-
Notifications
You must be signed in to change notification settings - Fork 1
Expand file tree
/
Copy pathchar_traits.html
More file actions
699 lines (625 loc) · 43.4 KB
/
char_traits.html
File metadata and controls
699 lines (625 loc) · 43.4 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
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
<!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>char_traits - 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,string,std,class template
">
<meta name="title" content="char_traits - cpprefjp C++日本語リファレンス" />
<meta itemprop="name" content="char_traits - cpprefjp C++日本語リファレンス" />
<meta property="og:title" content="char_traits - cpprefjp C++日本語リファレンス" />
<meta property="og:url" content="https://cpprefjp.github.io/reference/string/char_traits.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="`char_traits`は、[`basic_string`](basic_string.md)文字列クラスのおける、各要素の特性を使用するためのクラスである。 " />
<meta name="twitter:card" content="summary" />
<meta name="twitter:title" content="char_traits - cpprefjp C++日本語リファレンス" />
<meta name="twitter:url" content="https://cpprefjp.github.io/reference/string/char_traits.html" />
<meta name="twitter:description" content="`char_traits`は、[`basic_string`](basic_string.md)文字列クラスのおける、各要素の特性を使用するためのクラスである。 " />
<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": ["string"], "namespace": ["std"], "id-type": ["class template"]}, "sources": [{"id": "1af702e60c8463ac15f58c3f80ae5fcee1764a07", "source": "#include <iostream>\n#include <string>\n\nint main()\n{\n // std::string\u3068\u540c\u3058\n std::basic_string<char, std::char_traits<char>> a = \"aaa\";\n std::basic_string<char, std::char_traits<char>> b = \"bbb\";\n\n // char_traits::compare()\u3067\u6bd4\u8f03\u304c\u884c\u308f\u308c\u308b\n if (a < b) {\n std::cout << \"then\" << std::endl;\n }\n else {\n std::cout << \"else\" << std::endl;\n }\n}\n"}, {"id": "da9b7f9fe5233935f1dcd0f4b2d63c684349d05f", "source": "#include <string>\n#include <compare>\n#include <cctype>\n#include <algorithm>\n\ntemplate <class T>\nclass case_insensitive_char_traits {\n using base_traits = std::char_traits<T>;\npublic:\n using char_type = char;\n using int_type = int;\n using off_type = std::streamoff;\n using pos_type = std::streampos;\n using state_type = std::mbstate_t;\n using comparison_category = std::weak_ordering;\n\n static constexpr void assign(char_type& c1, const char_type& c2) noexcept {\n base_traits::assign(c1, c2);\n }\n\n static constexpr bool eq(char_type c1, char_type c2) noexcept {\n return base_traits::eq(std::tolower(c1), std::tolower(c2));\n }\n\n static constexpr bool lt(char_type c1, char_type c2) noexcept {\n return base_traits::lt(std::tolower(c1), std::tolower(c2));\n }\n\n static constexpr int compare(const char_type* s1, const char_type* s2, size_t n) {\n auto order = std::lexicographical_compare_three_way(s1, s1 + n, s2, s2 + n,\n [](char_type c1, char_type c2) -> std::weak_ordering {\n return std::tolower(c1) <=> std::tolower(c2);\n });\n return order == std::weak_ordering::equivalent ? 0 :\n order == std::weak_ordering::greater ? 1 :\n -1;\n }\n\n static constexpr size_t length(const char_type* s) {\n return base_traits::length(s);\n }\n\n static constexpr const char_type* find(const char_type* s, size_t n,\n const char_type& a) {\n return std::find_if(s, s + n, [a](char_type c) {\n return std::tolower(c) == a;\n });\n }\n\n static constexpr char_type* move(char_type* s1, const char_type* s2, size_t n) {\n return base_traits::move(s1, s2, n);\n }\n\n static constexpr char_type* copy(char_type* s1, const char_type* s2, size_t n) {\n return base_traits::copy(s1, s2, n);\n }\n\n static constexpr char_type* assign(char_type* s, size_t n, char_type a) {\n return base_traits::assign(s, n, a);\n }\n};\n\n#include <iostream>\nint main() {\n using case_insensitive_string =\n std::basic_string<char, case_insensitive_char_traits<char>>;\n case_insensitive_string a = \"AbC\";\n case_insensitive_string b = \"aBc\";\n\n if (a == b) {\n std::cout << \"equal\" << std::endl;\n }\n else {\n std::cout << \"not equal\" << std::endl;\n }\n}\n"}], "page_id": ["reference", "string", "char_traits"]}">
<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/string.html" itemprop="url">
<span itemprop="name">string</span>
</a>
</span>
</li>
<li class="active" itemscope itemtype="http://www.schema.org/SiteNavigationElement">
<span>
<span itemprop="name">char_traits</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="2025-07-08T15:33:39">
2025年07月08日 15時33分39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/string/char_traits.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/string/char_traits.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"><string></div><h1 itemprop="name"><span class="namespace" title="namespace std">std::</span><span class="token">char_traits</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="k">template</span><span class="o"><</span><span class="k">class</span><span class="w"> </span><span class="nc">charT</span><span class="o">></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">char_traits</span><span class="p">;</span>
