-
Notifications
You must be signed in to change notification settings - Fork 1
Expand file tree
/
Copy pathexpected.html
More file actions
682 lines (619 loc) · 28.5 KB
/
expected.html
File metadata and controls
682 lines (619 loc) · 28.5 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
<!doctype html>
<html class="cpprefjp" lang="ja" itemscope="" itemtype="http://schema.org/WebPage">
<head>
<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-NXNBNVBTJS"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments);}
gtag('js', new Date());
gtag('config', 'G-NXNBNVBTJS');
</script>
<meta charset="UTF-8">
<title>expected - cpprefjp C++日本語リファレンス</title>
<meta name="viewport" content="width=device-width,initial-scale=1">
<meta name="keywords" content="
C++,標準ライブラリ,リファレンス,ドキュメント,STL,std,expected,class template,std,cpp23
">
<meta name="title" content="expected - cpprefjp C++日本語リファレンス" />
<meta itemprop="name" content="expected - cpprefjp C++日本語リファレンス" />
<meta property="og:title" content="expected - cpprefjp C++日本語リファレンス" />
<meta property="og:url" content="https://cpprefjp.github.io/reference/expected/expected.html" />
<meta property="og:site_name" content="cpprefjp - C++日本語リファレンス" />
<meta property="og:type" content="article" />
<meta property="og:description" content="`expected`クラスは、任意の型`T`の値を正常値とし任意の型`E`の値をエラー値として、正常もしくはエラーいずれかの状態を取ることを値として表現できる型である。" />
<meta name="twitter:card" content="summary" />
<meta name="twitter:title" content="expected - cpprefjp C++日本語リファレンス" />
<meta name="twitter:url" content="https://cpprefjp.github.io/reference/expected/expected.html" />
<meta name="twitter:description" content="`expected`クラスは、任意の型`T`の値を正常値とし任意の型`E`の値をエラー値として、正常もしくはエラーいずれかの状態を取ることを値として表現できる型である。" />
<link rel="alternate" type="application/atom+xml" title="Atom" href="https://cpprefjp.github.io/rss.xml" />
<link rel="apple-touch-icon" sizes="180x180" href="../../static/favicons/apple-touch-icon.png?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95">
<link rel="icon" type="image/png" sizes="32x32" href="../../static/favicons/favicon-32x32.png?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95">
<link rel="icon" type="image/png" sizes="16x16" href="../../static/favicons/favicon-16x16.png?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95">
<link rel="manifest" href="../../manifest.json?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95">
<meta name="theme-color" content="#f5f8fc">
<link rel="stylesheet" href="../../static/pygments/default.css?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95">
<!-- <link rel="stylesheet" href="../../static/css/root.css"> -->
<link href="../../static/kunai/css/kunai-stage-0.css?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95" rel="stylesheet">
<link href="../../static/kunai/css/kunai-stage-1.css?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95" rel="stylesheet">
<link href="../../static/kunai/css/kunai-stage-2.css?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95" rel="stylesheet">
<link href="../../static/kunai/css/kunai-stage-3.css?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95" rel="stylesheet">
<script type="text/javascript" src="../../static/kunai/js/kunai-vendor.js?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95"></script>
<script type="text/javascript" src="../../static/kunai/js/kunai.js?cachebust=be86fa2321ebe02b6955b61b98b778e377bcbf95"></script>
<script type="text/javascript">
document.addEventListener('DOMContentLoaded', function() {
var kn = new Kunai;
kn.cpprefjp();
});
</script>
</head>
<body>
<header data-kunai-mdinfo="{"meta": {"header": ["expected"], "id-type": ["class template"], "namespace": ["std"], "cpp": ["cpp23"]}, "sources": [{"id": "3ad69240ee37d80f806ff21967ec6b209c7754ea", "source": "#include <expected>\n#include <iomanip>\n#include <iostream>\n#include <string>\n\n// \u6574\u6570\u9664\u7b97\nstd::expected<int, std::string> idiv(int a, int b)\n{\n if (b == 0) {\n return std::unexpected{\"divide by zero\"};\n }\n if (a % b != 0) {\n return std::unexpected{\"out of domain\"}; \n }\n return a / b;\n}\n\nvoid dump_result(const std::expected<int, std::string>& v)\n{\n if (v) {\n std::cout << *v << std::endl;\n } else {\n std::cout << std::quoted(v.error()) << std::endl; \n }\n}\n\nint main()\n{\n dump_result(idiv(10, 2));\n dump_result(idiv(10, 3));\n dump_result(idiv(10, 0));\n}\n"}], "page_id": ["reference", "expected", "expected"]}">
