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Clarify is_leap_second

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Howard Hinnant
2018-03-23 09:29:19 -04:00
parent f4639bde96
commit c842fd0a19
1 changed files with 40 additions and 4 deletions
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tz.html
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@@ -2824,15 +2824,51 @@ is_leap_second(utc_time<Duration> const& t);
<blockquote> <blockquote>
<p> <p>
<i>Returns:</i> If <code>t</code> represents a <code>time_point</code> during a leap <i>Returns:</i> Given a list of leap second insertion dates <i>l<sub>i</sub></i> since
second insertion, the first member of the <code>pair</code> has a value of 1970-01-01,
if <code>t</code> is in the range [<i>l<sub>i</sub></i>, <i>l<sub>i</sub></i> + 1s),
the first member of the <code>pair</code> has a value of
<code>true</code>, otherwise <code>false</code>. The second member of the returned <code>true</code>, otherwise <code>false</code>. The second member of the returned
<code>pair</code> holds the number of leap seconds that have been inserted between <code>pair</code> holds the number of leap seconds that have been inserted between
<code>t</code> and 1970-01-01. If <code>t</code> represents a <code>time_point</code> <code>t</code> and 1970-01-01. If <code>t</code> represents a <code>time_point</code>
prior to 1970-01-01, the value is <code>0s</code>. If <code>t</code> represents a prior to 1970-01-01, the value is <code>0s</code>. If <code>t</code> is in the range
<code>time_point</code> during a leap second insertion, that full leap second is included [<i>l<sub>i</sub></i>, <i>l<sub>i</sub></i> + 1s), <i>l<sub>i</sub></i> is included
in the count. in the count.
</p> </p>
<p>
[<i>Example:</i>
</p>
<blockquote><pre>
cout &lt;&lt; boolalpha;
auto t = clock_cast&lt;utc_clock&gt;(sys_days{December/31/2016} + 23h + 59min + 59s + 999ms);
auto p = is_leap_second(t);
cout &lt;&lt; t &lt;&lt; " : {" &lt;&lt; p.first &lt;&lt; ", " &lt;&lt; p.second &lt;&lt; "}\n";
// 2016-12-31 23:59:59.999 : {false, 26s}
t += 1ms;
p = is_leap_second(t);
cout &lt;&lt; t &lt;&lt; " : {" &lt;&lt; p.first &lt;&lt; ", " &lt;&lt; p.second &lt;&lt; "}\n";
// 2016-12-31 23:59:60.000 : {true, 27s}
t += 1ms;
p = is_leap_second(t);
cout &lt;&lt; t &lt;&lt; " : {" &lt;&lt; p.first &lt;&lt; ", " &lt;&lt; p.second &lt;&lt; "}\n";
// 2016-12-31 23:59:60.001 : {true, 27s}
t += 998ms;
p = is_leap_second(t);
cout &lt;&lt; t &lt;&lt; " : {" &lt;&lt; p.first &lt;&lt; ", " &lt;&lt; p.second &lt;&lt; "}\n";
// 2016-12-31 23:59:60.999 : {true, 27s}
t += 1ms;
p = is_leap_second(t);
cout &lt;&lt; t &lt;&lt; " : {" &lt;&lt; p.first &lt;&lt; ", " &lt;&lt; p.second &lt;&lt; "}\n";
// 2017-01-01 00:00:00.000 : {false, 27s}
</pre></blockquote>
<p>
&mdash;<i>end example</i>]
</p>
</blockquote> </blockquote>
</blockquote> </blockquote>