-
Notifications
You must be signed in to change notification settings - Fork 1
Expand file tree
/
Copy pathstold.html
More file actions
418 lines (345 loc) · 38.4 KB
/
stold.html
File metadata and controls
418 lines (345 loc) · 38.4 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
<!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>stold - 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,function,cpp11
">
<meta name="title" content="stold - cpprefjp C++日本語リファレンス" />
<meta itemprop="name" content="stold - cpprefjp C++日本語リファレンス" />
<meta property="og:title" content="stold - cpprefjp C++日本語リファレンス" />
<meta property="og:url" content="https://cpprefjp.github.io/reference/string/stold.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="文字列`str`を数値として読み取って、`long double`型の値に変換する。" />
<meta name="twitter:card" content="summary" />
<meta name="twitter:title" content="stold - cpprefjp C++日本語リファレンス" />
<meta name="twitter:url" content="https://cpprefjp.github.io/reference/string/stold.html" />
<meta name="twitter:description" content="文字列`str`を数値として読み取って、`long double`型の値に変換する。" />
<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": ["function"], "cpp": ["cpp11"]}, "sources": [{"id": "b1c147c469fb245df3b6e4849f0860e50713d2c2", "source": "#include <iostream>\n#include <string>\n\nint main()\n{\n // 10\u9032\u6cd5\u3067\u306e\u5909\u63db\n std::cout << \"---- decimal point\" << std::endl;\n\n long double a = std::stold(\"1.5\"); // std::stold(\"1.5\", nullptr);\n std::cout << a << std::endl;\n\n long double aw = std::stold(L\"1.\"); // std::stold(L\"1.\", nullptr);\n std::cout << aw << std::endl;\n\n // \u6307\u6570\u8868\u8a18\u306e\u5909\u63db\n std::cout << \"---- base = 8\" << std::endl;\n\n long double b = std::stold(\"0.5e3\", nullptr);\n std::cout << b << std::endl;\n\n long double bw = std::stold(L\".25e3\", nullptr);\n std::cout << bw << std::endl;\n\n // 16\u9032\u6cd5\u3067\u306e\u5909\u63db\n std::cout << \"---- base = 16\" << std::endl;\n\n long double c = std::stold(\"0x1.2P3\", nullptr);\n std::cout << c << std::endl;\n\n long double cw = std::stold(L\"0x1.2P4\", nullptr);\n std::cout << cw << std::endl;\n\n // 2\u756a\u76ee\u306e\u4eee\u5f15\u6570\u306e\u4f7f\u7528\u4f8b\n std::cout << \"---- use of idx parameter\" << std::endl;\n\n std::string es = \"30.75%\";\n std::size_t ei;\n long double e = std::stold(es, &ei);\n std::cout << e << ' ' << es[ei] << std::endl;\n\n std::wstring ews = L\"32%\";\n std::size_t ewi;\n long double ew = std::stold(ews, &ewi);\n std::cout << ew << ' ' << ewi << std::endl;\n\n // \u6587\u5b57\u5217\u5148\u982d\u306b\u7a7a\u767d\u304c\u3042\u308b\u5834\u5408\n std::cout << \"---- space character before number\" << std::endl;\n std::cout << std::stold(\" -1\") << std::endl;\n std::cout << std::stold(L\" -.25\") << std::endl;\n}\n"}], "page_id": ["reference", "string", "stold"]}">
<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">stold</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="2025-12-03T13:42:25">
2025年12月03日 13時42分25秒
</span>
<br/>
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
<span itemprop="name">K10-K10</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/stold.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/stold.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">function</div><div class="header"><string></div><h1 itemprop="name"><span class="namespace" title="namespace std">std::</span><span class="token">stold</span><span class="cpp cpp11" title="C++11で追加">(C++11)</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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="nf">stold</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n"><a href="basic_string.html">std::string</a></span><span class="o">&</span><span class="w"> </span><span class="n">str</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="o">*</span><span class="w"> </span><span class="n">idx</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">);</span><span class="w"> </span><span class="c1">// (1)</span>
<span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="nf">stold</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n"><a href="basic_string.html">std::wstring</a></span><span class="o">&</span><span class="w"> </span><span class="n">str</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="o">*</span><span class="w"> </span><span class="n">idx</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">);</span><span class="w"> </span><span class="c1">// (2)</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h2>概要</h2>
<p>文字列<code>str</code>を数値として読み取って、<code>long double</code>型の値に変換する。</p>
<h2>効果</h2>
<p>パラメータ<code>str</code>が<code>string</code>型であれば<code>std::strtold(str.c_str(), &end)</code>、<code>wstring</code>型であれば<code>std::wcstold(str.c_str(), &end)</code>を呼び出して、その<a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>を返す。</p>
<p><code>idx</code>が非<code>nullptr</code>の場合、変換に使用されなかった要素のインデックス（<code>end - str.c_str()</code>）が格納される。</p>
<h2><a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a></h2>
<p>変換して得られた数値が返される。</p>
<h2><a class="cpprefjp-defined-word" data-desc="問題が発生したときに、現在実行位置を過去に通過・記録した位置に戻し、文脈情報を添えて紐づけられた処理(例外ハンドラー)を呼び出す仕組み。またはその事態">例外</a></h2>
<ul>
<li>数値への変換が行われなかった場合、<code>std::invalid_argument</code>が送出される。</li>
<li>以下の条件に合致した場合、<code><a href="../stdexcept.html">std::out_of_range</a></code>が送出される。<ul>
<li><code>std::strtold()</code>関数が<code><a href="../cerrno/errno.html">errno</a></code>変数に<code><a href="../cerrno.html">ERANGE</a></code>を設定した場合</li>
<li>結果が範囲外の値になった場合 (C++14)</li>
</ul>
</li>
</ul>
<h2>備考</h2>
<h3>errnoの扱い</h3>
<ul>
<li>Visual C++ 11やGCC (libstdc++) 4.8.2では、この関数を呼び出すと<code>errno</code>の値が変更される。</li>
<li>Clang (libc++) 3.3では、この関数の呼び出し前後で<code>errno</code>の値は変化しない。</li>
</ul>
<h3>グローバルロケールの影響</h3>
<p>この関数は、<code><a href="../clocale/setlocale.html">setlocale()</a></code>関数により挙動が変化する。</p>
<ul>
<li><code>strtold()</code>関数での文字列先頭の空白を読み飛ばす処理に、<code><cctype></code>の<code>isspace()</code>関数が使用される。</li>
<li>小数点記号は<code>LC_NUMERIC</code>で指定されたものが使用される。</li>
</ul>
<h2>例</h2>
