cpprefjp.github.io/reference/chrono/duration.html at master · cpprefjp/cpprefjp.github.io

814 lines (750 loc) · 31 KB
<!doctype html>
<html class="cpprefjp" lang="ja" itemscope="" itemtype="http://schema.org/WebPage">
<!-- Google tag (gtag.js) -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-NXNBNVBTJS"></script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());
  gtag('config', 'G-NXNBNVBTJS');
        <meta charset="UTF-8">
        <title>std::chrono::duration - 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,chrono,std::chrono,class template,cpp11
        <meta name="title" content="std::chrono::duration - cpprefjp C++日本語リファレンス" />
        <meta itemprop="name" content="std::chrono::duration - cpprefjp C++日本語リファレンス" />
        <meta property="og:title" content="std::chrono::duration - cpprefjp C++日本語リファレンス" />
        <meta property="og:url" content="https://cpprefjp.github.io/reference/chrono/duration.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="`duration`は、2つの時間の間隔を表現するための型である。" />
        <meta name="twitter:card" content="summary" />
        <meta name="twitter:title" content="std::chrono::duration - cpprefjp C++日本語リファレンス" />
        <meta name="twitter:url" content="https://cpprefjp.github.io/reference/chrono/duration.html" />
        <meta name="twitter:description" content="`duration`は、2つの時間の間隔を表現するための型である。" />
  <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=557cd0469f26f0f797224f46d1b6e764266f07cc">
<link rel="icon" type="image/png" sizes="32x32" href="../../static/favicons/favicon-32x32.png?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc">
<link rel="icon" type="image/png" sizes="16x16" href="../../static/favicons/favicon-16x16.png?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc">
<link rel="manifest" href="../../manifest.json?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc">
<meta name="theme-color" content="#f5f8fc">
<link rel="stylesheet" href="../../static/pygments/default.css?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc">
<!-- <link rel="stylesheet" href="../../static/css/root.css"> -->
<link href="../../static/kunai/css/kunai-stage-0.css?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc" rel="stylesheet">
<link href="../../static/kunai/css/kunai-stage-1.css?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc" rel="stylesheet">
<link href="../../static/kunai/css/kunai-stage-2.css?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc" rel="stylesheet">
<link href="../../static/kunai/css/kunai-stage-3.css?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc" rel="stylesheet">
<script type="text/javascript" src="../../static/kunai/js/kunai-vendor.js?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc"></script>
<script type="text/javascript" src="../../static/kunai/js/kunai.js?cachebust=557cd0469f26f0f797224f46d1b6e764266f07cc"></script>
<script type="text/javascript">
  document.addEventListener('DOMContentLoaded', function() {
    var kn = new Kunai;
    kn.cpprefjp();
    </head>
<header data-kunai-mdinfo="{&#34;meta&#34;: {&#34;header&#34;: [&#34;chrono&#34;], &#34;namespace&#34;: [&#34;std::chrono&#34;], &#34;id-type&#34;: [&#34;class template&#34;], &#34;cpp&#34;: [&#34;cpp11&#34;]}, &#34;sources&#34;: [{&#34;id&#34;: &#34;740171180c227ca1acbf46a49cd825e0e7f68ed6&#34;, &#34;source&#34;: &#34;#include &lt;iostream&gt;\n#include &lt;chrono&gt;\n#include &lt;ctime&gt;\n\nusing std::chrono::system_clock;\nusing std::chrono::seconds;\n\nvoid print(const system_clock::time_point&amp; p)\n{\n  std::time_t t = system_clock::to_time_t(p);\n  char buf[26];  // \u6700\u4f4e26\u30d0\u30a4\u30c8\u304c\u5fc5\u8981\n#ifdef _MSC_VER\n  // Visual Studio\u3067\u306fctime_s()\u304c\u63a8\u5968\u3055\u308c\u3066\u3044\u308b\u3002\n  ctime_s(buf, 26, &amp;t);\n#else\n  // ctime()\u306e\u30ea\u30a8\u30f3\u30c8\u30e9\u30f3\u30c8\u7248\n  ctime_r(&amp;t, buf);\n#endif\n  // \u51fa\u529b\u3055\u308c\u305f\u6587\u5b57\u5217\u306b\u306f\u6539\u884c\u304c\u542b\u307e\u308c\u3066\u3044\u308b\u3053\u3068\u306b\u6ce8\u610f\n  std::cout &lt;&lt; buf;\n}\n\nint main()\n{\n  // \u73fe\u5728\u65e5\u6642\u3092\u53d6\u5f97\n  system_clock::time_point now = system_clock::now();\n\n  // 3\u79d2\u5f8c\u306e\u65e5\u6642\u3092\u53d6\u5f97\n  system_clock::time_point p = now + seconds(3);\n\n  print(now);\n  print(p);\n}\n&#34;}], &#34;page_id&#34;: [&#34;reference&#34;, &#34;chrono&#34;, &#34;duration&#34;]}">
  <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">
  (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);
<div class="gcse-search"></div>
            </div>
          </li>
          <li>
  <a href="https://github.com/cpprefjp/site">GitHub Project</a>
        </ul>
      </div>
        <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 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/chrono.html" itemprop="url">
                <span itemprop="name">chrono</span>
            </a>
        </span>
      </li>
      <li class="active" itemscope itemtype="http://www.schema.org/SiteNavigationElement">
        <span>
              <span itemprop="name">duration</span>
        </span>
      </li>
  <div class="crsearch"></div>
      </div>
    <div class="row">
      <div class="col-sm-12 edit-button">
    <p class="text-right"><small>
      最終更新日時:
      <time itemprop="datePublished" class="js-local-time"
            datetime="2026-08-12T17:05:51+09:00">
        2026年08月12日 17時05分51秒 (JST)
      </time>
      <br/>
      <span itemprop="author" itemscope itemtype="http://schema.org/Person">
        <span itemprop="name">Akira Takahashi</span>
      </span>
    </small></p>
    <script>
    (function () {
      // 最終更新日時を閲覧者のローカルタイムゾーンで表示し直す (issue #53 の正規化)。
      // JS が無効な環境ではサーバ生成の JST 表記がそのまま残る。
      function pad(n) { return (n < 10 ? '0' : '') + n; }
      var els = document.querySelectorAll('time.js-local-time[datetime]');
      for (var i = 0; i < els.length; i++) {
        var el = els[i];
        var d = new Date(el.getAttribute('datetime'));
        if (isNaN(d.getTime())) { continue; }
        var tz = '';
        try {
          var parts = new Intl.DateTimeFormat(undefined, { timeZoneName: 'short' }).formatToParts(d);
          for (var j = 0; j < parts.length; j++) {
            if (parts[j].type === 'timeZoneName') { tz = parts[j].value; break; }
        } catch (e) {}
        el.textContent = d.getFullYear() + '年' + pad(d.getMonth() + 1) + '月' + pad(d.getDate()) + '日 '
          + pad(d.getHours()) + '時' + pad(d.getMinutes()) + '分' + pad(d.getSeconds()) + '秒'
          + (tz ? ' (' + tz + ')' : '');
    </script>
        <p class="text-right">
          <a class="history" target="_blank" href="https://github.com/cpprefjp/site/commits/master/reference/chrono/duration.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/chrono/duration.md">
            <span class="fa fa-fw fa-pencil"></span>編集
          </a>
        </p>
      </div>
    <div class="row">
      <div class="col-sm-12 content-body">
