forked from mpusz/mp-units
64 lines
2.3 KiB
C++
64 lines
2.3 KiB
C++
/*
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Copyright (c) 2003-2020 Andy Little.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see http://www.gnu.org/licenses./
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*/
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#include "./units_str.h"
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#include "./length.h"
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#include <units/quantity_io.h>
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#include <iostream>
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/*
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get conversion factor from one dimensionally equivalent
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quantity type to another
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*/
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namespace {
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template<units::Quantity Target, units::Quantity Source>
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requires units::equivalent<typename Source::dimension, typename Target::dimension>
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inline constexpr std::common_type_t<typename Target::rep, typename Source::rep> conversion_factor(Target, Source)
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{
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// get quantities looking like inputs but with Q::rep that doesn't have narrowing conversion
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typedef std::common_type_t<typename Target::rep, typename Source::rep> rep;
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typedef units::quantity<typename Source::dimension, typename Source::unit, rep> source;
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typedef units::quantity<typename Target::dimension, typename Target::unit, rep> target;
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return target{source{1}}.number();
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}
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} // namespace
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using namespace units::isq::si::literals;
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using namespace units::experimental;
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int main()
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{
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std::cout << "conversion factor in mpusz/units...\n\n";
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constexpr length::m<> lengthA = 2.0_q_m;
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constexpr length::mm<> lengthB = lengthA;
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std::cout << "lengthA( " << lengthA << " ) and lengthB( " << lengthB << " )\n"
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<< "represent the same length in different units.\n\n";
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std::cout << "therefore ratio lengthA / lengthB == " << lengthA / lengthB << "\n\n";
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std::cout << "conversion factor from lengthA::unit of "
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<< units_str(lengthA).standard() << " to lengthB::unit of " << units_str(lengthB).standard() << " :\n\n"
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<< "lengthB.number( " << lengthB.number() << " ) == lengthA.number( " << lengthA.number()
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<< " ) * conversion_factor( " << conversion_factor(lengthB, lengthA) << " )\n";
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}
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