Skip to content

Commit df18419

Browse files
author
cpprefjp-autoupdate
committed
update automatically
1 parent ff1a9ab commit df18419

File tree

11 files changed

+3424
-1422
lines changed

11 files changed

+3424
-1422
lines changed

‎implementation-status.html

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -164,8 +164,8 @@
164164

165165
<p class="text-right"><small>
166166
最終更新日時(UTC):
167-
<span itemprop="datePublished" content="2024-09-12T03:40:36">
168-
2024年09月12日 03時40分36秒
167+
<span itemprop="datePublished" content="2024-09-12T04:12:48">
168+
2024年09月12日 04時12分48秒
169169
</span>
170170
<br/>
171171
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
@@ -1982,7 +1982,7 @@ <h2><a href="#cpp26" id="cpp26">C++26言語機能の実装状況</a></h2>
19821982
<td></td>
19831983
</tr>
19841984
<tr>
1985-
<td>P0963R3: <span href="https://cpprefjp.github.io/lang/cpp26/structured_binding_declaration_as_a_condition.md.nolink">条件式での構造化束縛の使用を許可</span></td>
1985+
<td>P0963R3: <a href="lang/cpp26/structured_binding_declaration_as_a_condition.html">条件式での構造化束縛の使用を許可</a></td>
19861986
<td>式全体を<code>bool</code>値に変換できる場合に条件式で構造化束縛を使用できることとする</td>
19871987
<td>15</td>
19881988
<td></td>

‎lang/cpp17/selection_statements_with_initializer.html

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -188,8 +188,8 @@
188188

189189
<p class="text-right"><small>
190190
最終更新日時(UTC):
191-
<span itemprop="datePublished" content="2024-07-18T16:39:47">
192-
2024年07月18日 16時39分47秒
191+
<span itemprop="datePublished" content="2024-09-12T04:12:48">
192+
2024年09月12日 04時12分48秒
193193
</span>
194194
<br/>
195195
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
@@ -374,6 +374,7 @@ <h2><a href="#relative-page" id="relative-page">関連項目</a></h2>
374374
<ul>
375375
<li><a href="../cpp20/range-based_for_statements_with_initializer.html">C++20 初期化式をともなう範囲for文</a></li>
376376
<li><a href="../cpp23/extend_init_statement_to_allow_alias_declaration.html">C++23 初期化文での型の別名宣言を許可</a></li>
377+
<li><a href="../cpp26/structured_binding_declaration_as_a_condition.html">C++26 条件式での構造化束縛の使用を許可</a></li>
377378
</ul>
378379
<h2>参照</h2>
379380
<ul>

‎lang/cpp17/structured_bindings.html

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -188,8 +188,8 @@
188188

189189
<p class="text-right"><small>
190190
最終更新日時(UTC):
191-
<span itemprop="datePublished" content="2024-09-12T03:40:36">
192-
2024年09月12日 03時40分36秒
191+
<span itemprop="datePublished" content="2024-09-12T04:12:48">
192+
2024年09月12日 04時12分48秒
193193
</span>
194194
<br/>
195195
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
@@ -518,6 +518,7 @@ <h2><a href="#relative-page" id="relative-page">関連項目</a></h2>
518518
<li><a href="../cpp20/extending_structured_bindings_to_be_more_like_variable_declarations.html">C++20 構造化束縛を拡張して通常の変数宣言のように使用できるようにする</a></li>
519519
<li><a href="../cpp20/reference_capture_of_structured_bindings.html">C++20 構造化束縛した変数の参照キャプチャを許可</a></li>
520520
<li><a href="../cpp26/attributes_for_structured_bindings.html">C++26 構造化束縛への属性を許可</a></li>
521+
<li><a href="../cpp26/structured_binding_declaration_as_a_condition.html">C++26 条件式での構造化束縛の使用を許可</a></li>
521522
</ul>
522523
<h2>参照</h2>
523524
<ul>