  <div class="identifier-type">class template</div><div class="header">&lt;chrono&gt;</div><h1 itemprop="name"><span class="namespace" title="namespace std::chrono">std::chrono::</span><span class="token">duration</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="k">namespace</span><span class="w"> </span><span class="nn">chrono</span><span class="w"> </span><span class="p">{</span>
<span class="w">  </span><span class="k">template</span><span class="w"> </span><span class="o">&lt;</span><span class="k">class</span><span class="w"> </span><span class="nc">Rep</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">Period</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="../ratio.html">ratio</a></span><span class="o">&lt;</span><span class="mi">1</span><span class="o">&gt;&gt;</span>
<span class="w">  </span><span class="k">class</span><span class="w"> </span><span class="nc"><a href="">duration</a></span><span class="p">;</span>
<span class="p">}}</span>
</code></pre></div>
<h2>概要</h2>
<p><code>duration</code>は、2つの時間の間隔を表現するための型である。</p>
<p><code>duration</code>のテンプレートパラメータである<code>ratio</code>の値によって、時間のためのあらゆる単位(ナノ秒、ミリ秒、秒, etc...)を表現することができる。</p>
<p>標準では、以下の別名が提供される：</p>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>型の別名</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration_aliases.html">nanoseconds</a></code></td>
<td>ナノ秒</td>
<td>C++11</td>
<td><code><a href="duration_aliases.html">microseconds</a></code></td>
<td>マイクロ秒</td>
<td>C++11</td>
<td><code><a href="duration_aliases.html">milliseconds</a></code></td>
<td>ミリ秒</td>
<td>C++11</td>
<td><code><a href="duration_aliases.html">seconds</a></code></td>
<td>C++11</td>
<td><code><a href="duration_aliases.html">minutes</a></code></td>
<td>C++11</td>
<td><code><a href="duration_aliases.html">hours</a></code></td>
<td>C++11</td>
<td><code><a href="duration_aliases.html">days</a></code></td>
<td>C++20</td>
<td><code><a href="duration_aliases.html">weeks</a></code></td>
<td>C++20</td>
<td><code><a href="duration_aliases.html">years</a></code></td>
<td>C++20</td>
<td><code><a href="duration_aliases.html">months</a></code></td>
<td>C++20</td>
<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>
<li><code>Rep</code>が<code>duration</code>の特殊化ではないこと。</li>
<li>C++26 : <code>Rep</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>された型ではないこと。</li>
<p>これらを満たさない場合、プログラムは<a class="cpprefjp-defined-word" data-desc="プログラムが適格でないこと。コンパイルエラーなどになる" href="../../implementation-compliance.html#dfn-ill-formed">不適格</a>となる。変更不可能な<code>duration</code>が必要な場合は、<code>Rep</code>ではなく<code>duration</code>オブジェクト自体に<code>const</code>を付ける（<code>const duration&lt;int&gt;</code>のように書く）。</p>
<h2>メンバ関数</h2>
<h3>構築／コピー／破棄</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/op_constructor.html">(constructor)</a></code></td>
<td>コンストラクタ</td>
<td>C++11</td>
<td><code>~duration() = default;</code></td>
<td>デストラクタ</td>
<td>C++11</td>
<td><code>operator=(const duration&amp;) = default;</code></td>
<td>代入演算子</td>
<td>C++11</td>
<h3>観測</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/count.html">count</a></code></td>
<td>値を取得する</td>
<td>C++11</td>
<h3>算術演算</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/op_unary_plus.html">operator+</a></code></td>
<td>正の符号</td>
<td>C++11</td>
<td><code><a href="duration/op_unary_minus.html">operator-</a></code></td>
<td>負の符号 (符号反転する)</td>
<td>C++11</td>
<td><code><a href="duration/op_increment.html">operator++</a></code></td>
<td>値をインクリメントする</td>
<td>C++11</td>
<td><code><a href="duration/op_decrement.html">operator--</a></code></td>
<td>値をデクリメントする</td>
<td>C++11</td>
<td><code><a href="duration/op_plus_assign.html">operator+=</a></code></td>
