27 Time library [time]

27.9 Class template hh_­mm_­ss [time.hms]

27.9.2 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
:
See Table 96 for some durations, the resulting fractional_­width, and the formatted fractional second output of Duration{1}.
Table 96: 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
 ]
using precision = see below;
precision is
duration<common_type_t<Duration::rep, seconds::rep>, ratio<1, >>
constexpr explicit hh_mm_ss(Duration d);
Effects: Constructs an object of type hh_­mm_­ss which represents the Duration d with precision precision.
  • Initializes is_­neg with d < Duration​::​zero().
  • Initializes h with duration_­cast<chrono​::​hours>(abs(d)).
  • Initializes m with duration_­cast<chrono​::​minutes>(abs(d) - hours()).
  • Initializes s with duration_­cast<chrono​::​seconds>(abs(d) - hours() - minutes()).
  • 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
:
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).
constexpr bool is_negative() const noexcept;
Returns: is_­neg.
constexpr chrono::hours hours() const noexcept;
Returns: h.
constexpr chrono::minutes minutes() const noexcept;
Returns: m.
constexpr chrono::seconds seconds() const noexcept;
Returns: s.
constexpr precision subseconds() const noexcept;
Returns: ss.
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().