<nav class="navbar navbar-default" role="navigation">
<div class="container-fluid">
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar-collapse">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="../../index.html">
<div class="title-wrapper clearfix">
<div class="title">cpprefjp - C++日本語リファレンス</div>
</div>
</a>
</div>
<div class="collapse navbar-collapse" id="navbar-collapse">
<ul class="nav navbar-nav navbar-right">
<li>
<div class="google-search">
<script>
(function() {
var cx = '013316413321391058734:ji_u66hl7hq';
var gcse = document.createElement('script');
gcse.type = 'text/javascript';
gcse.async = true;
gcse.src = (document.location.protocol == 'https:' ? 'https:' : 'http:') +
'//www.google.com/cse/cse.js?cx=' + cx;
var s = document.getElementsByTagName('script')[0];
s.parentNode.insertBefore(gcse, s);
})();
</script>
<div class="gcse-search"></div>
</div>
</li>
<li>
<a href="https://github.com/cpprefjp/site">GitHub Project</a>
</li>
</ul>
</div>
</div>
</nav>
</header>
<main id="main" role="main">
<div class="container-fluid">
<div class="row">
<div class="col-sm-9 col-sm-push-3" itemscope itemtype="http://schema.org/Article">
<div class="row">
<div class="col-sm-12 google-search-result">
<gcse:searchresults></gcse:searchresults>
</div>
</div>
<div class="row">
<div class="col-sm-12 content-header">
<ol class="breadcrumb">
<li itemscope itemtype="http://www.schema.org/SiteNavigationElement">
<span>
<a href="../../index.html" itemprop="url">
<i class="fa fa-fw fa-home"></i>
</a>
</span>
</li>
<li itemscope itemtype="http://www.schema.org/SiteNavigationElement">
<span>
<a href="../../reference.html" itemprop="url">
<span itemprop="name">リファレンス</span>
</a>
</span>
</li>
<li itemscope itemtype="http://www.schema.org/SiteNavigationElement">
<span>
<a href="../../reference/expected.html" itemprop="url">
<span itemprop="name">expected</span>
</a>
</span>
</li>
<li class="active" itemscope itemtype="http://www.schema.org/SiteNavigationElement">
<span>
<span itemprop="name">expected</span>
</span>
</li>
</ol>
<div class="crsearch"></div>
</div>
</div>
<div class="row">
<div class="col-sm-12 edit-button">
<p class="text-right"><small>
最終更新日時(UTC):
<span itemprop="datePublished" content="2024-06-11T13:45:38">
2024年06月11日 13時45分38秒
</span>
<br/>
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
<span itemprop="name">Akira Takahashi</span>
</span>
が更新
</small></p>
<p class="text-right">
<a class="history" target="_blank" href="https://github.com/cpprefjp/site/commits/master/reference/expected/expected.md">
<span class="fa fa-fw fa-clock-o fa-flip-horizontal"></span>履歴
</a>
<a class="edit" target="_blank" href="https://github.com/cpprefjp/site/edit/master/reference/expected/expected.md">
<span class="fa fa-fw fa-pencil"></span>編集
</a>
</p>
</div>
</div>
<div class="row">
<div class="col-sm-12 content-body">
<div class="identifier-type">class template</div><div class="header"><expected></div><h1 itemprop="name"><span class="namespace" title="namespace std">std::</span><span class="token">expected</span><span class="cpp cpp23" title="C++23で追加">(C++23)</span></h1>
<div itemprop="articleBody"><p><div class="codehilite"><pre><span></span><code><span class="k">namespace</span><span class="w"> </span><span class="nn">std</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="c1">// プライマリテンプレート</span>
<span class="w"> </span><span class="k">template</span><span class="o"><</span><span class="k">class</span><span class="w"> </span><span class="nc">T</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">E</span><span class="o">></span>
<span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">expected</span><span class="p">;</span>
<span class="w"> </span><span class="c1">// T=cv void 部分特殊化テンプレート</span>