<td><code>+</code>の複合代入</td>
<td>C++11</td>
<td><code><a href="duration/op_minus_assign.html">operator-=</a></code></td>
<td><code>-</code>の複合代入</td>
<td>C++11</td>
<td><code><a href="duration/op_multiply_assign.html">operator*=</a></code></td>
<td><code>*</code>の複合代入</td>
<td>C++11</td>
<td><code><a href="duration/op_divide_assign.html">operator/=</a></code></td>
<td><code>/</code>の複合代入</td>
<td>C++11</td>
<td><code><a href="duration/op_modulo_assign.html">operator%=</a></code></td>
<td><code>%</code>の複合代入</td>
<td>C++11</td>
<h2>静的メンバ関数</h2>
<h3>特別な値</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/zero.html">zero</a></code></td>
<td>初期値を取得</td>
<td>C++11</td>
<td><code><a href="duration/min.html">min</a></code></td>
<td>最小値を取得</td>
<td>C++11</td>
<td><code><a href="duration/max.html">max</a></code></td>
<td>最大値を取得</td>
<td>C++11</td>
<h2>メンバ型</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code>rep</code></td>
<td>値の数値型 <code>Rep</code></td>
<td>C++11</td>
<td><code>period</code></td>
<td>値の周期を表す型 <code>Period</code></td>
<td>C++11</td>
<h2>非メンバ関数</h2>
<h3>丸め演算</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration_cast.html">duration_cast</a></code></td>
<td>ゼロ方向への丸め</td>
<td>C++11</td>
<td><code><a href="duration/floor.html">floor</a></code></td>
<td>負の無限大方向への丸め</td>
<td>C++17</td>
<td><code><a href="duration/ceil.html">ceil</a></code></td>
<td>正の無限大方向への丸め</td>
<td>C++17</td>
<td><code><a href="duration/round.html">round</a></code></td>
<td>偶数方向への丸め</td>
<td>C++17</td>
<h3>その他数学関数</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/abs.html">abs</a></code></td>
<td>絶対値を求める</td>
<td>C++17</td>
<h3>算術演算</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/op_plus.html">operator+</a></code></td>
<td>加算</td>
<td>C++11</td>
<td><code><a href="duration/op_minus.html">operator-</a></code></td>
<td>減算</td>
<td>C++11</td>
<td><code><a href="duration/op_multiply.html">operator*</a></code></td>
<td>乗算</td>
<td>C++11</td>
<td><code><a href="duration/op_divide.html">operator/</a></code></td>
<td>除算</td>
<td>C++11</td>
<td><code><a href="duration/op_modulo.html">operator%</a></code></td>
<td>剰余算</td>
<td>C++11</td>
<h3>比較演算</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/op_equal.html">operator==</a></code></td>
<td>等値比較を行う</td>
<td>C++11</td>
<td><code><a href="duration/op_not_equal.html">operator!=</a></code></td>
<td>非等値比較を行う</td>
<td>C++11</td>
<td><code><a href="duration/op_compare_3way.html">operator&lt;=&gt;</a></code></td>
<td>三方比較を行う</td>
<td>C++20</td>
<td><code><a href="duration/op_less.html">operator&lt;</a></code></td>
<td>左辺が右辺より小さいか比較を行う</td>
<td>C++11</td>
<td><code><a href="duration/op_less_equal.html">operator&lt;=</a></code></td>
<td>左辺が右辺以下かの比較を行う</td>
<td>C++11</td>
<td><code><a href="duration/op_greater.html">operator&gt;</a></code></td>
<td>左辺が右辺より大きいか比較を行う</td>
<td>C++11</td>
<td><code><a href="duration/op_greater_equal.html">operator&gt;=</a></code></td>
<td>左辺が右辺以上かの比較を行う</td>
<td>C++11</td>
<h3>入出力</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/op_ostream.html">operator&lt;&lt;</a></code></td>
<td>ストリームへの出力</td>
<td>C++20</td>
<td><code><a href="duration/from_stream.html">from_stream</a></code></td>
<td>フォーマットを指定してストリームから入力</td>
<td>C++20</td>
<h3>リテラル</h3>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/op_ns.html">ns</a></code></td>
<td>ナノ秒リテラル</td>
<td>C++14</td>
<td><code><a href="duration/op_us.html">us</a></code></td>
<td>マイクロ秒リテラル</td>
<td>C++14</td>
<td><code><a href="duration/op_ms.html">ms</a></code></td>
<td>ミリ秒リテラル</td>
