143 lines
14 KiB
HTML
143 lines
14 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::left, std::right, std::internal</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_manip_left 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>left, <span style="font-size:0.7em; line-height:130%">std::</span>right, <span style="font-size:0.7em; line-height:130%">std::</span>internal</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>
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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> left<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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<td class="t-dcl-nopad"></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> right<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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<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> internal<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>(3)</td>
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<td class="t-dcl-nopad"></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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</tbody>
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<p>修改填充字符的默认定位。 <code>left</code> 与 <code>right</code> 应用到任何输出，而 <code>internal</code> 应用到整数、浮点和货币输出。在输入时无效果。</p>
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<p>1) 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="kw1683">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">left</span></span></a>, <a href="cpp-io-ios_base-fmtflags.html"><span class="kw1686">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">adjustfield</span></span></a><span class="br0">)</span></span></span> ，设置流 <code>str</code> 的 <code>adjustfield</code> 为 <code>left</code></p>
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<p>2) 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="kw1684">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">right</span></span></a>, <a href="cpp-io-ios_base-fmtflags.html"><span class="kw1686">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">adjustfield</span></span></a><span class="br0">)</span></span></span> ，设置流 <code>str</code> 的 <code>adjustfield</code> 为 <code>right</code></p>
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<p>3) 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="kw1685">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">internal</span></span></a>, <a href="cpp-io-ios_base-fmtflags.html"><span class="kw1686">std::<span class="me2">ios_base</span><span class="sy4">::</span><span class="me2">adjustfield</span></span></a><span class="br0">)</span></span></span> ，设置流 <code>str</code> 的 <code>adjustfield</code> 为 <code>internal</code></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">left</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">left</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 <iomanip></span>
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<span class="co2">#include <locale></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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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>.<span class="me1">imbue</span><span class="br0">(</span><a href="cpp-locale-locale.html"><span class="kw1891">std::<span class="me2">locale</span></span></a><span class="br0">(</span><span class="st0">"en_US.utf8"</span><span class="br0">)</span><span class="br0">)</span><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">"Left fill:<span class="es1">\n</span>"</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">left</span> <span class="sy1"><<</span> <a href="cpp-io-manip-setfill.html"><span class="kw1792">std::<span class="me2">setfill</span></span></a><span class="br0">(</span><span class="st0">'*'</span><span class="br0">)</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="sy2">-</span><span class="nu16">1.23</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <a href="cpp-io-manip-hex.html"><span class="kw1779">std::<span class="me2">hex</span></span></a> <span class="sy1"><<</span> <a href="cpp-io-manip-showbase.html"><span class="kw1766">std::<span class="me2">showbase</span></span></a> <span class="sy1"><<</span> <span class="nu0">42</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <a href="cpp-io-manip-put_money.html"><span class="kw1796">std::<span class="me2">put_money</span></span></a><span class="br0">(</span><span class="nu0">123</span>, <span class="kw2">true</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"<span class="es1">\n</span><span class="es1">\n</span>"</span><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">"Internal fill:<span class="es1">\n</span>"</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">internal</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="sy2">-</span><span class="nu16">1.23</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="nu0">42</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <a href="cpp-io-manip-put_money.html"><span class="kw1796">std::<span class="me2">put_money</span></span></a><span class="br0">(</span><span class="nu0">123</span>, <span class="kw2">true</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">"<span class="es1">\n</span><span class="es1">\n</span>"</span><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">"Right fill:<span class="es1">\n</span>"</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">right</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="sy2">-</span><span class="nu16">1.23</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="nu0">42</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <a href="cpp-io-manip-setw.html"><span class="kw1794">std::<span class="me2">setw</span></span></a><span class="br0">(</span><span class="nu0">12</span><span class="br0">)</span> <span class="sy1"><<</span> <a href="cpp-io-manip-put_money.html"><span class="kw1796">std::<span class="me2">put_money</span></span></a><span class="br0">(</span><span class="nu0">123</span>, <span class="kw2">true</span><span class="br0">)</span> <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">Left fill:
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-1.23*******
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0x2a********
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USD *1.23***
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Internal fill:
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-*******1.23
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0x********2a
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USD ****1.23
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Right fill:
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*******-1.23
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********0x2a
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***USD *1.23</pre></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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<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-manip-setw.html"><span class="t-lines"><span>setw</span></span></a></div>
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</div>
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</td>
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<td>更改下个输入/输出域的宽度<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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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-setfill.html"><span class="t-lines"><span>setfill</span></span></a></div>
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</div>
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</td>
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<td>更改填充字符<br />
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<span class="t-mark">(函数模板)</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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