319 lines
33 KiB
HTML
319 lines
33 KiB
HTML
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<title>std::adjacent_difference</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_algorithm_adjacent_difference 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>adjacent_difference</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-algorithm.html">algorithm</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-numeric.html"><numeric></a></code></div>
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<td rowspan="142">(1)</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> InputIt, <span class="kw1">class</span> OutputIt <span class="sy1">></span><br /></span>
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<p>OutputIt adjacent_difference<span class="br0">(</span> InputIt first, InputIt last,<br /></p>
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OutputIt d_first <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
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<td><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> InputIt, <span class="kw1">class</span> OutputIt <span class="sy1">></span><br /></span>
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<p><span class="kw4">constexpr</span> OutputIt adjacent_difference<span class="br0">(</span> InputIt first, InputIt last,<br /></p>
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OutputIt d_first <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</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> ExecutionPolicy, <span class="kw1">class</span> ForwardIt1, <span class="kw1">class</span> ForwardIt2 <span class="sy1">></span><br /></span>
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<p>ForwardIt2 adjacent_difference<span class="br0">(</span> ExecutionPolicy<span class="sy3">&&</span> policy, ForwardIt1 first, ForwardIt1 last,<br /></p>
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ForwardIt2 d_first <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<td rowspan="142">(3)</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> InputIt, <span class="kw1">class</span> OutputIt, <span class="kw1">class</span> BinaryOperation <span class="sy1">></span><br /></span>
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<p>OutputIt adjacent_difference<span class="br0">(</span> InputIt first, InputIt last,<br /></p>
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OutputIt d_first, BinaryOperation op <span class="br0">)</span><span class="sy4">;</span></div>
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<td class="t-dcl-nopad"></td>
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<td><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> InputIt, <span class="kw1">class</span> OutputIt, <span class="kw1">class</span> BinaryOperation <span class="sy1">></span><br /></span>
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<p><span class="kw4">constexpr</span> OutputIt adjacent_difference<span class="br0">(</span> InputIt first, InputIt last,<br /></p>
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OutputIt d_first, BinaryOperation op <span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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</tbody>
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<tbody>
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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> ExecutionPolicy, <span class="kw1">class</span> ForwardIt1, <span class="kw1">class</span> ForwardIt2, <span class="kw1">class</span> BinaryOperation <span class="sy1">></span><br /></span>
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<p>ForwardIt2 adjacent_difference<span class="br0">(</span> ExecutionPolicy<span class="sy3">&&</span> policy, ForwardIt1 first, ForwardIt1 last,<br /></p>
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ForwardIt2 d_first, BinaryOperation op <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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<p>计算 <code>[first, last)</code> 范围中每对相邻元素的第二个和第一个的差，并写入它们到始于 <code>d_first + 1</code> 的范围。写入不修改的 <code>*first</code> 副本到 <code>*d_first</code> 。</p>
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<div class="t-li1"><span class="t-li">1,3)</span> 首先，创建类型为 <code>InputIt</code> 的 value_type 的积累器 <code>acc</code> ，以 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>first</span></span> 初始化，并赋值为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>d_first</span></span> 的结果。然后，对于 <code>[first + 1, last)</code> 中按顺序的每个迭代器 <code>i</code> ，创建类型为 <code>InputIt</code> 的 value_type 的对象 <code>val</code> ，以 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>i</span></span> 初始化，计算 <span class="t-rev-inl t-until-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp">val <span class="sy2">-</span> acc</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">val <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> （重载 <span class="t-v">(1)</span> ）或 <span class="t-rev-inl t-until-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp">op<span class="br0">(</span>val, acc<span class="br0">)</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">op<span class="br0">(</span>val, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span><span class="br0">)</span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> （重载 <span class="t-v">(3)</span> ），赋值结果到 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span><span class="br0">(</span>d_first <span class="sy2">+</span> <span class="br0">(</span>i <span class="sy2">-</span> first<span class="br0">)</span><span class="br0">)</span></span></span> ，并从 <code>val</code> 移动赋值到 <code>acc</code> 。</div>
