上传cppreference
This commit is contained in:
@@ -0,0 +1,164 @@
|
||||
<!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>operator==,!=,<,<=,>,>=,<=>(std::basic_string_view)</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_string_basic_string_view_operator_cmp skin-cppreference2 action-view cpp-navbar">
|
||||
<div id="cpp-content-base">
|
||||
<div id="content"><a id="top"></a>
|
||||
<h1 id="firstHeading" class="firstHeading">operator==,!=,<,<=,>,>=,<=><small>(std::basic_string_view)</small></h1>
|
||||
<div id="bodyContent">
|
||||
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-string.html">string</a>‎ | <a href="cpp-string-basic_string_view.html">basic string 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-dsc-header">
|
||||
<td>
|
||||
<div>定义于头文件 <code><a href="cpp-header-string_view.html"><string_view></a></code></div>
|
||||
</td>
|
||||
<td></td>
|
||||
<td></td>
|
||||
</tr>
|
||||
<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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(1)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl t-since-cxx17 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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy3">!</span><span class="sy1">=</span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(2)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
|
||||
<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl t-since-cxx17 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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1"><</span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(3)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
|
||||
<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl t-since-cxx17 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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1"><=</span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(4)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
|
||||
<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl t-since-cxx17 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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">></span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(5)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span><br />
|
||||
<span class="t-mark-rev t-until-cxx20">(C++20 前)</span></td>
|
||||
</tr>
|
||||
<tr class="t-dcl t-since-cxx17 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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">>=</span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(6)</td>
|
||||
<td><span class="t-mark-rev t-since-cxx17">(C++17 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> CharT, <span class="kw1">class</span> Traits <span class="sy1">></span><br /></span>
|
||||
<p><span class="kw4">constexpr</span> <span class="coMULTI">/*comp-cat*/</span><br />
|
||||
operator<span class="sy1"><=></span><span class="br0">(</span> <a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> lhs,<br /></p>
|
||||
<a href="cpp-string-basic_string_view.html"><span class="kw1246">std::<span class="me2">basic_string_view</span></span></a><span class="sy1"><</span>CharT,Traits<span class="sy1">></span> rhs <span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span></div>
|
||||
</td>
|
||||
<td>(7)</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>比较二个视图。</p>
|
||||
<p>通过 <span class="t-lc"><a href="cpp-string-basic_string_view-compare.html">compare()</a></span> 成员函数进行所有比较（其自身以 <code>Traits::compare()</code> 定义）：</p>
|
||||
<ul>
|
||||
<li>若 <code>lhs</code> 与 <code>rhs</code> 的大小相等且 <code>lhs</code> 中每个字符等于 <code>rhs</code> 在同一位置的字符，则二个视图相等。</li>
|
||||
</ul>
|
||||
<ul>
|
||||
<li>比较顺序按字典序进行——由等价于 <span class="t-lc"><a href="cpp-algorithm-lexicographical_compare.html">std::lexicographical_compare</a></span> 的函数进行比较。</li>
|
||||
</ul>
|
||||
<table class="t-rev-begin">
|
||||
<tr class="t-rev t-since-cxx20">
|
||||
<td>
|
||||
<p>三路比较运算符的返回类型（ <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*comp-cat*/</span></span></span> ）为 <span class="t-c"><span class="mw-geshi cpp source-cpp">Traits<span class="sy4">::</span><span class="me2">comparison_category</span></span></span> ，若该有限定标识合法并指代类型，否则为 <span class="t-lc">std::weak_ordering</span> 。若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*comp-cat*/</span></span></span> 不是比较类别类型，则程序非良构。</p>
|
||||
<p><code><</code>、 <code><=</code>、 <code>></code>、 <code>>=</code> 及 <code>!=</code> 运算符分别从 <code>operator<=></code> 与 <code>operator==</code> <a href="cpp-language-operators.html#.E5.85.B3.E7.B3.BB.E8.BF.90.E7.AE.97.E7.AC.A6">合成</a>。</p>
|
||||
</td>
|
||||
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
||||
</tr>
|
||||
</table>
|
||||
<p>实现应对这些函数提供充足的额外 <code>constexpr</code> 及 <code>noexcept</code> 重载，以令 <code>basic_string_view<CharT,Traits></code> 对象 <code>sv</code> 可以与另一带隐式转换成 <code>basic_string_view<CharT,Traits></code> 的对象 <code>t</code> 比较，而且语义上与比较 <code>sv</code> 和 <code>basic_string_view<CharT,Traits>(t)</code> 相同。</p>
|
||||
<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>lhs, rhs</td>
|
||||
<td>-</td>
|
||||
<td>要比较的视图</td>
|
||||
</tr>
|
||||
</table>
|
||||
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
||||
<div class="t-li1"><span class="t-li">1-6)</span> 若对应比较关系成立则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 。</div>
|
||||
<div class="t-li1"><span class="t-li">7)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">static_cast</span><span class="sy1"><</span><span class="coMULTI">/*comp-cat*/</span><span class="sy1">></span><span class="br0">(</span>lhs.<span class="me1">compare</span><span class="br0">(</span>rhs<span class="br0">)</span> <span class="sy1"><=></span> <span class="nu0">0</span><span class="br0">)</span></span></span> 。</div>
|
||||
<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
|
||||
<p>与视图大小成线性。</p>
|
||||
<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
|
||||
<p>充足的额外重载可通过一个参数类型中的非推导语境实现。</p>
|
||||
<table class="t-rev-begin">
|
||||
<tr class="t-rev t-since-cxx20">
|
||||
<td>
|
||||
<p><span class="t-lc"><a href="cpp-string-basic_string_view.html">std::string_view</a></span> 、 <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::wstring_view</a></span> 、 <span class="t-lc">std::u8string_view</span> 、 <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::u16string_view</a></span> 与 <span class="t-lc"><a href="cpp-string-basic_string_view.html">std::u32string_view</a></span> 的三路比较结果类型为 <span class="t-lc">std::strong_ordering</span> 。</p>
|
||||
</td>
|
||||
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
||||
</tr>
|
||||
</table>
|
||||
<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://cplusplus.github.io/LWG/issue3432">LWG 3432</a></td>
|
||||
<td>C++20</td>
|
||||
<td>未要求 <code>operator<=></code> 的返回类型为比较类别类型</td>
|
||||
<td>已要求</td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
<div class="visualClear"></div>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Reference in New Issue
Block a user