189 lines
14 KiB
HTML
189 lines
14 KiB
HTML
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<title>std::default_searcher</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_utility_functional_default_searcher 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>default_searcher</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-utility.html">utility</a>‎ | <a href="cpp-utility-functional.html">functional</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-functional.html"><functional></a></code></div>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> ForwardIt, <span class="kw1">class</span> BinaryPredicate <span class="sy1">=</span> <a href="cpp-utility-functional-equal_to.html"><span class="kw1035">std::<span class="me2">equal_to</span></span></a><span class="sy1"><></span> <span class="sy1">></span><br />
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<span class="kw1">class</span> default_searcher<span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<p>适合用于 <span class="t-lc"><a href="cpp-algorithm-search.html">std::search</a></span> 的<a href="https://zh.cppreference.com/mwiki/index.php?title=cpp/named_req/Searcher&action=edit&redlink=1" class="new" title="cpp/named req/Searcher（页面不存在）"><span style="font-style:italic">搜索器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Searcher)</span></a> 重载的类，它将搜索操作委派到 C++17 前标准库的 <span class="t-lc"><a href="cpp-algorithm-search.html">std::search</a></span> 。</p>
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<p><code>default_searcher</code> 是为<a href="cpp-named_req-CopyConstructible.html"><span style="font-style:italic">可复制构造</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyConstructible)</span></a> 及<a href="cpp-named_req-CopyAssignable.html"><span style="font-style:italic">可复制赋值</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(CopyAssignable)</span></a> 。</p>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
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<h2><span class="mw-headline" id="std::default_searcher::default_searcher"><span style="font-size:0.7em; line-height:130%">std::default_searcher::</span>default_searcher</span></h2>
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<div><span class="mw-geshi cpp source-cpp">default_searcher<span class="br0">(</span> ForwardIt pat_first,<br /></span>
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<p> ForwardIt pat_last,<br /></p>
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BinaryPredicate pred <span class="sy1">=</span> BinaryPredicate<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> default_searcher<span class="br0">(</span> ForwardIt pat_first,<br /></span>
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<p> ForwardIt pat_last,<br /></p>
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BinaryPredicate pred <span class="sy1">=</span> BinaryPredicate<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<p>以存储 <code>pat_first</code> 、 <code>pat_last</code> 及 <code>pred</code> 的副本构造一个 <code>default_searcher</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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<td>pat_first, pat_last</td>
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<td>-</td>
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<td>指代要搜索的串的一对迭代器</td>
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<td>pred</td>
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<td>-</td>
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<td>用于检测相等的可调用对象</td>
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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>任何 <code>BinaryPredicate</code> 或 <code>ForwardIt</code> 的复制构造函数可能抛出的异常。</p>
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<h2><span class="mw-headline" id="std::default_searcher::operator.28.29"><span style="font-size:0.7em; line-height:130%">std::default_searcher::</span>operator()</span></h2>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> ForwardIt2 <span class="sy1">></span><br /></span>
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<p><a href="cpp-utility-pair.html"><span class="kw1094">std::<span class="me2">pair</span></span></a><span class="sy1"><</span>ForwardIt2, ForwardIt2<span class="sy1">></span><br /></p>
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operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> ForwardIt2 first, ForwardIt2 last <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
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<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> ForwardIt2 <span class="sy1">></span><br /></span>
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<p><span class="kw4">constexpr</span> <a href="cpp-utility-pair.html"><span class="kw1094">std::<span class="me2">pair</span></span></a><span class="sy1"><</span>ForwardIt2, ForwardIt2<span class="sy1">></span><br /></p>
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operator<span class="br0">(</span><span class="br0">)</span><span class="br0">(</span> ForwardIt2 first, ForwardIt2 last <span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<p><span class="t-lc"><a href="cpp-algorithm-search.html">std::search</a></span> 的搜索器 (<span style="font-style:italic">搜索器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Searcher)</span> ) 重载调用此函数以进行用此搜索器的搜索。</p>
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<p>返回一对迭代器 <code>i, j</code> ，其中 <code>i</code> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-algorithm-search.html"><span class="kw1578">std::<span class="me2">search</span></span></a><span class="br0">(</span>first, last, pat_first, pat_last, pred<span class="br0">)</span></span></span> 且 <code>j</code> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-iterator-next.html"><span class="kw674">std::<span class="me2">next</span></span></a><span class="br0">(</span>i, <a href="cpp-iterator-distance.html"><span class="kw673">std::<span class="me2">distance</span></span></a><span class="br0">(</span>pat_first, pat_last<span class="br0">)</span><span class="br0">)</span></span></span> ，除非 <code>std::search</code> 返回 <code>last</code> （无匹配），此情况下 <code>j</code> 也等于 <code>last</code> 。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0_2">参数</span></h3>
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<td>first, last</td>
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<td>-</td>
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<td>指代要检验的字符串的一对迭代器</td>
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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>分别指向 <span class="texhtml" style="white-space: nowrap;">[first, last)</span> 中首位置和尾后一位的一对迭代器，其中定位的子序列按 <code>pred</code> 所定义与 <span class="texhtml" style="white-space: nowrap;">[pat_first, pat_last)</span> 比较相等，其他情况返回一对 <code>last</code> 的副本。</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 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 <string></span>
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<span class="co2">#include <algorithm></span>
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<span class="co2">#include <functional></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-string-basic_string.html"><span class="kw1228">std::<span class="me2">string</span></span></a> in <span class="sy1">=</span> <span class="st0">"Lorem ipsum dolor sit amet, consectetur adipiscing elit,"</span>
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<span class="st0">" sed do eiusmod tempor incididunt ut labore et dolore magna aliqua"</span><span class="sy4">;</span>
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<a href="cpp-string-basic_string.html"><span class="kw1228">std::<span class="me2">string</span></span></a> needle <span class="sy1">=</span> <span class="st0">"pisci"</span><span class="sy4">;</span>
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<span class="kw4">auto</span> it <span class="sy1">=</span> <a href="cpp-algorithm-search.html"><span class="kw1578">std::<span class="me2">search</span></span></a><span class="br0">(</span>in.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, in.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>,
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std<span class="sy4">::</span><span class="me2">default_searcher</span><span class="br0">(</span>
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needle.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, needle.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>it <span class="sy3">!</span><span class="sy1">=</span> in.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1756">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"The string "</span> <span class="sy1"><<</span> needle <span class="sy1"><<</span> <span class="st0">" found at offset "</span>
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<span class="sy1"><<</span> it <span class="sy2">-</span> in.<span class="me1">begin</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="kw1">else</span>
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<a href="cpp-io-cout.html"><span class="kw1756">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"The string "</span> <span class="sy1"><<</span> needle <span class="sy1"><<</span> <span class="st0">" not found<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></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">The string pisci found at offset 43</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-algorithm-search.html"><span class="t-lines"><span>search</span></span></a></div>
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</div>
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</td>
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<td>搜索一个元素范围<br />
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<span class="t-mark">(函数模板)</span></td>
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</tr>
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