232 lines
20 KiB
HTML
232 lines
20 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::is_sorted</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_algorithm_is_sorted skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>is_sorted</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-algorithm.html">algorithm</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><a href="cpp-header-algorithm.html"><algorithm></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody class="t-dcl-rev t-dcl-rev-num">
|
|
<tr class="t-dcl-rev-aux">
|
|
<td></td>
|
|
<td rowspan="142">(1)</td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx11 t-until-cxx20">
|
|
<td>
|
|
<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="sy1">></span><br />
|
|
<span class="kw4">bool</span> is_sorted<span class="br0">(</span> ForwardIt first, ForwardIt last <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
|
|
<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<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="sy1">></span><br />
|
|
<span class="kw4">constexpr</span> <span class="kw4">bool</span> is_sorted<span class="br0">(</span> ForwardIt first, ForwardIt last <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx17">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> ExecutionPolicy, <span class="kw1">class</span> ForwardIt <span class="sy1">></span><br />
|
|
<span class="kw4">bool</span> is_sorted<span class="br0">(</span> ExecutionPolicy<span class="sy3">&&</span> policy, ForwardIt first, ForwardIt last <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody class="t-dcl-rev t-dcl-rev-num">
|
|
<tr class="t-dcl-rev-aux">
|
|
<td></td>
|
|
<td rowspan="142">(3)</td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx11 t-until-cxx20">
|
|
<td>
|
|
<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> Compare <span class="sy1">></span><br />
|
|
<span class="kw4">bool</span> is_sorted<span class="br0">(</span> ForwardIt first, ForwardIt last, Compare comp <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span><br />
|
|
<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<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> Compare <span class="sy1">></span><br />
|
|
<span class="kw4">constexpr</span> <span class="kw4">bool</span> is_sorted<span class="br0">(</span> ForwardIt first, ForwardIt last, Compare comp <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
</tbody>
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx17">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> ExecutionPolicy, <span class="kw1">class</span> ForwardIt, <span class="kw1">class</span> Compare <span class="sy1">></span><br /></span>
|
|
<p><span class="kw4">bool</span> is_sorted<span class="br0">(</span> ExecutionPolicy<span class="sy3">&&</span> policy, ForwardIt first, ForwardIt last,<br /></p>
|
|
Compare comp <span class="br0">)</span><span class="sy4">;</span></div>
|
|
</td>
|
|
<td>(4)</td>
|
|
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>检查 <code>[first, last)</code> 中的元素是否以不降序排序。</p>
|
|
<p>若对于任何指向序列的迭代器 <code>it</code> 与任何使得 <code>it + n</code> 为指向序列元素的合法迭代器的非负整数 <code>n</code> ， <span class="t-c"><span class="mw-geshi cpp source-cpp">comp<span class="br0">(</span><span class="sy2">*</span><span class="br0">(</span>it <span class="sy2">+</span> n<span class="br0">)</span>, <span class="sy2">*</span>it<span class="br0">)</span></span></span> 求值为 <code>false</code> ，则称序列相对于 <code>comp</code> <i>已排序</i>。</p>
|
|
<div class="t-li1"><span class="t-li">1)</span> 用 <code>operator<</code> 比较元素。</div>
|
|
<div class="t-li1"><span class="t-li">3)</span> 用给定的二元比较函数 <code>comp</code> 比较元素。</div>
|
|
<div class="t-li1"><span class="t-li">2,4)</span> 同 <span class="t-v">(1,3)</span> ，但按照 <code>policy</code> 执行。这些重载仅若 <span class="t-rev-inl t-until-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-algorithm-is_execution_policy.html"><span class="kw1564">std::<span class="me2">is_execution_policy_v</span></span></a><span class="sy1"><</span><a href="cpp-types-decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>ExecutionPolicy<span class="sy1">>></span></span></span></span> <span><span class="t-mark-rev t-until-cxx20">(C++20 前)</span></span></span><span class="t-rev-inl t-since-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-algorithm-is_execution_policy.html"><span class="kw1564">std::<span class="me2">is_execution_policy_v</span></span></a><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">remove_cvref_t</span><span class="sy1"><</span>ExecutionPolicy<span class="sy1">>></span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> 为 true 才参与重载决议。</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>first, last</td>
|
|
<td>-</td>
|
|
<td>要检验的元素范围</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>policy</td>
|
|
<td>-</td>
|
|
<td>所用的执行策略。细节见<a href="cpp-algorithm-execution_policy_tag_t.html">执行策略</a>。</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>comp</td>
|
|
<td>-</td>
|
|
<td>比较函数对象（即满足<a href="cpp-named_req-Compare.html"><span style="font-style:italic">比较</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(Compare)</span></a> 概念的对象），若第一参数<i>小于</i>（即<i>先</i>序于）第二参数则返回 ​<span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 。<br />
|
|
<p>比较函数的签名应等价于如下：</p>
|
|
<p><span class="t-cc"><span class="mw-geshi cpp source-cpp"> <span class="kw4">bool</span> cmp<span class="br0">(</span><span class="kw4">const</span> Type1 <span class="sy3">&</span>a, <span class="kw4">const</span> Type2 <span class="sy3">&</span>b<span class="br0">)</span><span class="sy4">;</span></span></span></p>
|
|
<p>虽然签名不必有 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="sy3">&</span></span></span> ，函数也不能修改传递给它的对象，而且必须接受（可为 const 的）类型 <code>Type1</code> 与 <code>Type2</code> 的值，无关乎<a href="cpp-language-value_category.html">值类别</a>（从而不允许 <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1 <span class="sy3">&</span></span></span> <span class="t-rev-inl t-since-cxx11"><span>，亦不允许 <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> ，除非 <code>Type1</code> 的移动等价于复制</span> <span><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></span></span>）。<br />