<span class="w"> </span><span class="k">template</span><span class="o"><</span><span class="k">class</span><span class="w"> </span><span class="nc">T</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">E</span><span class="o">></span>
<span class="w"> </span><span class="k">requires</span><span class="w"> </span><span class="n"><a href="../type_traits/is_void.html">is_void_v</a></span><span class="o"><</span><span class="n">T</span><span class="o">></span>
<span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">expected</span><span class="o"><</span><span class="n">T</span><span class="p">,</span><span class="w"> </span><span class="n">E</span><span class="o">></span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h2>概要</h2>
<p><code>expected</code>クラスは、任意の型<code>T</code>の値を正常値とし任意の型<code>E</code>の値をエラー値として、正常もしくはエラーいずれかの状態を取ることを値として表現できる型である。</p>
<p>このクラスは、ヒープからの動的メモリ確保を行わない。
実装は配置newのような機能によって、スタック領域のメモリのみを使用する。</p>
<h2><a class="cpprefjp-defined-word" data-desc="関数等の意味論を構成する要素の1つ。Mandates。満たさなければプログラムが不適格となる要件。この要件は、オーバーロード解決によって選択された関数内での`static_assert`の定数条件式や、関数に対するdelete宣言などで表現できる">適格要件</a></h2>
<ul>
<li>型<code>T</code>および型<code>E</code>は、参照型、関数型、<code><a href="../utility/in_place_t.html">in_place_t</a></code>、<code><a href="unexpect_t.html">unexpect_t</a></code>のいずれでもないこと。</li>
<li>型<code>T</code>は<code><a href="unexpected.html">unexpected</a></code>の特殊化ではないこと。</li>
<li>型<code>T</code>が（<a class="cpprefjp-defined-word" data-desc="型をconstおよび・もしくはvolatileで修飾すること">CV修飾</a>された）<code>void</code>型でなければ、型<code>T</code>はCpp17Destructible要件を満たすこと。</li>
<li>型<code>E</code>は非オブジェクト型、配列型、<code>unexpected</code>の特殊化、<a class="cpprefjp-defined-word" data-desc="型をconstおよび・もしくはvolatileで修飾すること">CV修飾</a>された型のいずれでもないこと。</li>
<li>型<code>E</code>はCpp17Destructible要件を満たすこと。</li>
</ul>
<h2>メンバ関数（プライマリテンプレート）</h2>
<h3>構築・破棄</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected/op_constructor.html">(constructor)</a></code></td>
<td>コンストラクタ</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/op_destructor.html">(destructor)</a></code></td>
<td>デストラクタ</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>代入</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected/op_assign.html">operator=</a></code></td>
<td>代入演算子</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/emplace.html">emplace</a></code></td>
<td>正常値型のコンストラクタ引数から直接構築する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/swap.html">swap</a></code></td>
<td>他の<code>expected</code>オブジェクトとデータを入れ替える</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>値の観測</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected/op_arrow.html">operator-></a></code></td>
<td>正常値へのメンバアクセス</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/op_deref.html">operator*</a></code></td>
<td>正常値への間接参照</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/op_bool.html">operator bool</a></code></td>
<td>正常値を保持しているかを判定する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/has_value.html">has_value</a></code></td>
<td>正常値を保持しているかを判定する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/value.html">value</a></code></td>
<td>正常値を取得する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/error.html">error</a></code></td>
<td>エラー値を取得する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/value_or.html">value_or</a></code></td>
<td>正常値もしくは指定された値を取得する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/error_or.html">error_or</a></code></td>
<td>エラー値もしくは指定された値を取得する</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>モナド操作</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected/and_then.html">and_then</a></code></td>
<td>正常値に対して関数を適用する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/or_else.html">or_else</a></code></td>
<td>エラー値に対して関数を適用する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/transform.html">transform</a></code></td>
<td>正常値を変換する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/transform_error.html">transform_error</a></code></td>
<td>エラー値を変換する</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>比較</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected/op_equal.html">operator==</a></code></td>