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<div class="t-li1"><span class="t-li"></span> <span class="t-c"><span class="mw-geshi cpp source-cpp">first</span></span> 可以等于 <span class="t-c"><span class="mw-geshi cpp source-cpp">d_first</span></span> 。</div>
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<div class="t-li1"><span class="t-li">2,4)</span> 进行 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>d_first <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span></span></span> 。对每个 <code>[1, last - first - 1]</code> 中的 <code>d</code> ，赋值 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span><span class="br0">(</span>first <span class="sy2">+</span> d<span class="br0">)</span> <span class="sy2">-</span> <span class="sy2">*</span><span class="br0">(</span>first <span class="sy2">+</span> d <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span></span></span> （重载 <span class="t-v">(2)</span> ）或 <span class="t-c"><span class="mw-geshi cpp source-cpp">op<span class="br0">(</span><span class="sy2">*</span><span class="br0">(</span>first <span class="sy2">+</span> d<span class="br0">)</span>, <span class="sy2">*</span><span class="br0">(</span>first <span class="sy2">+</span> d <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span></span></span> （重载 <span class="t-v">(4)</span> ）给 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span><span class="br0">(</span>d_first <span class="sy2">+</span> d<span class="br0">)</span></span></span> 。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>
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<div class="t-li1"><span class="t-li"></span> 若输入与输出范围以任何方式重叠则行为未定义。</div>
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<p><br />
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等价操作：</p>
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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="sy2">*</span><span class="br0">(</span>d_first<span class="br0">)</span> <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
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<span class="sy2">*</span><span class="br0">(</span>d_first<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span> <span class="sy1">=</span> <span class="sy2">*</span><span class="br0">(</span>first<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span> <span class="sy2">-</span> <span class="sy2">*</span><span class="br0">(</span>first<span class="br0">)</span><span class="sy4">;</span>
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<span class="sy2">*</span><span class="br0">(</span>d_first<span class="sy2">+</span><span class="nu0">2</span><span class="br0">)</span> <span class="sy1">=</span> <span class="sy2">*</span><span class="br0">(</span>first<span class="sy2">+</span><span class="nu0">2</span><span class="br0">)</span> <span class="sy2">-</span> <span class="sy2">*</span><span class="br0">(</span>first<span class="sy2">+</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="sy2">*</span><span class="br0">(</span>d_first<span class="sy2">+</span><span class="nu0">3</span><span class="br0">)</span> <span class="sy1">=</span> <span class="sy2">*</span><span class="br0">(</span>first<span class="sy2">+</span><span class="nu0">3</span><span class="br0">)</span> <span class="sy2">-</span> <span class="sy2">*</span><span class="br0">(</span>first<span class="sy2">+</span><span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span>
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...</pre></div>
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</div>
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<p><code>op</code> 必须无副效应。</p>
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</td>
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<td><span class="t-mark-rev t-until-cxx11">(C++11 前)</span></td>
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</tr>
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<tr class="t-rev t-since-cxx11">
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<p><code>op</code> 必须不非法化涉及范围的任何迭代器，含尾迭代器，或修改该范围的任何元素。</p>
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</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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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>first, last</td>
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<td>-</td>
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<td>元素范围</td>
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</tr>
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<tr class="t-par">
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<td>d_first</td>
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<td>-</td>
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<td>目标范围的起始</td>
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</tr>
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<tr class="t-par">
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<td>policy</td>
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<td>-</td>
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<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>
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<tr class="t-par">
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<td>op</td>
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<td>-</td>
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<td>被使用的二元函数对象。<br />
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<p>该函数的签名应当等价于：</p>
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<p><span class="t-cc"><span class="mw-geshi cpp source-cpp"> Ret fun<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>
