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<header data-kunai-mdinfo="{"meta": {"header": ["chrono"], "namespace": ["std::chrono"], "id-type": ["type-alias"], "cpp": ["cpp20"], "alias": ["utc_seconds"]}, "sources": [{"id": "014a7d5ebfac0ef78c9b0d9fe70e1a776cbcecb9", "source": "#include <iostream>\n#include <chrono>\n\nnamespace chrono = std::chrono;\n\nint main()\n{\n // \u672a\u898f\u5b9a\u306e\u6642\u9593\u9593\u9694\u5358\u4f4d\u3092\u3082\u3064\u6642\u9593\u70b9\n chrono::utc_clock::time_point tp = chrono::utc_clock::now();\n\n // \u79d2\u5358\u4f4d\u306e\u6642\u9593\u70b9 (\u65e5\u4ed8\u3068\u6642\u9593\u304c\u51fa\u529b\u3055\u308c\u308b)\n chrono::utc_seconds sec_p = chrono::time_point_cast<chrono::seconds>(tp);\n std::cout << sec_p << std::endl;\n}\n"}, {"id": "6c5dda781b44e4f5a768375311cf550d16d80d3b", "source": "#include <iostream>\n#include <sstream>\n#include <chrono>\n#include <string>\n\nnamespace chrono = std::chrono;\n\nint main()\n{\n // \u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3068\u30aa\u30d5\u30bb\u30c3\u30c8\u3092\u542b\u307e\u306a\u3044\u5165\u529b\n {\n std::stringstream ss;\n ss << \"2019-10-24 20:15:10\";\n\n chrono::utc_seconds tp;\n chrono::from_stream(ss, \"%Y-%m-%d %H:%M:%S\", tp);\n\n if (ss) {\n std::cout << tp << std::endl;\n }\n else {\n std::cout << \"\u89e3\u6790\u5931\u6557\" << std::endl;\n }\n }\n\n // \u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u3068\u30aa\u30d5\u30bb\u30c3\u30c8\u3092\u542b\u3080\u5165\u529b\n {\n std::stringstream ss;\n ss << \"2019-10-24 20:15:10 UTC +0900\";\n\n chrono::utc_seconds tp;\n std::string abbrev;\n chrono::minutes offset{0};\n chrono::from_stream(ss, \"%Y-%m-%d %H:%M:%S %Z %z\", tp, &abbrev, &offset);\n\n std::cout << tp << std::endl;\n std::cout << abbrev << std::endl;\n std::cout << offset.count() << std::endl;\n }\n}\n"}, {"id": "72d5bbe833bc6525a1cdb737348a3ed6cc82593e", "source": "#include <iostream>\n#include <chrono>\n#include <format>\n\nnamespace chrono = std::chrono;\n\nint main()\n{\n chrono::utc_clock::time_point now = chrono::utc_clock::now();\n chrono::utc_seconds now_sec = chrono::floor<chrono::seconds>(now);\n\n // \u30c7\u30d5\u30a9\u30eb\u30c8\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\n std::cout << std::format(\"1 : {}\", now_sec) << std::endl;\n\n // \u300c\u5e74\u6708\u65e5 \u6642\u5206\u79d2\u300d\u306e\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\n std::cout << std::format(\"2 : {:%Y\u5e74%m\u6708%d\u65e5 %H\u6642%M\u5206%S\u79d2}\", now_sec) << std::endl;\n\n // \u65e5\u4ed8\u3092 / (\u30b9\u30e9\u30c3\u30b7\u30e5) \u533a\u5207\u308a\u3001\u6642\u9593\u3092 : (\u30b3\u30ed\u30f3) \u533a\u5207\u308a\u3001\u30bf\u30a4\u30e0\u30be\u30fc\u30f3\u306e\u7565\u79f0\u4ed8\u304d\n std::cout << std::format(\"3 : {0:%Y/%m/%d %H:%M:%S %Z}\", now_sec) << std::endl;\n\n // \u65e5\u4ed8\u3060\u3051\u51fa\u529b\n std::cout << std::format(\"4 : {:%Y\u5e74%m\u6708%d\u65e5}\", now_sec) << std::endl;\n std::cout << std::format(\"5 : {:%F}\", now_sec) << std::endl;\n\n // \u6642\u9593\u3060\u3051\u51fa\u529b\n std::cout << std::format(\"6 : {:%H\u6642%M\u5206%S\u79d2}\", now_sec) << std::endl;\n std::cout << std::format(\"7 : {:%T}\", now_sec) << std::endl;\n}\n"}], "page_id": ["reference", "chrono", "utc_time"]}">
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<div class="identifier-type">type-alias</div><div class="header"><chrono></div><h1 itemprop="name"><span class="namespace" title="namespace std::chrono">std::chrono::</span><span class="token">utc_time</span><span class="cpp cpp20" title="C++20で追加">(C++20)</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="o">::</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"><</span><span class="k">class</span><span class="w"> </span><span class="nc">Duration</span><span class="o">></span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">utc_time</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="time_point.html">time_point</a></span><span class="o"><</span><span class="n"><a href="utc_clock.html">utc_clock</a></span><span class="p">,</span><span class="w"> </span><span class="n">Duration</span><span class="o">></span><span class="p">;</span><span class="w"> </span><span class="c1">// (1) C++20</span>