<p><div class="yata" id="b1c147c469fb245df3b6e4849f0860e50713d2c2"><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">// 10進法での変換</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">"---- decimal point"</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="kt">long</span><span class="w"> </span><span class="kt">double</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"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="s">"1.5"</span><span class="p">);</span><span class="w"> </span><span class="c1">// <span style="color:#ff0000">std::stold</span>("1.5", nullptr);</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</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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">aw</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="sa">L</span><span class="s">"1."</span><span class="p">);</span><span class="w"> </span><span class="c1">// <span style="color:#ff0000">std::stold</span>(L"1.", nullptr);</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">aw</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="c1">// 指数表記の変換</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">"---- base = 8"</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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">b</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="s">"0.5e3"</span><span class="p">,</span><span class="w"> </span><span class="k">nullptr</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">b</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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">bw</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="sa">L</span><span class="s">".25e3"</span><span class="p">,</span><span class="w"> </span><span class="k">nullptr</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">bw</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="c1">// 16進法での変換</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">"---- base = 16"</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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">c</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="s">"0x1.2P3"</span><span class="p">,</span><span class="w"> </span><span class="k">nullptr</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">c</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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">cw</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="sa">L</span><span class="s">"0x1.2P4"</span><span class="p">,</span><span class="w"> </span><span class="k">nullptr</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">cw</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="c1">// 2番目の仮引数の使用例</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">"---- use of idx parameter"</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="n"><a href="basic_string.html">std::string</a></span><span class="w"> </span><span class="n">es</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"30.75%"</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="w"> </span><span class="n">ei</span><span class="p">;</span>
<span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">e</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="n">es</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">ei</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">e</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="sc">' '</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">es</span><span class="p">[</span><span class="n">ei</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="n"><a href="basic_string.html">std::wstring</a></span><span class="w"> </span><span class="n">ews</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="sa">L</span><span class="s">"32%"</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="w"> </span><span class="n">ewi</span><span class="p">;</span>
<span class="w"> </span><span class="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">ew</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="n">ews</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">ewi</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">ew</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="sc">' '</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">ewi</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="c1">// 文字列先頭に空白がある場合</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">"---- space character before number"</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="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"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="s">" -1"</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="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"><span style="color:#ff0000">std::stold</span></span><span class="p">(</span><span class="sa">L</span><span class="s">" -.25"</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="p">}</span>
</code></pre></div>
</div></p>
<h3>出力例</h3>
<p><pre><code>---- decimal point
1.5
1
---- base = 8
500
250
---- base = 16
9
18
---- use of idx parameter
30.75 %
32 2
---- space character before number
-1
-0.25
</code></pre></p>
<h2>実装例</h2>
<p><div class="codehilite"><pre><span></span><code><span class="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="nf">stold</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n"><a href="basic_string.html">std::string</a></span><span class="o">&</span><span class="w"> </span><span class="n">str</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="o">*</span><span class="w"> </span><span class="n">idx</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="o">*</span><span class="w"> </span><span class="n">p</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="basic_string/c_str.html">str.c_str()</a></span><span class="p">;</span>
