29 Time library [time]

29.9 Class template hh_mm_ss [time.hms]

29.9.2 Members [time.hms.members]

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

Table 100: 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().
(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.

🔗

constexpr explicit operator precision() const noexcept;

Returns: to_duration().