span class="br0">(</span><span class="br0">)</span></span></span> &#12290;</p>
<p>&#26631;&#20934;&#36755;&#20986;&#23545;&#35937; <span class="t-lc"><a href="cpp-io-cerr.html">std::cerr</a></span> &#21450; <span class="t-lc"><a href="cpp-io-cerr.html">std::wcerr</a></span> &#40664;&#35748;&#24050;&#35774;&#32622;&#20854; <code>unitbuf</code> &#20301;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>str</td>
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<td>&#21040; I/O &#27969;&#30340;&#24341;&#29992;</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><code>str</code> &#65288;&#21040;&#25805;&#32437;&#21518;&#30340;&#27969;&#30340;&#24341;&#29992;&#65289;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
<div class="t-example">
<p>&#26080; std::unitbuf &#25110;&#21478;&#19968;&#26174;&#24335;&#20914;&#20837;&#65292;&#36755;&#20986;&#30456;&#21516;&#65292;&#20294;&#19981;&#23454;&#26102;&#20986;&#29616;&#12290;</p>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;chrono&gt;</span>
<span class="kw1">template</span><span class="sy1">&lt;</span><span class="kw1">typename</span> Diff<span class="sy1">&gt;</span>
<span class="kw4">void</span> log_progress<span class="br0">(</span>Diff d<span class="br0">)</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> <span class="st0">&quot;..(&quot;</span>
<span class="sy1">&lt;&lt;</span> <a href="cpp-chrono-duration-duration_cast.html"><span class="kw1000">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">duration_cast</span></span></a><span class="sy1">&lt;</span><a href="cpp-chrono-duration.html"><span class="kw996">std::<span class="me2">chrono</span><span class="sy4">::</span><span class="me2">milliseconds</span></span></a><span class="sy1">&gt;</span><span class="br0">(</span>d<span class="br0">)</span>.<span class="me1">count</span><span class="br0">(</span><span class="br0">)</span>
<span class="sy1">&lt;&lt;</span> <span class="st0">&quot; ms)..&quot;</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">volatile</span> <span class="kw4">int</span> sink <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> std<span class="sy4">::</span><span class="me2">unitbuf</span><span class="sy4">;</span> <span class="co1">// &#21551;&#29992;&#33258;&#21160;&#20914;&#20837;</span>
<span class="kw4">auto</span> t1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">high_resolution_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> j <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> j <span class="sy1">&lt;</span> <span class="nu0">5</span><span class="sy4">;</span> <span class="sy2">++</span>j<span class="br0">)</span>
<span class="br0">{</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> n <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> n <span class="sy1">&lt;</span> <span class="nu0">10000</span><span class="sy4">;</span> <span class="sy2">++</span>n<span class="br0">)</span>
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">int</span> m <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span> m <span class="sy1">&lt;</span> <span class="nu0">20000</span><span class="sy4">;</span> <span class="sy2">++</span>m<span class="br0">)</span>
sink <span class="sy2">+</span><span class="sy1">=</span> m <span class="sy2">*</span> n<span class="sy4">;</span> <span class="co1">// &#20570;&#19968;&#20123;&#24037;&#20316;</span>
<span class="kw4">auto</span> now <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">chrono</span><span class="sy4">::</span><span class="me2">high_resolution_clock</span><span class="sy4">::</span><span class="me2">now</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
log_progress<span class="br0">(</span>now <span class="sy2">-</span> t1<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> <span class="st0">&#39;<span class="es1">\n</span>&#39;</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">..(450 ms)....(902 ms)....(1352 ms)....(1802 ms)....(2252 ms)..</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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<td>&#20914;&#27927;&#36755;&#20986;&#27969;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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<div><a href="cpp-io-manip-endl.html"><span class="t-lines"><span>endl</span></span></a></div>
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<td>&#36755;&#20986; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">&#39;<span class="es1">\n</span>&#39;</span></span></span> &#24182;&#20914;&#27927;&#36755;&#20986;&#27969;<br />
<span class="t-mark">(&#20989;&#25968;&#27169;&#26495;)</span></td>
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