‎lang/cpp26.html

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -176,8 +176,8 @@
176176

177177
<p class="text-right"><small>
178178
最終更新日時(UTC):
179-
<span itemprop="datePublished" content="2024-09-12T03:40:36">
180-
2024年09月12日 03時40分36秒
179+
<span itemprop="datePublished" content="2024-09-12T04:12:48">
180+
2024年09月12日 04時12分48秒
181181
</span>
182182
<br/>
183183
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
@@ -273,7 +273,7 @@ <h3>分岐・ループ</h3>
273273
</thead>
274274
<tbody>
275275
<tr>
276-
<td><span href="https://cpprefjp.github.io/lang/cpp26/structured_binding_declaration_as_a_condition.md.nolink">条件式での構造化束縛の使用を許可</span></td>
276+
<td><a href="cpp26/structured_binding_declaration_as_a_condition.html">条件式での構造化束縛の使用を許可</a></td>
277277
<td>式全体を<code>bool</code>値に変換できる場合に条件式で構造化束縛を使用できることとする</td>
278278
</tr>
279279
<tr>

‎lang/cpp26/structured_binding_declaration_as_a_condition.html

Lines changed: 291 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,291 @@
1+
<!doctype html>
2+
<html class="cpprefjp" lang="ja" itemscope="" itemtype="http://schema.org/WebPage">
3+
<head>
4+
5+
6+
<!-- Google tag (gtag.js) -->
7+
<script async src="https://www.googletagmanager.com/gtag/js?id=G-NXNBNVBTJS"></script>
8+
<script>
9+
window.dataLayer = window.dataLayer || [];
10+
function gtag(){dataLayer.push(arguments);}
11+
gtag('js', new Date());
12+
13+
gtag('config', 'G-NXNBNVBTJS');
14+
</script>
15+
16+
17+
<meta charset="UTF-8">
18+
19+
<title>条件式での構造化束縛の使用を許可 [P0963R3] - cpprefjp C++日本語リファレンス</title>
20+
21+
<meta name="viewport" content="width=device-width,initial-scale=1">
22+
<meta name="keywords" content="
23+
C++,標準ライブラリ,リファレンス,ドキュメント,STL,std,cpp26
24+
">
25+
<meta name="title" content="条件式での構造化束縛の使用を許可 [P0963R3] - cpprefjp C++日本語リファレンス" />
26+
<meta itemprop="name" content="条件式での構造化束縛の使用を許可 [P0963R3] - cpprefjp C++日本語リファレンス" />
27+
<meta property="og:title" content="条件式での構造化束縛の使用を許可 [P0963R3] - cpprefjp C++日本語リファレンス" />
28+
<meta property="og:url" content="https://cpprefjp.github.io/lang/cpp26/structured_binding_declaration_as_a_condition.html" />
29+
<meta property="og:site_name" content="cpprefjp - C++日本語リファレンス" />
30+
<meta property="og:type" content="article" />
31+
<meta property="og:description" content="C++26では、`if`文、`while`文、`for`文、`switch`文の条件式において構造化束縛を使用できるようになる。" />
32+
<meta name="twitter:card" content="summary" />
33+
<meta name="twitter:title" content="条件式での構造化束縛の使用を許可 [P0963R3] - cpprefjp C++日本語リファレンス" />
34+
<meta name="twitter:url" content="https://cpprefjp.github.io/lang/cpp26/structured_binding_declaration_as_a_condition.html" />
35+
<meta name="twitter:description" content="C++26では、`if`文、`while`文、`for`文、`switch`文の条件式において構造化束縛を使用できるようになる。" />
36+
37+
38+
<link rel="alternate" type="application/atom+xml" title="Atom" href="https://cpprefjp.github.io/rss.xml" />
39+
40+
41+
<link rel="apple-touch-icon" sizes="180x180" href="../../static/favicons/apple-touch-icon.png?cachebust=0e476399d981581c37613c7023035bba5447c826">
42+
<link rel="icon" type="image/png" sizes="32x32" href="../../static/favicons/favicon-32x32.png?cachebust=0e476399d981581c37613c7023035bba5447c826">
43+
<link rel="icon" type="image/png" sizes="16x16" href="../../static/favicons/favicon-16x16.png?cachebust=0e476399d981581c37613c7023035bba5447c826">
44+
<link rel="manifest" href="../../manifest.json?cachebust=0e476399d981581c37613c7023035bba5447c826">
45+
<meta name="theme-color" content="#f5f8fc">
46+
47+