<span class="w"> </span><span class="k">template</span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">char_traits</span><span class="o"><</span><span class="kt">char</span><span class="o">></span><span class="p">;</span>
<span class="w"> </span><span class="k">template</span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">char_traits</span><span class="o"><</span><span class="kt">char8_t</span><span class="o">></span><span class="p">;</span><span class="w"> </span><span class="c1">// C++20から</span>
<span class="w"> </span><span class="k">template</span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">char_traits</span><span class="o"><</span><span class="kt">char16_t</span><span class="o">></span><span class="p">;</span><span class="w"> </span><span class="c1">// C++11から</span>
<span class="w"> </span><span class="k">template</span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">char_traits</span><span class="o"><</span><span class="kt">char32_t</span><span class="o">></span><span class="p">;</span><span class="w"> </span><span class="c1">// C++11から</span>
<span class="w"> </span><span class="k">template</span><span class="o"><></span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="nc">char_traits</span><span class="o"><</span><span class="kt">wchar_t</span><span class="o">></span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h2>概要</h2>
<p><code>char_traits</code>は、<code><a href="basic_string.html">basic_string</a></code>文字列クラスのおける、各要素の特性を使用するためのクラスである。<br />
このクラスと同じインタフェースのクラスを用意して<code><a href="basic_string.html">basic_string</a></code>クラスのテンプレート引数として指定することにより、ユーザー独自の処理に切り替えることが可能である。たとえば、大文字・小文字を区別しない比較のためのカスタマイズに利用できる。</p>
<p>テンプレートパラメータは以下を意味する：</p>
<ul>
<li><code>charT</code> : <code>basic_string</code>クラスが扱う文字型</li>
</ul>
<h2>静的メンバ関数</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="char_traits/assign.html">assign</a></code></td>
<td>代入</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/eq.html">eq</a></code></td>
<td>等値比較</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/lt.html">lt</a></code></td>
<td>小なり比較</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/compare.html">compare</a></code></td>
<td>比較</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/length.html">length</a></code></td>
<td>文字列長を取得する</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/find.html">find</a></code></td>
<td>文字列中から特定の値を検索する</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/move.html">move</a></code></td>
<td>文字列を他のシーケンスにコピーする</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/copy.html">copy</a></code></td>
<td>文字列を他のシーケンスにコピーする</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/not_eof.html">not_eof</a></code></td>
<td>文字がファイル終端文字(EOF)ではないかを判定する</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/to_char_type.html">to_char_type</a></code></td>
<td>数値を文字に変換する</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/to_int_type.html">to_int_type</a></code></td>
<td>文字を数値に変換する</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/eq_int_type.html">eq_int_type</a></code></td>
<td>数値の等値比較</td>
<td></td>
</tr>
<tr>
<td><code><a href="char_traits/eof.html">eof</a></code></td>
<td>ファイル終端文字(EOF)を表す数値を取得する</td>
<td></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>char_type</code></td>
<td>文字コンテナの実装で使用される文字型</td>
<td></td>
</tr>
<tr>
<td><code>int_type</code></td>
<td>文字に対応する値を表す数値型</td>
<td></td>
</tr>
<tr>
<td><code>off_type</code></td>
<td>文字の差を表す型</td>
<td></td>
</tr>
<tr>
<td><code>pos_type</code></td>
<td>位置を表す型</td>
<td></td>
</tr>
<tr>
<td><code>state_type</code></td>
<td>ストリームのマルチバイト文字の変換の状態を表す型</td>
<td></td>
</tr>
<tr>
<td><code>comparison_category</code></td>
<td>比較カテゴリ</td>
<td>C++20</td>
</tr>
</tbody>
</table>
<h3>charによる特殊化のメンバ型定義</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>char_type</code></td>
<td><code>char</code></td>
<td></td>
</tr>
<tr>
<td><code>int_type</code></td>
<td><code>int</code></td>
<td></td>
</tr>
<tr>
<td><code>off_type</code></td>
<td><code>streamoff</code></td>
<td></td>
</tr>
<tr>
<td><code>pos_type</code></td>
<td><code>streampos</code></td>
<td></td>
</tr>
<tr>
<td><code>state_type</code></td>
<td><code>mbstate_t</code></td>
<td></td>
</tr>
<tr>
<td><code>comparison_category</code></td>
<td><code><a href="../compare/strong_ordering.html">strong_ordering</a></code></td>
<td>C++20</td>
</tr>
</tbody>
</table>
<h3>char8_tによる特殊化のメンバ型定義 (C++20)</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>char_type</code></td>
<td><code>char8_t</code></td>
<td>C++20</td>
</tr>
<tr>
<td><code>int_type</code></td>
<td><code>unsigned int</code></td>
<td>C++20</td>
</tr>
<tr>
<td><code>off_type</code></td>
<td><code>streamoff</code></td>
<td>C++20</td>
</tr>
<tr>
<td><code>pos_type</code></td>
<td><code>u8streampos</code></td>