<span class="w"> </span><span class="k">using</span><span class="w"> </span><span class="n">utc_seconds</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">utc_time</span><span class="o"><</span><span class="n"><a href="duration_aliases.html">seconds</a></span><span class="o">></span><span class="p">;</span><span class="w"> </span><span class="c1">// (2) C++20</span>
<span class="w"> </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">charT</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">traits</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">Duration</span><span class="o">></span>
<span class="w"> </span><span class="n"><a href="../ostream/basic_ostream.html">std::basic_ostream</a></span><span class="o"><</span><span class="n">charT</span><span class="p">,</span><span class="w"> </span><span class="n">traits</span><span class="o">>&</span>
<span class="w"> </span><span class="k">operator</span><span class="o"><<</span><span class="p">(</span><span class="n"><a href="../ostream/basic_ostream.html">std::basic_ostream</a></span><span class="o"><</span><span class="n">charT</span><span class="p">,</span><span class="w"> </span><span class="n">traits</span><span class="o">>&</span><span class="w"> </span><span class="n">os</span><span class="p">,</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">utc_time</span><span class="o"><</span><span class="n">Duration</span><span class="o">>&</span><span class="w"> </span><span class="n">tp</span><span class="p">);</span><span class="w"> </span><span class="c1">// (3) C++20</span>
<span class="w"> </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">charT</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">traits</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">Duration</span><span class="p">,</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">Alloc</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="../memory/allocator.html">std::allocator</a></span><span class="o"><</span><span class="n">charT</span><span class="o">>></span>
<span class="w"> </span><span class="n"><a href="../istream/basic_istream.html">std::basic_istream</a></span><span class="o"><</span><span class="n">charT</span><span class="p">,</span><span class="w"> </span><span class="n">traits</span><span class="o">>&</span>
<span class="w"> </span><span class="n">from_stream</span><span class="p">(</span><span class="n"><a href="../istream/basic_istream.html">std::basic_istream</a></span><span class="o"><</span><span class="n">charT</span><span class="p">,</span><span class="w"> </span><span class="n">traits</span><span class="o">>&</span><span class="w"> </span><span class="n">is</span><span class="p">,</span>
<span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">charT</span><span class="o">*</span><span class="w"> </span><span class="n">fmt</span><span class="p">,</span>
<span class="w"> </span><span class="n">utc_time</span><span class="o"><</span><span class="n">Duration</span><span class="o">>&</span><span class="w"> </span><span class="n">tp</span><span class="p">,</span>
<span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::basic_string</a></span><span class="o"><</span><span class="n">charT</span><span class="p">,</span><span class="w"> </span><span class="n">traits</span><span class="p">,</span><span class="w"> </span><span class="n">Alloc</span><span class="o">>*</span><span class="w"> </span><span class="n">abbrev</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">nullptr</span><span class="p">,</span>
<span class="w"> </span><span class="n"><a href="duration_aliases.html">minutes</a></span><span class="o">*</span><span class="w"> </span><span class="n">offset</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nb">nullptr</span><span class="p">);</span><span class="w"> </span><span class="c1">// (4) C++20</span>
<span class="p">}</span>
