25 Time library [time]

25.7 Clocks [time.clock]

25.7.8 Local time [time.clock.local]

The family of time points denoted by local_time<Duration> are based on the pseudo clock local_t.

local_t has no member now() and thus does not meet the clock requirements.

Nevertheless local_time<Duration> serves the vital role of representing local time with respect to a not-yet-specified time zone.

Aside from being able to get the current time, the complete time_point algebra is available for local_time<Duration> (just as for sys_time<Duration>).

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template<class charT, class traits, class Duration>
  basic_ostream<charT, traits>&
    operator<<(basic_ostream<charT, traits>& os, const local_time<Duration>& lt);

Effects:

os << sys_time<Duration>{lt.time_since_epoch()};

Returns: os.

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template<class charT, class traits, class Duration>
  basic_ostream<charT, traits>&
    to_stream(basic_ostream<charT, traits>& os, const charT* fmt, const local_time<Duration>& tp,
              const string* abbrev = nullptr, const seconds* offset_sec = nullptr);

Effects: Streams tp into os using the format specified by the NTCTS fmt.

fmt encoding follows the rules specified in [time.format].

If %Z is used, it will be replaced with *abbrev if abbrev is not equal to nullptr.

If abbrev is equal to nullptr (and %Z is used), os.setstate(ios_base::failbit) shall be called.

If %z is used (or a modified variant of %z), it will be formatted with the value of *offset_sec if offset_sec is not equal to nullptr.

If %z (or a modified variant of %z) is used, and offset_sec is equal to nullptr, then os.setstate(ios_base::failbit) shall be called.

Returns: os.

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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,
                local_time<Duration>& tp, basic_string<charT, traits, Alloc>* abbrev = nullptr,
                minutes* offset = nullptr);

Effects: Attempts to parse the input stream is into the local_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.

Returns: is.