<td>C++20</td>
</tr>
<tr>
<td><code>state_type</code></td>
<td><code>mbstate_t</code></td>
<td>C++20</td>
</tr>
<tr>
<td><code>comparison_category</code></td>
<td><code><a href="../compare/strong_ordering.html">strong_ordering</a></code></td>
<td>C++20</td>
</tr>
</tbody>
</table>
<h3>char16_tによる特殊化のメンバ型定義 (C++11)</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>char_type</code></td>
<td><code>char16_t</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>int_type</code></td>
<td><code>uint_least16_t</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>off_type</code></td>
<td><code>streamoff</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>pos_type</code></td>
<td><code>u16streampos</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>state_type</code></td>
<td><code>mbstate_t</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>comparison_category</code></td>
<td><code><a href="../compare/strong_ordering.html">strong_ordering</a></code></td>
<td>C++20</td>
</tr>
</tbody>
</table>
<h3>char32_tによる特殊化のメンバ型定義 (C++11)</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>char_type</code></td>
<td><code>char32_t</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>int_type</code></td>
<td><code>uint_least32_t</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>off_type</code></td>
<td><code>streamoff</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>pos_type</code></td>
<td><code>u32streampos</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>state_type</code></td>
<td><code>mbstate_t</code></td>
<td>C++11</td>
</tr>
<tr>
<td><code>comparison_category</code></td>
<td><code><a href="../compare/strong_ordering.html">strong_ordering</a></code></td>
<td>C++20</td>
</tr>
</tbody>
</table>
<h3>wchar_tによる特殊化のメンバ型定義</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>char_type</code></td>
<td><code>wchar_t</code></td>
<td></td>
</tr>
<tr>
<td><code>int_type</code></td>
<td><code>wint_t</code></td>
<td></td>
</tr>
<tr>
<td><code>off_type</code></td>
<td><code>streamoff</code></td>
<td></td>
</tr>
<tr>
<td><code>pos_type</code></td>
<td><code>wstreampos</code></td>
<td></td>
</tr>
<tr>
<td><code>state_type</code></td>
<td><code>mbstate_t</code></td>
<td></td>
</tr>
<tr>
<td><code>comparison_category</code></td>
<td><code><a href="../compare/strong_ordering.html">strong_ordering</a></code></td>
<td>C++20</td>
</tr>
</tbody>
</table>
<h2>例</h2>
<h3>基本的な使い方</h3>
<p><div class="yata" id="1af702e60c8463ac15f58c3f80ae5fcee1764a07"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../string.html"><string></a></span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
<span class="w"> </span><span class="c1">// <a href="basic_string.html">std::string</a>と同じ</span>
<span class="w"> </span><span class="n"><a href="basic_string.html">std::basic_string</a></span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::char_traits</span></span><span class="o"><</span><span class="kt">char</span><span class="o">>></span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"aaa"</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="basic_string.html">std::basic_string</a></span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::char_traits</span></span><span class="o"><</span><span class="kt">char</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="s">"bbb"</span><span class="p">;</span>
<span class="w"> </span><span class="c1">// char_traits::compare()で比較が行われる</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="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="s">"then"</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="s">"else"</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="p">}</span>
</code></pre></div>
</div></p>
<h4>出力</h4>
<p><pre><code>then
</code></pre></p>
<h3>大文字・小文字を区別しない文字列比較をする<code>basic_string</code>を定義 (C++20)</h3>
<p><div class="yata" id="da9b7f9fe5233935f1dcd0f4b2d63c684349d05f"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../string.html"><string></a></span>
<span class="cp">#include <a href="../compare.html"><compare></a></span>
<span class="cp">#include <a href="../cctype.html"><cctype></a></span>
<span class="cp">#include <a href="../algorithm.html"><algorithm></a></span>
<span class="k">template</span><span class="w"> </span><span class="o"><</span><span class="k">class</span><span class="w"> </span><span class="nc">T</span><span class="o">></span>
<span class="k">class</span><span class="w"> </span><span class="nc">case_insensitive_char_traits</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">base_traits</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="">std::char_traits</a></span><span class="o"><</span><span class="n">T</span><span class="o">></span><span class="p">;</span>
