上传cppreference
This commit is contained in:
148
web/cppreference-zh/chmhelp/cpp-ranges-take_view-begin.html
Normal file
148
web/cppreference-zh/chmhelp/cpp-ranges-take_view-begin.html
Normal file
@@ -0,0 +1,148 @@
|
||||
<!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::ranges::take_view<V>::begin</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_ranges_take_view_begin 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::ranges::take_view<V>::</span>begin</h1>
|
||||
<div id="bodyContent">
|
||||
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-ranges.html">ranges</a>‎ | <a href="cpp-ranges-take_view.html">take view</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-dcl t-since-cxx20">
|
||||
<td>
|
||||
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="kw4">auto</span> begin<span class="br0">(</span><span class="br0">)</span> requires <span class="br0">(</span><span class="sy3">!</span>__SimpleView<span class="sy1"><</span>V<span class="sy1">></span><span class="br0">)</span><span class="sy4">;</span></span></div>
|
||||
</td>
|
||||
<td>(1)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl t-since-cxx20">
|
||||
<td>
|
||||
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="kw4">auto</span> begin<span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span> requires ranges<span class="sy4">::</span><span class="me2">range</span><span class="sy1"><</span><span class="kw4">const</span> V<span class="sy1">></span><span class="sy4">;</span></span></div>
|
||||
</td>
|
||||
<td>(2)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl-sep">
|
||||
<td></td>
|
||||
<td></td>
|
||||
<td></td>
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<p>返回指向 <code>take_view</code> 首元素的迭代器。</p>
|
||||
<div class="t-li1"><span class="t-li">1)</span> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">counted_iterator</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">range_iterator_t</span><span class="sy1"><</span>V<span class="sy1">></span></span></span> 。</div>
|
||||
<div class="t-li1"><span class="t-li">2)</span> 返回 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">counted_iterator</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">range_iterator_t</span><span class="sy1"><</span><span class="kw4">const</span> V<span class="sy1">></span></span></span> 。</div>
|
||||
<p>重载 <span class="t-v">(1)</span> 仅若 <code>V</code> 是<a href="cpp-ranges.html#.E8.BE.85.E5.8A.A9.E6.A6.82.E5.BF.B5">简单视图</a>（即若 <code>V</code> 与 <code>const V</code> 均为视图且拥有相同迭代器与哨位类型）才参与重载决议。</p>
|
||||
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
||||
<p>（无）</p>
|
||||
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
||||
<p>结果依赖于可能为 const 限定的底层视图类型 <code>_Base</code> ，即 <span class="t-c"><span class="mw-geshi cpp source-cpp">V</span></span> （对于重载 <span class="t-v">(1)</span> ）或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">const</span> V</span></span> （对于重载 <span class="t-v">(2)</span> ）所满足的概念。</p>
|
||||
<p>令 <code>base_</code> 为底层视图， <code>count_</code> 为传递给构造函数的数（若默认初始化则为 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> ）。</p>
|
||||
<table class="wikitable">
|
||||
<tr>
|
||||
<th rowspan="2" colspan="2">底层视图满足……</th>
|
||||
<th colspan="2"><a href="cpp-ranges-random_access_range.html"><code>random_access_range</code></a></th>
|
||||
</tr>
|
||||
<tr>
|
||||
<th>是</th>
|
||||
<th>否</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<th rowspan="2"><a href="cpp-ranges-sized_range.html"><code>sized_range</code></a></th>
|
||||
<th>是</th>
|
||||
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>base_<span class="br0">)</span></span></span></td>
|
||||
<td><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">counted_iterator</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>base_<span class="br0">)</span>,<br /></span></span>
|
||||
<p>ranges<span class="sy4">::</span><span class="me2">range_difference_t</span><span class="sy1"><</span>Base_<span class="sy1">></span><span class="br0">(</span>this<span class="sy2">-</span><span class="sy1">></span>size<span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="br0">)</span></p>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<th>否</th>
|
||||
<td colspan="2"><span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">counted_iterator</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>base_<span class="br0">)</span>, count_<span class="br0">)</span></span></span></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 <ranges></span>
|
||||
<span class="co2">#include <iostream></span>
|
||||
<span class="co2">#include <string_view></span>
|
||||
<span class="kw1">using</span> <span class="kw1">namespace</span> std<span class="sy4">::</span><span class="me2">literals</span><span class="sy4">;</span>
|
||||
|
||||
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
||||
<span class="br0">{</span>
|
||||
<span class="kw4">static</span> <span class="kw4">constexpr</span> <span class="kw4">auto</span> sv <span class="sy1">=</span> <span class="br0">{</span><span class="st0">"∀x"</span>sv, <span class="st0">"∃y"</span>sv, <span class="st0">"ε"</span>sv, <span class="st0">"δ"</span>sv<span class="br0">}</span><span class="sy4">;</span>
|
||||
|
||||
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="sy2">*</span>std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">take_view</span><span class="br0">(</span>sv, <span class="nu0">8</span><span class="br0">)</span>.<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>
|
||||
<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">∀x</pre></div>
|
||||
</div>
|
||||
</div>
|
||||
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
|
||||
<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
|
||||
<table class="dsctable" style="font-size:0.8em">
|
||||
<tr>
|
||||
<th>DR</th>
|
||||
<th>应用于</th>
|
||||
<th>出版时的行为</th>
|
||||
<th>正确行为</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td><a rel="nofollow" class="external text" href="https://wg21.link/P2393R1">P2393R1</a></td>
|
||||
<td>C++20</td>
|
||||
<td>有符号与无符号整数类间的隐式转换可能失败</td>
|
||||
<td>使之为显式</td>
|
||||
</tr>
|
||||
</table>
|
||||
<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-ranges-take_view-end.html"><span class="t-lines"><span>end</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>返回指向末尾的迭代器或哨位<br />
|
||||
<span class="t-mark">(公开成员函数)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-iterator-counted_iterator.html"><span class="t-lines"><span>counted_iterator</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>对到范围结尾距离进行跟踪的迭代器适配器<br />
|
||||
<span class="t-mark">(类模板)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-ranges-take_view-sentinel-operator_cmp.html"><span class="t-lines"><span>operator==</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>比较哨位与从 <strong class="selflink"><tt>take_view::begin</tt></strong> 返回的迭代器<br />
|
||||
<span class="t-mark">(函数)</span></td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
<div class="visualClear"></div>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Reference in New Issue
Block a user