<link rel="stylesheet" href="../../static/pygments/default.css?cachebust=0e476399d981581c37613c7023035bba5447c826">
48+
<!-- <link rel="stylesheet" href="../../static/css/root.css"> -->
49+
50+
51+
52+
53+
54+
<link href="../../static/kunai/css/kunai-stage-0.css?cachebust=0e476399d981581c37613c7023035bba5447c826" rel="stylesheet">
55+
<link href="../../static/kunai/css/kunai-stage-1.css?cachebust=0e476399d981581c37613c7023035bba5447c826" rel="stylesheet">
56+
<link href="../../static/kunai/css/kunai-stage-2.css?cachebust=0e476399d981581c37613c7023035bba5447c826" rel="stylesheet">
57+
<link href="../../static/kunai/css/kunai-stage-3.css?cachebust=0e476399d981581c37613c7023035bba5447c826" rel="stylesheet">
58+
59+
<script type="text/javascript" src="../../static/kunai/js/kunai-vendor.js?cachebust=0e476399d981581c37613c7023035bba5447c826"></script>
60+
<script type="text/javascript" src="../../static/kunai/js/kunai.js?cachebust=0e476399d981581c37613c7023035bba5447c826"></script>
61+
62+
<script type="text/javascript">
63+
document.addEventListener('DOMContentLoaded', function() {
64+
var kn = new Kunai;
65+
kn.cpprefjp();
66+
});
67+
</script>
68+
69+
</head>
70+
<body>
71+
<header data-kunai-mdinfo="{&#34;meta&#34;: {&#34;cpp&#34;: [&#34;cpp26&#34;]}, &#34;sources&#34;: [], &#34;page_id&#34;: [&#34;lang&#34;, &#34;cpp26&#34;, &#34;structured_binding_declaration_as_a_condition&#34;]}">
72+
<nav class="navbar navbar-default" role="navigation">
73+
<div class="container-fluid">
74+
<div class="navbar-header">
75+
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar-collapse">
76+
<span class="sr-only">Toggle navigation</span>
77+
<span class="icon-bar"></span>
78+
<span class="icon-bar"></span>
79+
<span class="icon-bar"></span>
80+
</button>
81+
<a class="navbar-brand" href="../../index.html">
82+
<div class="title-wrapper clearfix">
83+
<div class="title">cpprefjp - C++日本語リファレンス</div>
84+
</div>
85+
</a>
86+
</div>
87+
88+
<div class="collapse navbar-collapse" id="navbar-collapse">
89+
<ul class="nav navbar-nav navbar-right">
90+
<li>
91+
<div class="google-search">
92+
93+
94+
<script>
95+
(function() {
96+
var cx = '013316413321391058734:ji_u66hl7hq';
97+
var gcse = document.createElement('script');
98+
gcse.type = 'text/javascript';
99+
gcse.async = true;
100+
gcse.src = (document.location.protocol == 'https:' ? 'https:' : 'http:') +
101+
'//www.google.com/cse/cse.js?cx=' + cx;
102+
var s = document.getElementsByTagName('script')[0];
103+
s.parentNode.insertBefore(gcse, s);
104+
})();
105+
</script>
106+
<div class="gcse-search"></div>
107+
108+
109+
</div>
110+
</li>
111+
<li>
112+
<a href="https://github.com/cpprefjp/site">GitHub Project</a>
113+
</li>
114+
</ul>
115+
</div>
116+
</div>
117+
</nav>
118+
</header>
119+
120+
<main id="main" role="main">
121+
<div class="container-fluid">
122+
<div class="row">
123+
<div class="col-sm-9 col-sm-push-3" itemscope itemtype="http://schema.org/Article">
124+
<div class="row">
125+
<div class="col-sm-12 google-search-result">
126+
<gcse:searchresults></gcse:searchresults>
127+
</div>
128+
</div>
129+
<div class="row">
130+
<div class="col-sm-12 content-header">
131+
132+
<ol class="breadcrumb">
133+
134+
<li itemscope itemtype="http://www.schema.org/SiteNavigationElement">
135+
<span>
136+
137+
<a href="../../index.html" itemprop="url">
138+
139+
<i class="fa fa-fw fa-home"></i>
140+
141+
</a>
142+
143+
</span>
144+
</li>
145+
146+
<li itemscope itemtype="http://www.schema.org/SiteNavigationElement">
147+
<span>
148+
149+
