72 lines
4.1 KiB
HTML
72 lines
4.1 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::char_traits<CharT>::compare</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_char_traits_compare skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::char_traits<CharT>::</span>compare</h1>
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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-char_traits.html">char traits</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">static</span> <span class="kw4">int</span> compare<span class="br0">(</span> <span class="kw4">const</span> char_type<span class="sy2">*</span> s1, <span class="kw4">const</span> char_type<span class="sy2">*</span> s2, <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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<td><span class="t-mark-rev t-until-cxx17">(C++17 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">static</span> <span class="kw4">constexpr</span> <span class="kw4">int</span> compare<span class="br0">(</span> <span class="kw4">const</span> char_type<span class="sy2">*</span> s1, <span class="kw4">const</span> char_type<span class="sy2">*</span> s2, <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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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<p>比较字符串 <code>s1</code> 与 <code>s2</code> 的首 <code>count</code> 个字节，比较按字典序进行。</p>
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<p>若 <code>count</code> 为零，则认为字符串相等。</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>s1, s2</td>
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<td>-</td>
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<td>指向要比较的字符串的指针</td>
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</tr>
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<tr class="t-par">
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<td>count</td>
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<td>-</td>
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<td>要比较来自每个字符串的字符数</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>若 <code>s1</code> <i>小于</i> <code>s2</code> 则为负值。</p>
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<p>若 <code>s1</code> <i>等于</i> <code>s2</code> 则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> 。</p>
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<p>若 <code>s1</code> <i>大于</i> <code>s2</code> 则为正值。</p>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>不抛出。</p>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
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<p>与 <code>count</code> 成线性。</p>
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