<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="w"> </span><span class="o"><</span><span class="k">class</span><span class="w"> </span><span class="nc">Duration</span><span class="p">,</span><span class="w"> </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">formatter</span><span class="o"><</span><span class="n">chrono</span><span class="o">::</span><span class="n">utc_time</span><span class="o"><</span><span class="n">Duration</span><span class="o">></span><span class="p">,</span><span class="w"> </span><span class="n">charT</span><span class="o">></span><span class="p">;</span><span class="w"> </span><span class="c1">// (5) C++20</span>
<span class="p">}</span>
</code></pre></div>
</p>
<h2>概要</h2>
<p>UTC時間の一点を指す<code><a href="time_point.html">time_point</a></code>に対する別名。</p>
<ul>
<li>(1) : <code><a href="utc_clock.html">utc_clock</a></code>の<code><a href="time_point.html">time_point</a></code>に対する別名。時間間隔を表す型はパラメータ化されている</li>
<li>(2) : 秒単位でUTC時間の一点を指す<code><a href="time_point.html">time_point</a></code>に対する別名</li>
<li>(3) : 時間点に含まれる日付と時間を出力ストリームに出力する</li>
<li>(4) : フォーマット指定して入力ストリームから日付・時間を時間点オブジェクトに入力する</li>
<li>(5) : <code>utc_time</code>型に対する<code><a href="../format/formatter.html">std::formatter</a></code>クラステンプレートの特殊化</li>
</ul>
<h2>効果</h2>
<p>便宜上のリテラルキャスト<code>STATICALLY-WIDEN</code>を導入する。<code>STATICALLY-WIDEN<charT>("...")</code>は、<code>charT</code>が<code>char</code>である場合は<code>"..."</code>、<code>charT</code>が<code>wchar_t</code>である場合は<code>L"..."</code>を意味する。</p>
<ul>
<li>
<p>(3) : 以下と等価：
<br />
<div class="codehilite"><pre><span></span><code><span class="k">return</span><span class="w"> </span><span class="n">os</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="format.html">format</a></span><span class="p">(</span><span class="n"><a href="../ios/ios_base/getloc.html">os.getloc()</a></span><span class="p">,</span><span class="w"> </span><span class="n">STATICALLY</span><span class="o">-</span><span class="n">WIDEN</span><span class="o"><</span><span class="n">charT</span><span class="o">></span><span class="p">(</span><span class="s">"{:L%F %T}"</span><span class="p">),</span><span class="w"> </span><span class="n">tp</span><span class="p">);</span>
</code></pre></div>
</p>
</li>
<li>
<p>(4) :</p>
<ul>
<li>パラメータ<code>fmt</code>で指定されたフォーマットフラグを使用して、入力を解析し、<code>tp</code>に代入する</li>
<li>有効な日付・時間の解析に失敗した場合、<code>is.<a href="../ios/basic_ios/setstate.html">setstate</a>(<a href="../ios/ios_base/type-iostate.html">ios_base::failbit</a>)</code>が呼び出され、パラメータ<code>tp</code>は変更されない</li>
<li>タイムゾーンフォーマット<code>"%Z"</code>が指定され、解析が成功した場合、パラメータ<code>abbrev</code>が非ヌルである場合に<code>*abbrev</code>にタイムゾーン名が代入される</li>
<li>タイムゾーンとしてUTC時間からのオフセット時間 (日本なら<code>"+0900"</code>) を意味するフォーマット<code>"%z"</code>が指定され、解析が成功した場合、パラメータ<code>offset</code>が非ヌルである場合に<code>*offset</code>にその値が代入される</li>
<li>さらに、<code>tp</code>に日付・時間が代入される前に、解析されたオフセットがタイムスタンプから引かれる</li>
<li><code>is</code>を返す</li>
</ul>
</li>
</ul>
<h2>備考</h2>
<ul>
<li>(1) : このバージョンは、関数テンプレートで任意の時間間隔単位の<code>time_point</code>を受け取るために使用できる。<code>utc_clock::time_point</code>がもつ時間間隔の単位は<a class="cpprefjp-defined-word" data-desc="未規定の動作。事前の断りなく処理系によって異なる動作をする" href="../../implementation-compliance.html#dfn-unspecified-behavior">未規定</a> (<a class="cpprefjp-defined-word" data-desc="処理系定義の動作。処理系によって事前に定めた動作をする" href="../../implementation-compliance.html#dfn-implementation-defined-behavior">実装定義</a>) であるため、特定の単位に決めることができないため、時間間隔の型のみをパラメータ化して関数テンプレートで受け取ると便利である</li>
<li>(5) :<ul>
<li><code>%Z</code> (タイムゾーンの略称) が指定された場合、<code>STATICALLY-WIDEN<charT>("UTC")</code>で置き換えられる</li>
<li><code>%z</code>もしくはその改良コマンドが指定された場合、<code>0<a href="duration/op_min.html">min</a></code>が使用される</li>
<li>引数が正のうるう秒が挿入された時間を表す場合、秒フィールドは<code>STATICALLY-WIDEN<charT>("60")</code>でフォーマットされる</li>
</ul>
</li>
</ul>
<h2>例</h2>
<h3>基本的な使い方</h3>
<p><div class="yata" id="014a7d5ebfac0ef78c9b0d9fe70e1a776cbcecb9"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../chrono.html"><chrono></a></span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">chrono</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nn">std</span><span class="o">::</span><span class="nn">chrono</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">// 未規定の時間間隔単位をもつ時間点</span>
<span class="w"> </span><span class="n"><a href="utc_clock.html">chrono::utc_clock</a></span><span class="o">::</span><span class="n">time_point</span><span class="w"> </span><span class="n">tp</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="utc_clock.html">chrono::utc_clock</a></span><span class="o">::</span><span class="n"><a href="utc_clock/now.html">now()</a></span><span class="p">;</span>