<td>等値比較</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected/op_not_equal.html">operator!=</a></code></td>
<td>非等値比較</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h2>メンバ関数（T=cv void 部分特殊化テンプレート）</h2>
<h3>構築・破棄</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected.void/op_constructor.html">(constructor)</a></code></td>
<td>コンストラクタ</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/op_destructor.html">(destructor)</a></code></td>
<td>デストラクタ</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>代入</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected.void/op_assign.html">operator=</a></code></td>
<td>代入演算子</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/emplace.html">emplace</a></code></td>
<td>正常値を保持する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/swap.html">swap</a></code></td>
<td>他の<code>expected</code>オブジェクトとデータを入れ替える</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>値の観測</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected.void/op_deref.html">operator*</a></code></td>
<td>正常値への間接参照</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/op_bool.html">operator bool</a></code></td>
<td>正常値を保持しているかを判定する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/has_value.html">has_value</a></code></td>
<td>正常値を保持しているかを判定する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/value.html">value</a></code></td>
<td>正常値を取得する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/error.html">error</a></code></td>
<td>エラー値を取得する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/error_or.html">error_or</a></code></td>
<td>エラー値もしくは指定された値を取得する</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<p>（<code>expected<cv void, E></code> 部分特殊化では、演算子<a class="cpprefjp-defined-word" data-desc="同名の関数を異なる引数・テンプレート・制約などで複数定義すること。または同名の関数の集合">オーバーロード</a><code>operator-></code>およびメンバ関数<code>value_or</code>は提供されない。）</p>
<h3>モナド操作</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected.void/and_then.html">and_then</a></code></td>
<td>正常値に対して関数を適用する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/or_else.html">or_else</a></code></td>
<td>エラー値に対して関数を適用する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/transform.html">transform</a></code></td>
<td>正常値を変換する</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/transform_error.html">transform_error</a></code></td>
<td>エラー値を変換する</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h3>比較</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected.void/op_equal.html">operator==</a></code></td>
<td>等値比較</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/op_not_equal.html">operator!=</a></code></td>
<td>非等値比較</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h2>メンバ型</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code>value_type</code></td>
<td>正常値の型<code>T</code></td>
<td>C++23</td>
</tr>
<tr>
<td><code>error_type</code></td>
<td>エラー値の型<code>E</code></td>
<td>C++23</td>
</tr>
<tr>
<td><code>unexpected_type</code></td>
<td><code><a href="unexpected.html">unexpected<E></a></code></td>
<td>C++23</td>
</tr>
<tr>
<td><code>template<class U> rebind</code></td>
<td><code>expected<U, error_type></code></td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h2>非メンバ関数</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<thead>
<tr>
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
</tr>
</thead>
<tbody>
<tr>
<td><code><a href="expected/swap_free.html">swap</a></code></td>
<td>2つの<code>expected<T, E></code>オブジェクトを入れ替える</td>
<td>C++23</td>
</tr>
<tr>
<td><code><a href="expected.void/swap_free.html">swap</a></code></td>
<td>2つの<code>expected<cv void, E></code>オブジェクトを入れ替える</td>
<td>C++23</td>
</tr>
</tbody>
</table>
<h2>例</h2>
<p><div class="yata" id="3ad69240ee37d80f806ff21967ec6b209c7754ea"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../expected.html"><expected></a></span>
<span class="cp">#include <a href="../iomanip.html"><iomanip></a></span>
<span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../string.html"><string></a></span>
<span class="c1">// 整数除算</span>
