std::chrono::duration<Rep,Period>::duration - cppreference.com (original) (raw)

constexpr duration() = default; (1) (since C++11)
duration( const duration& ) = default; (2) (since C++11)
template< class Rep2 > constexpr explicit duration( const Rep2& r ); (3) (since C++11)
template< class Rep2, class Period2 > constexpr duration( const duration<Rep2, Period2>& d ); (4) (since C++11)

Constructs a new duration from one of several optional data sources.

  1. The default constructor.

  2. The copy constructor.

  3. Constructs a duration with r ticks.

  4. Constructs a duration by converting d to an appropriate period and tick count, as if by std::chrono::duration_cast<duration>(d).count().

  1. ↑ That is, a duration with an integer tick count cannot be constructed from a floating-point value, but a duration with a floating-point tick count can be constructed from an integer value.
  2. ↑ That is, either the duration uses floating-point ticks, or Period2 is exactly divisible by Period.

[edit] Parameters

r - a tick count
d - a duration to copy from

[edit] Example

The following code shows several examples (both valid and invalid) of how to construct durations:

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2094 C++11 for overload (4), std::ratio_divide<Period2, period>::nummight overflow when evaluatingstd::ratio_divide<Period2, period>::den overload (4) does notparticipate in overloadresolution in this case
LWG 3050 C++11 convertibility constraint used non-const xvalue use const lvalues instead

[edit] See also