|
|
类型 <span class="t-c"><span class="mw-geshi cpp source-cpp">Type1</span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp">Type2</span></span> 必须使得 <span class="t-c"><span class="mw-geshi cpp source-cpp">ForwardIt</span></span> 类型的对象能在解引用后隐式转换到这两个类型。 ​</p>
|
|
</td>
|
|
</tr>
|
|
<tr class="t-par-hitem">
|
|
<td colspan="3">类型要求</td>
|
|
</tr>
|
|
<tr class="t-par-req">
|
|
<td colspan="3">-
|
|
<div class="spacer"></div>
|
|
<code>ForwardIt</code> 必须满足<a href="cpp-named_req-ForwardIterator.html"><span style="font-style:italic">老式向前迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyForwardIterator)</span></a> 的要求。</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>若范围中的元素已按不降序排序则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 。</p>
|
|
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
|
|
<p>与 <code>first</code> 和 <code>last</code> 间的距离成线性。</p>
|
|
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
|
|
<p>拥有名为 <code>ExecutionPolicy</code> 的模板形参的重载按下列方式报告错误：</p>
|
|
<ul>
|
|
<li>若作为算法一部分调用的函数的执行抛出异常，且 <code>ExecutionPolicy</code> 为<a href="cpp-algorithm-execution_policy_tag_t.html">标准策略</a>之一，则调用 <span class="t-lc"><a href="cpp-error-terminate.html">std::terminate</a></span> 。对于任何其他 <code>ExecutionPolicy</code> ，行为是实现定义的。</li>
|
|
<li>若算法无法分配内存，则抛出 <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></span> 。</li>
|
|
</ul>
|
|
<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">可能的实现</span></h3>
|
|
<table class="eq-fun-cpp-table">
|
|
<tr>
|
|
<th>版本一</th>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> ForwardIt<span class="sy1">></span>
|
|
<span class="kw4">bool</span> is_sorted<span class="br0">(</span>ForwardIt first, ForwardIt last<span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw1">return</span> <a href="cpp-algorithm-is_sorted_until.html"><span class="kw1616">std::<span class="me2">is_sorted_until</span></span></a><span class="br0">(</span>first, last<span class="br0">)</span> <span class="sy1">==</span> last<span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<th>版本二</th>
|
|
</tr>
|
|
<tr>
|
|
<td>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> ForwardIt, <span class="kw1">class</span> Compare<span class="sy1">></span>
|
|
<span class="kw4">bool</span> is_sorted<span class="br0">(</span>ForwardIt first, ForwardIt last, Compare comp<span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw1">return</span> <a href="cpp-algorithm-is_sorted_until.html"><span class="kw1616">std::<span class="me2">is_sorted_until</span></span></a><span class="br0">(</span>first, last, comp<span class="br0">)</span> <span class="sy1">==</span> last<span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p><code>std::is_sorted</code> 对空范围及长为 1 的范围均返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 。</p>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co2">#include <iostream></span>
|
|
<span class="co2">#include <algorithm></span>
|
|
<span class="co2">#include <iterator></span>
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw4">int</span> digits<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span><span class="nu0">3</span>, <span class="nu0">1</span>, <span class="nu0">4</span>, <span class="nu0">1</span>, <span class="nu0">5</span><span class="br0">}</span><span class="sy4">;</span>
|
|
|
|
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">auto</span> i <span class="sy4">:</span> digits<span class="br0">)</span> <a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> i <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">": is_sorted: "</span> <span class="sy1"><<</span> <a href="cpp-io-manip-boolalpha.html"><span class="kw1763">std::<span class="me2">boolalpha</span></span></a>
|
|
<span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">is_sorted</span><span class="br0">(</span><a href="cpp-iterator-begin.html"><span class="kw676">std::<span class="me2">begin</span></span></a><span class="br0">(</span>digits<span class="br0">)</span>, <a href="cpp-iterator-end.html"><span class="kw680">std::<span class="me2">end</span></span></a><span class="br0">(</span>digits<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>
|
|
|
|
<a href="cpp-algorithm-sort.html"><span class="kw1617">std::<span class="me2">sort</span></span></a><span class="br0">(</span><a href="cpp-iterator-begin.html"><span class="kw676">std::<span class="me2">begin</span></span></a><span class="br0">(</span>digits<span class="br0">)</span>, <a href="cpp-iterator-end.html"><span class="kw680">std::<span class="me2">end</span></span></a><span class="br0">(</span>digits<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">auto</span> i <span class="sy4">:</span> digits<span class="br0">)</span> <a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> i <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">": is_sorted: "</span>
|
|
<span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">is_sorted</span><span class="br0">(</span><a href="cpp-iterator-begin.html"><span class="kw676">std::<span class="me2">begin</span></span></a><span class="br0">(</span>digits<span class="br0">)</span>, <a href="cpp-iterator-end.html"><span class="kw680">std::<span class="me2">end</span></span></a><span class="br0">(</span>digits<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>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">3 1 4 1 5 : is_sorted: false
|
|
1 1 3 4 5 : is_sorted: true</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-is_sorted_until.html"><span class="t-lines"><span>is_sorted_until</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>找出最大的已排序子范围<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|