<a href="../../lang.html" itemprop="url">
150+
151+
<span itemprop="name">言語機能</span>
152+
153+
</a>
154+
155+
</span>
156+
</li>
157+
158+
<li itemscope itemtype="http://www.schema.org/SiteNavigationElement">
159+
<span>
160+
161+
<a href="../../lang/cpp26.html" itemprop="url">
162+
163+
<span itemprop="name">C++26</span>
164+
165+
</a>
166+
167+
</span>
168+
</li>
169+
170+
<li class="active" itemscope itemtype="http://www.schema.org/SiteNavigationElement">
171+
<span>
172+
173+
174+
<span itemprop="name">条件式での構造化束縛の使用を許可 [P0963R3]</span>
175+
176+
177+
</span>
178+
</li>
179+
180+
</ol>
181+
<div class="crsearch"></div>
182+
183+
</div>
184+
</div>
185+
<div class="row">
186+
<div class="col-sm-12 edit-button">
187+
188+
189+
<p class="text-right"><small>
190+
最終更新日時(UTC):
191+
<span itemprop="datePublished" content="2024-09-12T04:14:47">
192+
2024年09月12日 04時14分47秒
193+
</span>
194+
<br/>
195+
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
196+
<span itemprop="name">Akira Takahashi</span>
197+
</span>
198+
が更新
199+
</small></p>
200+
201+
202+
<p class="text-right">
203+
<a class="history" target="_blank" href="https://github.com/cpprefjp/site/commits/master/lang/cpp26/structured_binding_declaration_as_a_condition.md">
204+
<span class="fa fa-fw fa-clock-o fa-flip-horizontal"></span>履歴
205+
</a>
206+
<a class="edit" target="_blank" href="https://github.com/cpprefjp/site/edit/master/lang/cpp26/structured_binding_declaration_as_a_condition.md">
207+
<span class="fa fa-fw fa-pencil"></span>編集
208+
</a>
209+
</p>
210+
</div>
211+
</div>
212+
<div class="row">
213+
<div class="col-sm-12 content-body">
214+
215+
<h1 itemprop="name"><span class="token">条件式での構造化束縛の使用を許可 [P0963R3]</span><span class="cpp cpp26" title="C++26で追加">(C++26)</span></h1>
216+
<div itemprop="articleBody"><p></p>
217+
<p>このページはC++26に採用される見込みの言語機能の変更を解説しています。</p>
218+
<p>のちのC++規格でさらに変更される場合があるため<a href="#relative-page">関連項目</a>を参照してください。</p>
219+
<p></p>
220+
<h2>概要</h2>
221+
<p>C++26では、<code>if</code>文、<code>while</code>文、<code>for</code>文、<code>switch</code>文の条件式において構造化束縛を使用できるようになる。</p>
222+
<p>C++23までは、条件分岐文の初期化式で構造化束縛は使用できたが、その場合に条件式を別途指定する必要があった。C++26では構造化束縛した全体が<code>bool</code>型に変換可能であれば、条件式として構造化束縛を使用できるようになった。</p>
223+
<p><pre><code>// C++23
224+
if (auto [to, ec] = <a href="../../reference/charconv/to_chars.html">std::to_chars</a>(p, last, 42); ec == <a href="../../reference/system_error/errc.html">std::errc</a>{}) {
225+
auto s = <a href="../../reference/string/basic_string.html">std::string</a>(p, to);
226+
…
227+
}
228+
229+
// C++26
230+
// <a href="../../reference/charconv/to_chars.html">std::to_chars</a>の戻り値型である<a href="../../reference/charconv/to_chars_result.html">std::to_chars_result</a>は、
231+
// boolへの変換演算子をもつ
232+
if (auto [to, ec] = <a href="../../reference/charconv/to_chars.html">std::to_chars</a>(p, last, 42)) {
233+
auto s = <a href="../../reference/string/basic_string.html">std::string</a>(p, to);
234+
…
235+
}
236+
</code></pre></p>
237+
<p>なお、条件分岐文での初期化式と、全体を<code>bool</code>変換する条件式は別で指定できる。</p>
238+
<p><div class="codehilite"><pre><span></span><code><span class="cp">#include</span> <span class="cpf"><a href="../../reference/print.html">&lt;print&gt;</a></span><span class="cp"></span>
239+
<span class="cp">#include</span> <span class="cpf"><a href="../../reference/charconv.html">&lt;charconv&gt;</a></span><span class="cp"></span>
240+
<span class="cp">#include</span> <span class="cpf"><a href="../../reference/string_view.html">&lt;string_view&gt;</a></span><span class="cp"></span>