<span class="k">public</span><span class="o">:</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">char_type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="kt">char</span><span class="p">;</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">int_type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="kt">int</span><span class="p">;</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">off_type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">streamoff</span><span class="p">;</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">pos_type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">streampos</span><span class="p">;</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">state_type</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="kt">mbstate_t</span><span class="p">;</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">comparison_category</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="../compare/weak_ordering.html">std::weak_ordering</a></span><span class="p">;</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="nf">assign</span><span class="p">(</span><span class="n">char_type</span><span class="o">&</span><span class="w"> </span><span class="n">c1</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">&</span><span class="w"> </span><span class="n">c2</span><span class="p">)</span><span class="w"> </span><span class="k">noexcept</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">base_traits</span><span class="o">::</span><span class="n">assign</span><span class="p">(</span><span class="n">c1</span><span class="p">,</span><span class="w"> </span><span class="n">c2</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="kt">bool</span><span class="w"> </span><span class="nf">eq</span><span class="p">(</span><span class="n">char_type</span><span class="w"> </span><span class="n">c1</span><span class="p">,</span><span class="w"> </span><span class="n">char_type</span><span class="w"> </span><span class="n">c2</span><span class="p">)</span><span class="w"> </span><span class="k">noexcept</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">base_traits</span><span class="o">::</span><span class="n">eq</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c1</span><span class="p">),</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c2</span><span class="p">));</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="kt">bool</span><span class="w"> </span><span class="nf">lt</span><span class="p">(</span><span class="n">char_type</span><span class="w"> </span><span class="n">c1</span><span class="p">,</span><span class="w"> </span><span class="n">char_type</span><span class="w"> </span><span class="n">c2</span><span class="p">)</span><span class="w"> </span><span class="k">noexcept</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">base_traits</span><span class="o">::</span><span class="n">lt</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c1</span><span class="p">),</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c2</span><span class="p">));</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="nf">compare</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s1</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s2</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">n</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">auto</span><span class="w"> </span><span class="n">order</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="../algorithm/lexicographical_compare_three_way.html">std::lexicographical_compare_three_way</a></span><span class="p">(</span><span class="n">s1</span><span class="p">,</span><span class="w"> </span><span class="n">s1</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">n</span><span class="p">,</span><span class="w"> </span><span class="n">s2</span><span class="p">,</span><span class="w"> </span><span class="n">s2</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">n</span><span class="p">,</span>
<span class="w"> </span><span class="p">[](</span><span class="n">char_type</span><span class="w"> </span><span class="n">c1</span><span class="p">,</span><span class="w"> </span><span class="n">char_type</span><span class="w"> </span><span class="n">c2</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n"><a href="../compare/weak_ordering.html">std::weak_ordering</a></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">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c1</span><span class="p">)</span><span class="w"> </span><span class="o"><=></span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c2</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">order</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n"><a href="../compare/weak_ordering.html">std::weak_ordering</a></span><span class="o">::</span><span class="n">equivalent</span><span class="w"> </span><span class="o">?</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">:</span>
<span class="w"> </span><span class="n">order</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n"><a href="../compare/weak_ordering.html">std::weak_ordering</a></span><span class="o">::</span><span class="n">greater</span><span class="w"> </span><span class="o">?</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">:</span>
