[time.hms]

The hh_mm_ss class template splits a duration into a multi-field time structure hours:minutes:seconds and possibly subseconds, where subseconds will be a duration unit based on a non-positive power of 10.

The Duration template parameter dictates the precision to which the time is split.

A hh_mm_ss models negative durations with a distinct is_negative getter that returns true when the input duration is negative.

The individual duration fields always return non-negative durations even when is_negative() indicates the structure is representing a negative duration.

If Duration is not a specialization of duration, the program is ill-formed.

30.9.2 Members [time.hms.members]

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static constexpr unsigned fractional_width = see below;

fractional_width is the number of fractional decimal digits represented by precision.

fractional_width has the value of the smallest possible integer in the range [0, 18] such that precision will exactly represent all values of Duration.

If no such value of fractional_width exists, then fractional_width is 6.

[Example 1:

See Table 132 for some durations, the resulting fractional_width, and the formatted fractional second output of Duration{1}.

Table 132 — Examples for fractional_width [tab:time.hms.width]

🔗 Duration	fractional_width	Formatted fractional second output
🔗 hours, minutes, and seconds	0
🔗 milliseconds	3	0.001
🔗 microseconds	6	0.000001
🔗 nanoseconds	9	0.000000001
🔗 duration<int, ratio<1, 2>	1	0.5
🔗 duration<int, ratio<1, 3>	6	0.333333
🔗 duration<int, ratio<1, 4>	2	0.25
🔗 duration<int, ratio<1, 5>	1	0.2
🔗 duration<int, ratio<1, 6>	6	0.166666
🔗 duration<int, ratio<1, 7>	6	0.142857
🔗 duration<int, ratio<1, 8>	3	0.125
🔗 duration<int, ratio<1, 9>	6	0.111111
🔗 duration<int, ratio<1, 10>	1	0.1
🔗 duration<int, ratio<756, 625>	4	0.2096

— end example]

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using precision = see below;

precision is duration<common_type_t<Duration::rep, seconds::rep>, ratio<1,

10fractional_width>

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constexpr explicit hh_mm_ss(Duration d);

Effects: Constructs an object of type hh_mm_ss which represents the Duration d with precision precision.

(3.1)
Initializes is_neg with d < Duration::zero().

Let ABS_D represent -d if is_neg is true and d otherwise.
(3.2)
Initializes h with duration_cast<chrono::hours>(ABS_D).
(3.3)
Initializes m with duration_cast<chrono::minutes>(ABS_D - hours().
(3.4)
Initializes s with duration_cast<chrono::seconds>(ABS_D - hours() - minutes().
(3.5)
If treat_as_floating_point_v<precision::rep> is true, initializes ss with ABS_D - hours() - minutes() - seconds().

Otherwise, initializes ss with duration_cast<precision>(ABS_D - hours() - minutes() - seconds().

[Note 1:

When precision::rep is integral and precision::period is ratio<1>, subseconds() always returns a value equal to 0s.

— end note]

Postconditions: If treat_as_floating_point_v<precision::rep> is true, to_duration() returns d, otherwise to_duration() returns duration_cast<precision>(d).

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constexpr bool is_negative() const noexcept;

Returns: is_neg.

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constexpr chrono::hours hours() const noexcept;

Returns: h.

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constexpr chrono::minutes minutes() const noexcept;

Returns: m.

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constexpr chrono::seconds seconds() const noexcept;

Returns: s.

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constexpr precision subseconds() const noexcept;

Returns: ss.

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constexpr precision to_duration() const noexcept;

Returns: If is_neg, returns -(h + m + s + ss), otherwise returns h + m + s + ss.

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constexpr explicit operator precision() const noexcept;

Returns: to_duration().

30.9.3 Non-members [time.hms.nonmembers]

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

Effects: Equivalent to: return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{:L%T}"), hms);

[Example 1: for (auto ms : {-4083007ms, 4083007ms, 65745123ms}) { hh_mm_ss hms{ms}; cout << hms << '\n'; } cout << hh_mm_ss{65745s} << '\n';

Produces the output (assuming the "C" locale): -01:08:03.007 01:08:03.007 18:15:45.123 18:15:45

— end example]

30 Time library [time]

30.9 Class template hh_mm_ss [time.hms]

30.9.1 Overview [time.hms.overview]

30.9.2 Members [time.hms.members]

30.9.3 Non-members [time.hms.nonmembers]

30.9.1 Overview [time.hms.overview]

30.9.2 Members [time.hms.members]

30.9.3 Non-members [time.hms.nonmembers]