241+
242+
<span class="kt">int</span> <span class="nf">f</span><span class="p">()</span> <span class="p">{</span> <span class="k">return</span> <span class="mi">123</span><span class="p">;</span> <span class="p">}</span>
243+
244+
<span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
245+
<span class="p">{</span>
246+
<span class="kt">char</span> <span class="n">out</span><span class="p">[</span><span class="mi">50</span><span class="p">]{};</span>
247+
<span class="k">auto</span> <span class="n">begin</span> <span class="o">=</span> <span class="n"><a href="../../reference/iterator/begin.html">std::begin</a></span><span class="p">(</span><span class="n">out</span><span class="p">);</span>
248+
<span class="k">auto</span> <span class="n">end</span> <span class="o">=</span> <span class="n"><a href="../../reference/iterator/end.html">std::end</a></span><span class="p">(</span><span class="n">out</span><span class="p">);</span>
249+
250+
<span class="k">if</span> <span class="p">(</span><span class="kt">int</span> <span class="n">value</span> <span class="o">=</span> <span class="n">f</span><span class="p">();</span> <span class="k">auto</span> <span class="p">[</span><span class="n">ptr</span><span class="p">,</span> <span class="n">ec</span><span class="p">]</span> <span class="o">=</span> <span class="n"><a href="../../reference/charconv/to_chars.html">std::to_chars</a></span><span class="p">(</span><span class="n">begin</span><span class="p">,</span> <span class="n">end</span><span class="p">,</span> <span class="n">value</span><span class="p">))</span> <span class="p">{</span>
251+
<span class="n"><a href="../../reference/print/println.html">std::println</a></span><span class="p">(</span><span class="s">"{}"</span><span class="p">,</span> <span class="n"><a href="../../reference/string_view/basic_string_view.html">std::string_view</a></span><span class="p">(</span><span class="n">begin</span><span class="p">,</span> <span class="n">ptr</span> <span class="o">-</span> <span class="n">begin</span><span class="p">));</span>
252+
<span class="p">}</span>
253+
<span class="k">else</span> <span class="p">{</span>
254+
<span class="n"><a href="../../reference/print/println.html">std::println</a></span><span class="p">(</span><span class="s">"conversion failed."</span><span class="p">);</span>
255+
<span class="p">}</span>
256+
<span class="p">}</span>
257+
</code></pre></div>
258+
</p>
259+
<h2><a href="#relative-page" id="relative-page">関連項目</a></h2>
260+
<ul>
261+
<li><a href="../cpp17/structured_bindings.html">C++17 構造化束縛</a></li>
262+
<li><a href="../cpp17/selection_statements_with_initializer.html">C++17 <code>if</code>文と<code>switch</code>文の条件式と初期化を分離</a></li>
263+
</ul>
264+
<h2>参照</h2>
265+
<ul>
266+
<li><a href="https://open-std.org/jtc1/sc22/wg21/docs/papers/2024/p0963r3.html" target="_blank">P0963R3 Structured binding declaration as a condition</a></li>
267+
</ul></div>
268+
269+
</div>
270+
</div>
271+
</div>
272+
273+
274+
<div id="sidebar" class="col-sm-3 col-sm-pull-9">
275+
</div>
276+
277+
278+
</div>
279+
</div>
280+
</main>
281+
<footer class="footer navbar navbar-default">
282+
<div class="container-fluid">
283+
<p><small>
284+
本サイトの情報は、
285+
<a href="https://creativecommons.org/licenses/by/3.0/deed.ja" rel="nofollow">クリエイティブ・コモンズ 表示 3.0 非移植 ライセンス(CC BY)</a>
286+
の下に提供されています。
287+
</small></p>
288+
</div>
289+
</footer>
290+
</body>
291+
</html>

0 commit comments

Comments
 (0)