<span class="w"> </span><span class="mi">-1</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="nf">length</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s</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">base_traits</span><span class="o">::</span><span class="n">length</span><span class="p">(</span><span class="n">s</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="nf">find</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">n</span><span class="p">,</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">&</span><span class="w"> </span><span class="n">a</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="../algorithm/find_if.html">std::find_if</a></span><span class="p">(</span><span class="n">s</span><span class="p">,</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">n</span><span class="p">,</span><span class="w"> </span><span class="p">[</span><span class="n">a</span><span class="p">](</span><span class="n">char_type</span><span class="w"> </span><span class="n">c</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">std</span><span class="o">::</span><span class="n">tolower</span><span class="p">(</span><span class="n">c</span><span class="p">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">a</span><span class="p">;</span>
<span class="w"> </span><span class="p">});</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="nf">move</span><span class="p">(</span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s1</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s2</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">n</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">base_traits</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">s1</span><span class="p">,</span><span class="w"> </span><span class="n">s2</span><span class="p">,</span><span class="w"> </span><span class="n">n</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="nf">copy</span><span class="p">(</span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s1</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s2</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">n</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">base_traits</span><span class="o">::</span><span class="n">copy</span><span class="p">(</span><span class="n">s1</span><span class="p">,</span><span class="w"> </span><span class="n">s2</span><span class="p">,</span><span class="w"> </span><span class="n">n</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">static</span><span class="w"> </span><span class="k">constexpr</span><span class="w"> </span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="nf">assign</span><span class="p">(</span><span class="n">char_type</span><span class="o">*</span><span class="w"> </span><span class="n">s</span><span class="p">,</span><span class="w"> </span><span class="kt">size_t</span><span class="w"> </span><span class="n">n</span><span class="p">,</span><span class="w"> </span><span class="n">char_type</span><span class="w"> </span><span class="n">a</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">base_traits</span><span class="o">::</span><span class="n">assign</span><span class="p">(</span><span class="n">s</span><span class="p">,</span><span class="w"> </span><span class="n">n</span><span class="p">,</span><span class="w"> </span><span class="n">a</span><span class="p">);</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">};</span>
<span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">case_insensitive_string</span><span class="w"> </span><span class="o">=</span>
<span class="w"> </span><span class="n"><a href="basic_string.html">std::basic_string</a></span><span class="o"><</span><span class="kt">char</span><span class="p">,</span><span class="w"> </span><span class="n">case_insensitive_char_traits</span><span class="o"><</span><span class="kt">char</span><span class="o">>></span><span class="p">;</span>
<span class="w"> </span><span class="n">case_insensitive_string</span><span class="w"> </span><span class="n">a</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"AbC"</span><span class="p">;</span>
<span class="w"> </span><span class="n">case_insensitive_string</span><span class="w"> </span><span class="n">b</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"aBc"</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="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="s">"equal"</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="s">"not equal"</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="p">}</span>
</code></pre></div>
</div></p>
<h4>出力</h4>
<p><pre><code>equal
</code></pre></p>
<h2>参照</h2>
<ul>
<li><a href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1614r2.html" target="_blank">P1614R2 The Mothership has Landed</a><ul>
<li>C++20での三方比較演算子の追加と、関連する演算子の自動導出</li>
</ul>
</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>