<td>C++14</td>
<td><code><a href="duration/op_s.html">s</a></code></td>
<td>秒リテラル</td>
<td>C++14</td>
<td><code><a href="duration/op_min.html">min</a></code></td>
<td>分リテラル</td>
<td>C++14</td>
<td><code><a href="duration/op_h.html">h</a></code></td>
<td>時リテラル</td>
<td>C++14</td>
<h2>共通型サポート</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="common_type.html">common_type</a></code></td>
<td>異なる<code>duration</code>間の共通の型を求める<code><a href="../type_traits/common_type.html">std::common_type</a></code>の特殊化</td>
<td>C++11</td>
<h2>文字列フォーマットサポート</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code><a href="duration/formatter.html">formatter</a></code></td>
<td>文字列フォーマットの許可。<code><a href="../format/formatter.html">std::formatter</a></code>クラスの特殊化</td>
<td>C++20</td>
<td><code><a href="duration/enable_nonlocking_formatter_optimization.html">enable_nonlocking_formatter_optimization</a></code></td>
<td><code><a href="../print/print.html">std::print()</a></code>と<code><a href="../print/println.html">std::println()</a></code>の効率的な実装を有効にする</td>
<td>C++26</td>
<h2>ハッシュサポート</h2>
<table border="1" bordercolor="#888" style="border-collapse:collapse">
<th>名前</th>
<th>説明</th>
<th>対応バージョン</th>
<td><code>template &lt;class T&gt; struct hash;</code></td>
<td><code>hash</code>クラスの先行宣言</td>
<td>C++26</td>
<td><code>template&lt;class Rep, class Period&gt;</code><br /> <code>struct hash&lt;chrono::duration&lt;Rep, Period&gt;&gt;;</code></td>
<td><code>hash</code>クラスの<code>duration</code>に対する特殊化。<code>hash&lt;Rep&gt;</code>が有効な場合のみ有効</td>
<td>C++26</td>
<p><div class="yata" id="740171180c227ca1acbf46a49cd825e0e7f68ed6"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../iostream.html">&lt;iostream&gt;</a></span>
<span class="cp">#include <a href="../chrono.html">&lt;chrono&gt;</a></span>
<span class="cp">#include <a href="../ctime.html">&lt;ctime&gt;</a></span>
<span class="k">using</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">chrono</span><span class="o">::</span><span class="n"><a href="system_clock.html">system_clock</a></span><span class="p">;</span>
<span class="k">using</span><span class="w"> </span><span class="n"><a href="duration_aliases.html">std::chrono::seconds</a></span><span class="p">;</span>
<span class="kt">void</span><span class="w"> </span><span class="nf">print</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n"><a href="system_clock.html">system_clock</a></span><span class="o">::</span><span class="n">time_point</span><span class="o">&amp;</span><span class="w"> </span><span class="n">p</span><span class="p">)</span>
<span class="p">{</span>
<span class="w">  </span><span class="n"><a href="../ctime/time_t.html">std::time_t</a></span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="system_clock.html">system_clock</a></span><span class="o">::</span><span class="n"><a href="system_clock/to_time_t.html">to_time_t</a></span><span class="p">(</span><span class="n">p</span><span class="p">);</span>
<span class="w">  </span><span class="kt">char</span><span class="w"> </span><span class="n">buf</span><span class="p">[</span><span class="mi">26</span><span class="p">];</span><span class="w">  </span><span class="c1">// 最低26バイトが必要</span>
<span class="cp">#ifdef _MSC_VER</span>
<span class="w">  </span><span class="c1">// Visual Studioではctime_s()が推奨されている。</span>
<span class="w">  </span><span class="n">ctime_s</span><span class="p">(</span><span class="n">buf</span><span class="p">,</span><span class="w"> </span><span class="mi">26</span><span class="p">,</span><span class="w"> </span><span class="o">&amp;</span><span class="n">t</span><span class="p">);</span>