<span class="w"> </span><span class="kt">char</span><span class="o">*</span><span class="w"> </span><span class="n">end</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../cerrno/errno.html">errno</a></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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">x</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">strtold</span><span class="p">(</span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">end</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">p</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">end</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">throw</span><span class="w"> </span><span class="n"><a href="../stdexcept.html">std::invalid_argument</a></span><span class="p">(</span><span class="s">"stold"</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 href="../cerrno/errno.html">errno</a></span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n"><a href="../cerrno.html">ERANGE</a></span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">throw</span><span class="w"> </span><span class="n"><a href="../stdexcept.html">std::out_of_range</a></span><span class="p">(</span><span class="s">"stold"</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">idx</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="o">*</span><span class="n">idx</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="o">></span><span class="p">(</span><span class="n">end</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">p</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">x</span><span class="p">;</span>
<span class="p">}</span>
<span class="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="nf">stold</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n"><a href="basic_string.html">std::wstring</a></span><span class="o">&</span><span class="w"> </span><span class="n">str</span><span class="p">,</span><span class="w"> </span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="o">*</span><span class="w"> </span><span class="n">idx</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">wchar_t</span><span class="o">*</span><span class="w"> </span><span class="n">p</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="basic_string/c_str.html">str.c_str()</a></span><span class="p">;</span>
<span class="w"> </span><span class="kt">wchar_t</span><span class="o">*</span><span class="w"> </span><span class="n">end</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../cerrno/errno.html">errno</a></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="kt">long</span><span class="w"> </span><span class="kt">double</span><span class="w"> </span><span class="n">x</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">wcstold</span><span class="p">(</span><span class="n">p</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">end</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">p</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">end</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">throw</span><span class="w"> </span><span class="n"><a href="../stdexcept.html">std::invalid_argument</a></span><span class="p">(</span><span class="s">"stold"</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 href="../cerrno/errno.html">errno</a></span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n"><a href="../cerrno.html">ERANGE</a></span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="k">throw</span><span class="w"> </span><span class="n"><a href="../stdexcept.html">std::out_of_range</a></span><span class="p">(</span><span class="s">"stold"</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">idx</span><span class="w"> </span><span class="o">!=</span><span class="w"> </span><span class="k">nullptr</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="o">*</span><span class="n">idx</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">static_cast</span><span class="o"><</span><span class="n"><a href="../cstddef/size_t.html">std::size_t</a></span><span class="o">></span><span class="p">(</span><span class="n">end</span><span class="w"> </span><span class="o">-</span><span class="w"> </span><span class="n">p</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">x</span><span class="p">;</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h2>バージョン</h2>
<h3>言語</h3>
<ul>
<li>C++11</li>
</ul>
<h3>処理系</h3>
<ul>
<li><a href="../../implementation.html#clang">Clang</a>: ?</li>
<li><a href="../../implementation.html#gcc">GCC</a>: ?</li>
<li><a href="../../implementation.html#icc">ICC</a>: ?</li>
<li><a href="../../implementation.html#visual_cpp">Visual C++</a>: 2010 <span aria-label="検証済" role="img" title="検証済">✅</span>, 2012 <span aria-label="検証済" role="img" title="検証済">✅</span>, 2013 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
</ul>
<p>ただし、Visual C++ 10.0, 11.0は十六進法に対応していない（12.0は未確認）。</p>
<h2>関連リンク</h2>
<h3>C標準ライブラリに由来する関数</h3>
<ul>
<li><code>atof</code>: <code>stold</code>は<code>atof</code>を<code>std::string</code>および<code>std::wstring</code>に対応させ、<a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型を<code>long double</code>に変更したものと見なせる。</li>
<li><code>strtold</code>, <code>wcstold</code>: <code>stold</code>は<code>strtold</code>および<code>wcstold</code>をそれぞれ<code>std::string</code>と<code>std::wstring</code>に対応させたものと見なせる。</li>
</ul>
<h3>ファミリー</h3>
<ul>
<li><code><a href="stoi.html">stoi</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>int</code>となったもの。</li>
<li><code><a href="stol.html">stol</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>long</code>となったもの。</li>
<li><code><a href="stoll.html">stoll</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>long long</code>となったもの。</li>
<li><code><a href="stoul.html">stoul</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>unsigned long</code>となったもの。</li>
<li><code><a href="stoull.html">stoull</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>unsigned long long</code>となったもの。</li>
<li><code><a href="stof.html">stof</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>float</code>となったもの。</li>
<li><code><a href="stod.html">stod</a></code>: <a class="cpprefjp-defined-word" data-desc="関数呼び出し式の評価結果となるオブジェクト・値">戻り値</a>の型が<code>double</code>となったもの。</li>
<li>(<code>stold</code>: この関数自身)</li>
</ul>
<h3>ロケール依存しない高速な変換関数</h3>
<ul>
<li><code><a href="../charconv/from_chars.html">from_chars</a></code></li>
</ul>
<h2>参照</h2>
<ul>
<li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2408.html" target="_blank">N2408 Simple Numeric Access Revision 2</a></li>
<li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2009" target="_blank">LWG Issue 2009. Reporting out-of-bound values on numeric string conversions</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>