mp-units/example/hello_units.cpp

// The MIT License (MIT)
//
// Copyright (c) 2018 Mateusz Pusz
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include <units/format.h>
#include <units/isq/space_and_time.h>
#include <units/quantity_io.h>
#include <units/si/international/length.h>
#include <units/si/international/speed.h>
#include <units/si/unit_symbols.h>
#include <iostream>

using namespace units;

constexpr quantity_of<isq::speed> auto avg_speed(quantity_of<isq::length> auto d, quantity_of<isq::time> auto t)
{
  return quantity_cast<isq::speed>(d / t);
}

int main()
{
  using namespace units::si::unit_symbols;
  using namespace units::si::international::unit_symbols;

  constexpr auto v1 = 110 * isq::speed[km / h];
  constexpr auto v2 = 70. * isq::speed[mph];
  constexpr auto v3 = avg_speed(220 * isq::length[km], 2 * isq::time[h]);
  constexpr auto v4 = avg_speed(quantity<isq::length[mi]>{140}, quantity<isq::time[h]>{2});
  constexpr auto v5 = quantity_cast<quantity<isq::speed[m / s]>>(v3);
  constexpr auto v6 = quantity_cast<m / s>(v4);
  constexpr auto v7 = quantity_cast<int>(v6);

  std::cout << v1 << '\n';                                       // 110 km/h
  std::cout << v2 << '\n';                                       // 70 mi/h
  std::cout << STD_FMT::format("{}", v3) << '\n';                // 110 km/h
  std::cout << STD_FMT::format("{:*^14}", v4) << '\n';           // ***70 mi/h****
  std::cout << STD_FMT::format("{:%Q in %q}", v5) << '\n';       // 30.5556 in m/s
  std::cout << STD_FMT::format("{0:%Q} in {0:%q}", v6) << '\n';  // 31.2928 in m/s
  std::cout << STD_FMT::format("{:%Q}", v7) << '\n';             // 31
}