<span class="w"> </span><span class="c1">// 秒単位の時間点 (日付と時間が出力される)</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">chrono::utc_seconds</span></span><span class="w"> </span><span class="n">sec_p</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="time_point_cast.html">chrono::time_point_cast</a></span><span class="o"><</span><span class="n"><a href="duration_aliases.html">chrono::seconds</a></span><span class="o">></span><span class="p">(</span><span class="n">tp</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">sec_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>
<h4>出力例</h4>
<p><pre><code>2019-10-24 11:15:10
</code></pre></p>
<h3>入力の例</h3>
<p><div class="yata" id="6c5dda781b44e4f5a768375311cf550d16d80d3b"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../sstream.html"><sstream></a></span>
<span class="cp">#include <a href="../chrono.html"><chrono></a></span>
<span class="cp">#include <a href="../string.html"><string></a></span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">chrono</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nn">std</span><span class="o">::</span><span class="nn">chrono</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">// タイムゾーンとオフセットを含まない入力</span>
<span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">stringstream</span><span class="w"> </span><span class="n">ss</span><span class="p">;</span>
<span class="w"> </span><span class="n">ss</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"2019-10-24 20:15:10"</span><span class="p">;</span>
<span class="w"> </span><span class="n">chrono</span><span class="o">::</span><span class="n">utc_seconds</span><span class="w"> </span><span class="n">tp</span><span class="p">;</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">chrono::from_stream</span></span><span class="p">(</span><span class="n">ss</span><span class="p">,</span><span class="w"> </span><span class="s">"%Y-%m-%d %H:%M:%S"</span><span class="p">,</span><span class="w"> </span><span class="n">tp</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">ss</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">tp</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">"解析失敗"</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="p">}</span>
<span class="w"> </span><span class="c1">// タイムゾーンとオフセットを含む入力</span>
<span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">stringstream</span><span class="w"> </span><span class="n">ss</span><span class="p">;</span>
<span class="w"> </span><span class="n">ss</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"2019-10-24 20:15:10 UTC +0900"</span><span class="p">;</span>
<span class="w"> </span><span class="n">chrono</span><span class="o">::</span><span class="n">utc_seconds</span><span class="w"> </span><span class="n">tp</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="../string/basic_string.html">std::string</a></span><span class="w"> </span><span class="n">abbrev</span><span class="p">;</span>
<span class="w"> </span><span class="n"><a href="duration_aliases.html">chrono::minutes</a></span><span class="w"> </span><span class="n">offset</span><span class="p">{</span><span class="mi">0</span><span class="p">};</span>
<span class="w"> </span><span class="n"><span style="color:#ff0000">chrono::from_stream</span></span><span class="p">(</span><span class="n">ss</span><span class="p">,</span><span class="w"> </span><span class="s">"%Y-%m-%d %H:%M:%S %Z %z"</span><span class="p">,</span><span class="w"> </span><span class="n">tp</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">abbrev</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">offset</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">tp</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">abbrev</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"><a href="duration/count.html">offset.count()</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="../ostream/endl.html">std::endl</a></span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
</code></pre></div>
</div></p>
<h4>出力例</h4>