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<p>签名中并不需要有 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> <span class="sy3">&</span></span></span>。<br />
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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">iterator_traits<span class="sy1"><</span>InputIt<span class="sy1">></span><span class="sy4">::</span><span class="me2">value_type</span></span></span> 类型的对象能隐式转换到这两个类型。 类型 <span class="t-c"><span class="mw-geshi cpp source-cpp">Ret</span></span> 必须使得 <span class="t-c"><span class="mw-geshi cpp source-cpp">OutputIt</span></span> 类型对象能被解引用并能被赋 <span class="t-c"><span class="mw-geshi cpp source-cpp">Ret</span></span> 类型值。 ​</p>
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</td>
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<tr class="t-par-hitem">
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<td colspan="3">类型要求</td>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>InputIt</code> 必须满足<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">老式输入迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyInputIterator)</span></a> 的要求。InputIt 的值类型必须<a href="cpp-named_req-MoveAssignable.html"><span style="font-style:italic">可移动赋值</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(MoveAssignable)</span></a> 且可从 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>first</span></span> 的类型构造</td>
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</tr>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>OutputIt</code> 必须满足<a href="cpp-named_req-OutputIterator.html"><span style="font-style:italic">老式输出迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyOutputIterator)</span></a> 的要求。<span class="t-c"><span class="mw-geshi cpp source-cpp">acc</span></span> （积累的值）和 <span class="t-rev-inl t-until-cxx20"><span><span class="t-c"><span class="mw-geshi cpp source-cpp">val <span class="sy2">-</span> acc</span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">op<span class="br0">(</span>val, acc<span class="br0">)</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">val <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">op<span class="br0">(</span>val, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span><span class="br0">)</span></span></span></span> <span><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></span></span> 结果都必须可写入 <code>OutputIt</code></td>
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</tr>
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<tr class="t-par-req">
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<td colspan="3">-
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<div class="spacer"></div>
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<code>ForwardIt1, ForwardIt2</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。<span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>first</span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>first <span class="sy2">-</span> <span class="sy2">*</span>first</span></span> （对于 <span class="t-v">(2)</span> ）和 <span class="t-c"><span class="mw-geshi cpp source-cpp">op<span class="br0">(</span><span class="sy2">*</span>first, <span class="sy2">*</span>first<span class="br0">)</span></span></span> （对于 <span class="t-v">(4)</span> ）的结果必须可写入 <code>ForwardIt2</code> 。</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>指向最后被写入元素后一位置的迭代器。</p>
|
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
|
<p>若 <code>first == last</code> ，则此函数无效果并且只会返回 <code>d_first</code> 。</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>
|
|
<p>恰好应用 <code>(last - first) - 1</code> 次二元运算。</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>
|
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<table class="eq-fun-cpp-table">
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<tr>
|
|
<th>版本一</th>
|
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</tr>
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<tr>
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<td>
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|
<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> InputIt, <span class="kw1">class</span> OutputIt<span class="sy1">></span>
|
|
<span class="kw4">constexpr</span> <span class="co1">// C++20 起</span>
|
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OutputIt adjacent_difference<span class="br0">(</span>InputIt first, InputIt last,
|
|
OutputIt d_first<span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw1">if</span> <span class="br0">(</span>first <span class="sy1">==</span> last<span class="br0">)</span> <span class="kw1">return</span> d_first<span class="sy4">;</span>
|
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|
<span class="kw1">typedef</span> <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1"><</span>InputIt<span class="sy1">></span><span class="sy4">::</span><span class="me2">value_type</span> value_t<span class="sy4">;</span>
|
|
value_t acc <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
|
|
<span class="sy2">*</span>d_first <span class="sy1">=</span> acc<span class="sy4">;</span>
|
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<span class="kw1">while</span> <span class="br0">(</span><span class="sy2">++</span>first <span class="sy3">!</span><span class="sy1">=</span> last<span class="br0">)</span> <span class="br0">{</span>
|
|
value_t val <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
|
|
<span class="sy2">*++</span>d_first <span class="sy1">=</span> val <span class="sy2">-</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span><span class="sy4">;</span> <span class="co1">// C++20 起有 std::move</span>
