109 lines
8.5 KiB
HTML
109 lines
8.5 KiB
HTML
<!DOCTYPE html>
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<title>std::basic_ostream<CharT,Traits>::put</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_io_basic_ostream_put 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::basic_ostream<CharT,Traits>::</span>put</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-basic_ostream.html">basic ostream</a></span></div>
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<div><span class="mw-geshi cpp source-cpp">basic_ostream<span class="sy3">&</span> put<span class="br0">(</span> char_type ch <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>表现为<a href="cpp-named_req-UnformattedOutputFunction.html"><span style="font-style:italic">无格式输出函数</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(UnformattedOutputFunction)</span></a> 。构造并检查 sentry 对象后，写字符 <code>ch</code> 到输出流。</p>
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<p>若输出因任何原因失败，则设置 <code>badbit</code> 。</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>ch</td>
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<td>-</td>
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<td>要写入的字符</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"><span class="sy2">*</span>this</span></span></p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>此函数不对 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">signed</span> <span class="kw4">char</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> 类型重载，不同于有格式的 <a href="cpp-io-basic_ostream-operator_ltlt2.html">operator<<</a> 。</p>
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<p>不同于有格式输出函数，若输出失败，则此函数不设置 <code>failbit</code> 。</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 <fstream></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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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a>.<span class="me1">put</span><span class="br0">(</span><span class="st0">'a'</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 正常用法</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">put</span><span class="br0">(</span><span class="st0">'<span class="es1">\n</span>'</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-basic_ofstream.html"><span class="kw1733">std::<span class="me2">ofstream</span></span></a> s<span class="br0">(</span><span class="st0">"/does/not/exist/"</span><span class="br0">)</span><span class="sy4">;</span>
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s.<span class="me1">clear</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 假装流是好的</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">"Unformatted output: "</span><span class="sy4">;</span>
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s.<span class="me1">put</span><span class="br0">(</span><span class="st0">'c'</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 这将设置 badbit ，但非 failbit</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">" fail="</span> <span class="sy1"><<</span> <span class="kw4">bool</span><span class="br0">(</span>s.<span class="me1">rdstate</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">&</span> s.<span class="me1">failbit</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">" bad="</span> <span class="sy1"><<</span> s.<span class="me1">bad</span><span class="br0">(</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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s.<span class="me1">clear</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">"Formatted output: "</span><span class="sy4">;</span>
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s <span class="sy1"><<</span> <span class="st0">'c'</span><span class="sy4">;</span> <span class="co1">// 这将设置 badbit 和 failbit</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">" fail="</span> <span class="sy1"><<</span> <span class="kw4">bool</span><span class="br0">(</span>s.<span class="me1">rdstate</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">&</span> s.<span class="me1">failbit</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">" bad="</span> <span class="sy1"><<</span> s.<span class="me1">bad</span><span class="br0">(</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">a
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Unformatted output: fail=0 bad=1
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Formatted output: fail=1 bad=1</pre></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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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_ostream-operator_ltlt2.html"><span class="t-lines"><span>operator<<<span class="t-dsc-small">(std::basic_ostream)</span></span></span></a></div>
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</div>
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</td>
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<td>插入字符数据<br />
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<span class="t-mark">(函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-basic_ostream-write.html"><span class="t-lines"><span>write</span></span></a></div>
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</div>
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</td>
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<td>插入字符块<br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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</table>
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<div class="visualClear"></div>
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