27 Time library [time]

27.7 Clocks [time.clock]

27.7.2 Class utc_­clock [time.clock.utc]

27.7.2.3 Non-member functions [time.clock.utc.nonmembers]

template<class charT, class traits, class Duration> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const utc_time<Duration>& t);
Effects: Equivalent to:
return os << format(STATICALLY-WIDEN<charT>("{:%F %T}"), t);
Example
:
auto t = sys_days{July/1/2015} - 500ms;
auto u = clock_cast<utc_clock>(t);
for (auto i = 0; i < 8; ++i, u += 250ms)
  cout << u << " UTC\n";
Produces this output:
2015-06-30 23:59:59.500 UTC
2015-06-30 23:59:59.750 UTC
2015-06-30 23:59:60.000 UTC
2015-06-30 23:59:60.250 UTC
2015-06-30 23:59:60.500 UTC
2015-06-30 23:59:60.750 UTC
2015-07-01 00:00:00.000 UTC
2015-07-01 00:00:00.250 UTC
— end example
 ]
template<class charT, class traits, class Duration, class Alloc = allocator<charT>> basic_istream<charT, traits>& from_stream(basic_istream<charT, traits>& is, const charT* fmt, utc_time<Duration>& tp, basic_string<charT, traits, Alloc>* abbrev = nullptr, minutes* offset = nullptr);
Effects: Attempts to parse the input stream is into the utc_­time tp using the format flags given in the NTCTS fmt as specified in [time.parse].
If the parse fails to decode a valid date, is.setstate(ios_­base​::​failbit) shall be called and tp shall not be modified.
If %Z is used and successfully parsed, that value will be assigned to *abbrev if abbrev is non-null.
If %z (or a modified variant) is used and successfully parsed, that value will be assigned to *offset if offset is non-null.
Additionally, the parsed offset will be subtracted from the successfully parsed timestamp prior to assigning that difference to tp.
Returns: is.
struct leap_second_info { bool is_leap_second; seconds elapsed; };
The type leap_­second_­info has data members and special members specified above.
It has no base classes or members other than those specified.
template<class Duration> leap_second_info get_leap_second_info(const utc_time<Duration>& ut);
Returns: A leap_­second_­info where is_­leap_­second is true if ut is during a leap second insertion, and otherwise false.
elapsed is the number of leap seconds between 1970-01-01 and ut.
If is_­leap_­second is true, the leap second referred to by ut is included in the count.