<p><pre><code>2019-10-24 11:15:10
2019-10-24 11:15:10
UTC
540
</code></pre></p>
<h3>文字列フォーマットの例</h3>
<p><div class="yata" id="72d5bbe833bc6525a1cdb737348a3ed6cc82593e"><div class="codehilite"><pre><span></span><code><span class="cp">#include <a href="../iostream.html"><iostream></a></span>
<span class="cp">#include <a href="../chrono.html"><chrono></a></span>
<span class="cp">#include <a href="../format.html"><format></a></span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">chrono</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="nn">std</span><span class="o">::</span><span class="nn">chrono</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="n"><a href="utc_clock.html">chrono::utc_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="utc_clock.html">chrono::utc_clock</a></span><span class="o">::</span><span class="n"><a href="utc_clock/now.html">now()</a></span><span class="p">;</span>
<span class="w"> </span><span class="n">chrono</span><span class="o">::</span><span class="n">utc_seconds</span><span class="w"> </span><span class="n">now_sec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n"><a href="time_point/floor.html">chrono::floor</a></span><span class="o"><</span><span class="n"><a href="duration_aliases.html">chrono::seconds</a></span><span class="o">></span><span class="p">(</span><span class="n">now</span><span class="p">);</span>
<span class="w"> </span><span class="c1">// デフォルトフォーマット</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"1 : {}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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="c1">// 「年月日 時分秒」のフォーマット</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"2 : {:%Y年%m月%d日 %H時%M分%S秒}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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="c1">// 日付を / (スラッシュ) 区切り、時間を : (コロン) 区切り、タイムゾーンの略称付き</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"3 : {0:%Y/%m/%d %H:%M:%S %Z}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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="c1">// 日付だけ出力</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"4 : {:%Y年%m月%d日}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"5 : {:%F}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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="c1">// 時間だけ出力</span>
<span class="w"> </span><span class="n"><a href="../iostream/cout.html">std::cout</a></span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"6 : {:%H時%M分%S秒}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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"><a href="format.html">std::format</a></span><span class="p">(</span><span class="s">"7 : {:%T}"</span><span class="p">,</span><span class="w"> </span><span class="n">now_sec</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>
<h4>出力例</h4>
<p><pre><code>1 : 2019-12-20 10:05:05
2 : 2019年12月20日 10時05分05秒
3 : 2019/12/20 10:05:05 UTC
4 : 2019年12月20日
5 : 2019-12-20
6 : 10時05分05秒
7 : 10:05:05
</code></pre></p>
<h2>バージョン</h2>
<h3>言語</h3>
<ul>
<li>C++20</li>
</ul>
<h3>処理系</h3>
<ul>
<li><a href="../../implementation.html#clang">Clang</a>: 9.0 <span aria-label="未実装" role="img" title="未実装">❌</span></li>
<li><a href="../../implementation.html#gcc">GCC</a>: 9.2 <span aria-label="未実装" role="img" title="未実装">❌</span>, 15.1 <span aria-label="検証済" role="img" title="検証済">✅</span></li>
<li><a href="../../implementation.html#visual_cpp">Visual C++</a>: 2019 Update 3 <span aria-label="未実装" role="img" title="未実装">❌</span></li>
</ul>
<h2>関連項目</h2>
<ul>
<li><a href="format.html">chronoの<code>std::format()</code></a> (出力フォーマットの詳細)</li>
<li><a href="parse.html">chronoの<code>parse()</code></a> (入力フォーマットの詳細)</li>
</ul>
<h2>参照</h2>
<ul>
<li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2117r0.html#3359" target="_blank">LWG Issue 3359. <code><chrono></code> leap second support should allow for negative leap seconds</a></li>
<li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2372r1.html" target="_blank">P2372R1 Fixing locale handling in chrono formatters</a><ul>
<li>この提案文書はC++20の策定後に採択されたが、実装が追いついていない時期の採択だったために、C++20の仕様として扱われる</li>
</ul>
</li>
</ul></div>
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