mp_units::value_cast

Synopsis

Declared in <mp-units/framework/value_cast.h>

template<
    typename ToRep,
    Unit auto ToU,
    typename FwdQ,
    RoundingPolicy Policy = truncated_t,
    Quantity Q = std::remove_cvref_t<FwdQ>>
requires UnitOf<MP_UNITS_REMOVE_CONST(decltype(ToU)), Q::quantity_spec> &&
           RepresentationOf<ToRep, Q::quantity_spec> && std::constructible_from<ToRep, typename Q::rep> &&
           detail::ExplicitlyCastable<Q::unit, ToU, ToRep> &&
           detail::ValidRoundingPolicyFor<Policy, typename Q::rep, ToRep>
[[nodiscard]]
constexpr
Quantity auto
value_cast(
    FwdQ&& q,
    Policy policy = Policy{});

Description

Implicit conversions between quantities of different types are allowed only for "safe" (e.g. non-truncating) conversion. In truncating cases an explicit cast have to be used.

auto q = value_cast<int, us>(1.23 * ms);

Return Value

the quantity converted to unit ToU and representation type ToRep

NOTE

The return value should not be discarded.

Template Parameters

Name	Description
ToRep	a representation type to use for the target quantity
ToU	a unit to use for the target quantity

Parameters

Name	Description
q	the quantity to cast
policy	an optional rounding policy (`truncated` when not provided)