<span class="cp">#else</span>
<span class="w">  </span><span class="c1">// ctime()のリエントラント版</span>
<span class="w">  </span><span class="n">ctime_r</span><span class="p">(</span><span class="o">&amp;</span><span class="n">t</span><span class="p">,</span><span class="w"> </span><span class="n">buf</span><span class="p">);</span>
<span class="cp">#endif</span>
<span class="w">  </span><span class="c1">// 出力された文字列には改行が含まれていることに注意</span>
<span class="w">  </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o">&lt;&lt;</span><span class="w"> </span><span class="n">buf</span><span class="p">;</span>
<span class="p">}</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">// 現在日時を取得</span>
<span class="w">  </span><span class="n"><a href="system_clock.html">system_clock</a></span><span class="o">::</span><span class="n">time_point</span><span class="w"> </span><span class="n">now</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="system_clock.html">system_clock</a></span><span class="o">::</span><span class="n"><a href="system_clock/now.html">now()</a></span><span class="p">;</span>
<span class="w">  </span><span class="c1">// 3秒後の日時を取得</span>
<span class="w">  </span><span class="n"><a href="system_clock.html">system_clock</a></span><span class="o">::</span><span class="n">time_point</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">now</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n"><a href="duration_aliases.html">seconds</a></span><span class="p">(</span><span class="mi">3</span><span class="p">);</span>
<span class="w">  </span><span class="n">print</span><span class="p">(</span><span class="n">now</span><span class="p">);</span>
<span class="w">  </span><span class="n">print</span><span class="p">(</span><span class="n">p</span><span class="p">);</span>
<span class="p">}</span>
</code></pre></div>
<h3>出力例</h3>
<p><pre><code>Tue Oct 16 16:25:08 2012
Tue Oct 16 16:25:11 2012
</code></pre></p>
<h2>バージョン</h2>
<h3>言語</h3>
<li>C++11</li>
<h3>処理系</h3>
<li><a href="../../implementation.html#gcc">GCC</a>: 4.7.0 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../implementation.html#visual_cpp">Visual C++</a>: 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>, 2015 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../implementation.html#clang">Clang</a>: 14.0.6 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<h2>参照</h2>
<li><a href="https://open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2592r3.html" target="_blank">P2592R3 Hashing support for <code>std::chrono</code> value classes</a><ul>
<li>C++26でハッシュサポートが追加された</li>
<li><a href="https://cplusplus.github.io/LWG/issue4481" target="_blank">LWG Issue 4481. Disallow <code>chrono::duration&lt;const T, P&gt;</code></a><ul>
<li>C++26で、テンプレートパラメータ<code>Rep</code>に<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>された型を指定した場合に<a class="cpprefjp-defined-word" data-desc="プログラムが適格でないこと。コンパイルエラーなどになる" href="../../implementation-compliance.html#dfn-ill-formed">不適格</a>となることが規定された。<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>Rep</code>はメンバ演算子・ハッシュ・汎用の算術コードで問題を起こすため、<code>const</code>は<code>Rep</code>ではなく<code>duration</code>オブジェクト自体に付けるべきである</li>
</ul></div>
      </div>
    <div id="sidebar" class="col-sm-3 col-sm-pull-9">
            </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>
    </body>
Navigation Menu

Uh oh!

Uh oh!

FilesExpand file tree

duration.html

Latest commit

History

duration.html

File metadata and controls