|
|
acc <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>val<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span>
|
|
<span class="kw1">return</span> <span class="sy2">++</span>d_first<span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
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</div>
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</td>
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</tr>
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<tr>
|
|
<th>版本二</th>
|
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</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> InputIt, <span class="kw1">class</span> OutputIt, <span class="kw1">class</span> BinaryOperation<span class="sy1">></span>
|
|
<span class="kw4">constexpr</span> <span class="co1">// C++20 起</span>
|
|
OutputIt adjacent_difference<span class="br0">(</span>InputIt first, InputIt last,
|
|
OutputIt d_first, BinaryOperation op<span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw1">if</span> <span class="br0">(</span>first <span class="sy1">==</span> last<span class="br0">)</span> <span class="kw1">return</span> d_first<span class="sy4">;</span>
|
|
|
|
<span class="kw1">typedef</span> <span class="kw1">typename</span> <a href="cpp-iterator-iterator_traits.html"><span class="kw651">std::<span class="me2">iterator_traits</span></span></a><span class="sy1"><</span>InputIt<span class="sy1">></span><span class="sy4">::</span><span class="me2">value_type</span> value_t<span class="sy4">;</span>
|
|
value_t acc <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
|
|
<span class="sy2">*</span>d_first <span class="sy1">=</span> acc<span class="sy4">;</span>
|
|
<span class="kw1">while</span> <span class="br0">(</span><span class="sy2">++</span>first <span class="sy3">!</span><span class="sy1">=</span> last<span class="br0">)</span> <span class="br0">{</span>
|
|
value_t val <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
|
|
<span class="sy2">*++</span>d_first <span class="sy1">=</span> op<span class="br0">(</span>val, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>acc<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// C++20 起有 std::move</span>
|
|
acc <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>val<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span>
|
|
<span class="kw1">return</span> <span class="sy2">++</span>d_first<span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<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 <numeric></span>
|
|
<span class="co2">#include <vector></span>
|
|
<span class="co2">#include <iostream></span>
|
|
<span class="co2">#include <functional></span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="co1">// 默认实现——二个项之间的差</span>
|
|
|
|
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> v<span class="br0">{</span><span class="nu0">2</span>, <span class="nu0">4</span>, <span class="nu0">6</span>, <span class="nu0">8</span>, <span class="nu0">10</span>, <span class="nu0">12</span>, <span class="nu0">14</span>, <span class="nu0">16</span>, <span class="nu0">18</span>, <span class="nu0">20</span><span class="br0">}</span><span class="sy4">;</span>
|
|
std<span class="sy4">::</span><span class="me2">adjacent_difference</span><span class="br0">(</span>v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, v.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, v.<span class="me1">begin</span><span class="br0">(</span><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> n <span class="sy4">:</span> v<span class="br0">)</span> <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> n <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
|
|
<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> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
|
|
<span class="co1">// 斐波那契</span>
|
|
<span class="co1">// 注意，列表中下一项是当前迭代的结果</span>
|
|
|
|
v <span class="sy1">=</span> <a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span><span class="br0">(</span><span class="nu0">10</span><span class="br0">)</span><span class="sy4">;</span>
|
|
v<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span> <span class="sy1">=</span> <span class="nu0">1</span><span class="sy4">;</span>
|
|
|
|
std<span class="sy4">::</span><span class="me2">adjacent_difference</span><span class="br0">(</span>v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, v.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">-</span> <span class="nu0">1</span>, v.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span> <span class="sy2">+</span> <span class="nu0">1</span>, <a href="cpp-utility-functional-plus.html"><span class="kw1029">std::<span class="me2">plus</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span><span class="br0">(</span><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> n <span class="sy4">:</span> v<span class="br0">)</span> <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> n <span class="sy1"><<</span> <span class="st0">' '</span><span class="sy4">;</span>
|
|
<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> <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">2 2 2 2 2 2 2 2 2 2
|
|
1 1 2 3 5 8 13 21 34 55</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-partial_sum.html"><span class="t-lines"><span>partial_sum</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>计算范围内元素的部分和<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-accumulate.html"><span class="t-lines"><span>accumulate</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>对一个范围内的元素求和<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|