121 lines
9.1 KiB
HTML
121 lines
9.1 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::skipws, std::noskipws</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_manip_skipws skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>skipws, <span style="font-size:0.7em; line-height:130%">std::</span>noskipws</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-manip.html">manip</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-ios.html"><ios></a></code></div>
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<td></td>
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<td></td>
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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">&</span> skipws<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">&</span> str <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"><a href="cpp-io-ios_base.html"><span class="kw1669">std::<span class="me2">ios_base</span></span></a><span class="sy3">&</span> noskipws<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">&</span> str <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
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<td class="t-dcl-nopad"></td>
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<p>启用或禁用有格式输入函数所做的跳过前导空白符（默认启用）。在输出上无效果。</p>
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<div class="t-li1"><span class="t-li">1)</span> 如同用调用 <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="kw1694">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">skipws</span></span></a><span class="br0">)</span></span></span> 启用流 <code>str</code> 中的 <code>skipws</code> 标志</div>
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<div class="t-li1"><span class="t-li">2)</span> 如同用调用 <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="kw1694">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">skipws</span></span></a><span class="br0">)</span></span></span> 禁用流 <code>str</code> 中的 <code>skipws</code> 标志</div>
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<p>跳过空白符由 <span class="t-lc"><a href="cpp-io-basic_istream-sentry.html">std::basic_istream::sentry</a></span> 的构造函数进行，它读取并舍弃由流所感染的 locale 的 <span class="t-lc"><a href="cpp-locale-ctype.html">std::ctype</a></span> 平面分类为空白符的字符。</p>
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<p>这是一个 I/O 操纵符，可用如 <span class="t-c"><span class="mw-geshi cpp source-cpp">out <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">noskipws</span></span></span> 的表达式对任何 <span class="t-lc"><a href="cpp-io-basic_ostream.html">std::basic_ostream</a></span> 类型的 <code>out</code> 或用如 <span class="t-c"><span class="mw-geshi cpp source-cpp">in <span class="sy1">>></span> std<span class="sy4">::</span><span class="me2">noskipws</span></span></span> 的表达式对任何 <span class="t-lc"><a href="cpp-io-basic_istream.html">std::basic_istream</a></span> 类型的 <code>in</code> 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>str</td>
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<td>-</td>
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<td>到 I/O 流的引用</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><code>str</code> （到操纵后的流的引用）</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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<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 <iostream></span>
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<span class="co2">#include <sstream></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> c1, c2, c3<span class="sy4">;</span>
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<a href="cpp-io-basic_istringstream.html"><span class="kw1735">std::<span class="me2">istringstream</span></span></a><span class="br0">(</span><span class="st0">"a b c"</span><span class="br0">)</span> <span class="sy1">>></span> c1 <span class="sy1">>></span> c2 <span class="sy1">>></span> c3<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">"Default behavior: c1 = "</span> <span class="sy1"><<</span> c1 <span class="sy1"><<</span> <span class="st0">" c2 = "</span> <span class="sy1"><<</span> c2 <span class="sy1"><<</span> <span class="st0">" c3 = "</span> <span class="sy1"><<</span> c3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<a href="cpp-io-basic_istringstream.html"><span class="kw1735">std::<span class="me2">istringstream</span></span></a><span class="br0">(</span><span class="st0">"a b c"</span><span class="br0">)</span> <span class="sy1">>></span> std<span class="sy4">::</span><span class="me2">noskipws</span> <span class="sy1">>></span> c1 <span class="sy1">>></span> c2 <span class="sy1">>></span> c3<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">"noskipws behavior: c1 = "</span> <span class="sy1"><<</span> c1 <span class="sy1"><<</span> <span class="st0">" c2 = "</span> <span class="sy1"><<</span> c2 <span class="sy1"><<</span> <span class="st0">" c3 = "</span> <span class="sy1"><<</span> c3 <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>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">Default behavior: c1 = a c2 = b c3 = c
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noskipws behavior: c1 = a c2 = c3 = b</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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<div class="t-dsc-member-div">
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<div><a href="cpp-io-manip-resetiosflags.html"><span class="t-lines"><span>resetiosflags</span></span></a></div>
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</div>
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</td>
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<td>清除指定的 ios_base 标志<br />
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<span class="t-mark">(函数)</span></td>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-manip-setiosflags.html"><span class="t-lines"><span>setiosflags</span></span></a></div>
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</div>
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</td>
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<td>设置指定的 ios_base 标志<br />
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<span class="t-mark">(函数)</span></td>
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<tr class="t-dsc">
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-manip-ws.html"><span class="t-lines"><span>ws</span></span></a></div>
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</div>
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</td>
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<td>消耗空白符<br />
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<span class="t-mark">(函数模板)</span></td>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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