<span class="n"><span style="color:#ff0000">std::expected</span></span><span class="o"><</span><span class="kt">int</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="o">></span><span class="w"> </span><span class="n">idiv</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">a</span><span class="p">,</span><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">b</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">b</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n"><a href="unexpected.html">std::unexpected</a></span><span class="p">{</span><span class="s">"divide by zero"</span><span class="p">};</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">a</span><span class="w"> </span><span class="o">%</span><span class="w"> </span><span class="n">b</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n"><a href="unexpected.html">std::unexpected</a></span><span class="p">{</span><span class="s">"out of domain"</span><span class="p">};</span><span class="w"> </span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="o">/</span><span class="w"> </span><span class="n">b</span><span class="p">;</span>
<span class="p">}</span>
<span class="kt">void</span><span class="w"> </span><span class="n">dump_result</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::expected</span></span><span class="o"><</span><span class="kt">int</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="o">>&</span><span class="w"> </span><span class="n">v</span><span class="p">)</span>
<span class="p">{</span>
<span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">v</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="expected/op_deref.html">*v</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../iomanip/quoted.html">std::quoted</a></span><span class="p">(</span><span class="n"><a href="expected/error.html">v.error()</a></span><span class="p">)</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span><span class="w"> </span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
<span class="kt">int</span><span class="w"> </span><span class="n">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="n">dump_result</span><span class="p">(</span><span class="n">idiv</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">2</span><span class="p">));</span>
<span class="w"> </span><span class="n">dump_result</span><span class="p">(</span><span class="n">idiv</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">3</span><span class="p">));</span>
<span class="w"> </span><span class="n">dump_result</span><span class="p">(</span><span class="n">idiv</span><span class="p">(</span><span class="mi">10</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">));</span>
<span class="p">}</span>
</code></pre></div>
</div></p>
<h3>出力</h3>
<p><pre><code>5
"out of domain"
"divide by zero"
</code></pre></p>
<h2>バージョン</h2>
<h3>言語</h3>
<ul>
<li>C++23</li>
</ul>
<h3>処理系</h3>
<ul>
<li><a href="../../implementation.html#clang">Clang</a>: 16.0 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../implementation.html#gcc">GCC</a>: 12.1 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../implementation.html#icc">ICC</a>: ??</li>
<li><a href="../../implementation.html#visual_cpp">Visual C++</a>: ??</li>
</ul>
<h2>関連項目</h2>
<ul>
<li><code><a href="unexpected.html">unexpected</a></code></li>
<li><code><a href="../optional/optional.html">optional</a></code></li>
</ul>
<h2>参照</h2>
<ul>
<li><a href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p0323r12.html" target="_blank">P0323R12 std::expected</a></li>
<li><a href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2505r5.html" target="_blank">P2505R5 Monadic Functions for <code>std::expected</code></a></li>
</ul></div>
</div>
</div>
</div>
<div id="sidebar" class="col-sm-3 col-sm-pull-9">
</div>
</div>
</div>
</main>
<footer class="footer navbar navbar-default">
<div class="container-fluid">
<p><small>
本サイトの情報は、
<a href="https://creativecommons.org/licenses/by/4.0/deed.ja" rel="nofollow">クリエイティブ・コモンズ 表示 4.0 非移植 ライセンス(CC BY)</a>
の下に提供されています。
</small></p>
</div>
</footer>
</body>
</html>