115 lines
6.4 KiB
HTML
115 lines
6.4 KiB
HTML
<!DOCTYPE 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::strncat</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_byte_strncat skin-cppreference2 action-view cpp-navbar">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>strncat</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-string.html">string</a>‎ | <a href="cpp-string-byte.html">byte</a></span></div>
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<table class="t-dcl-begin">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-cstring.html"><cstring></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span> <span class="sy2">*</span>strncat<span class="br0">(</span> <span class="kw4">char</span> <span class="sy2">*</span>dest, <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>src, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> count <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>后附 <code>src</code> 所指向的字节字符串到 <code>dest</code> 所指向的字节字符串。至多复制 <code>count</code> 个字符。产生的字节字符串是空终止的。</p>
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<p>目标字节字符串必须拥有足够的空间用于连接 <code>dest</code> 和 <code>src</code> 的内容加上终止空字符，但 <code>src</code> 的大小被限制到 <code>count</code> 。</p>
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<p>若字符串重叠则行为未定义。</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>dest</td>
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<td>-</td>
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<td>指向要后附到的空终止字节字符串的指针</td>
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</tr>
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<tr class="t-par">
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<td>src</td>
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<td>-</td>
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<td>指向作为复制来源的字符数组的指针</td>
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</tr>
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<tr class="t-par">
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<td>count</td>
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<td>-</td>
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<td>要复制的最大字符数</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>dest</code></p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>因为 <code>strncat</code> 需要在每次调用时找到 <code>dest</code> 的结尾，故用 <code>strncat</code> 将多个字符串连接成一体是低效的。</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 <cstring></span>
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<span class="co2">#include <cstdio></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> str<span class="br0">[</span><span class="nu0">50</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">"Hello "</span><span class="sy4">;</span>
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<span class="kw4">char</span> str2<span class="br0">[</span><span class="nu0">50</span><span class="br0">]</span> <span class="sy1">=</span> <span class="st0">"World!"</span><span class="sy4">;</span>
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<a href="cpp-string-byte-strcat.html"><span class="kw1142">std::<span class="me2">strcat</span></span></a><span class="br0">(</span>str, str2<span class="br0">)</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">strncat</span><span class="br0">(</span>str, <span class="st0">" Goodbye World!"</span>, <span class="nu0">3</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-c-puts.html"><span class="kw1829">std::<span class="me2">puts</span></span></a><span class="br0">(</span>str<span class="br0">)</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">Hello World! Go</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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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-string-byte-strcat.html"><span class="t-lines"><span>strcat</span></span></a></div>
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</div>
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</td>
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<td>连接两个字符串<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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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-string-byte-strcpy.html"><span class="t-lines"><span>strcpy</span></span></a></div>
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</div>
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</td>
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<td>复制一个字符串给另一个<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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</div>
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<div class="visualClear"></div>
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</body>
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