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// Boost.Units - A C++ library for zero-overhead dimensional analysis and
// unit/quantity manipulation and conversion
//
// Copyright (C) 2003-2008 Matthias Christian Schabel
// Copyright (C) 2008 Steven Watanabe
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#include <boost/units/base_dimension.hpp>
#include <boost/units/base_unit.hpp>
#include <boost/units/unit.hpp>
#include <boost/units/quantity.hpp>
//[runtime_conversion_factor_snippet_1
using boost::units::base_dimension;
using boost::units::base_unit;
static const long currency_base = 1;
struct currency_base_dimension : base_dimension<currency_base_dimension, 1> {};
typedef currency_base_dimension::dimension_type currency_type;
template<long N>
struct currency_base_unit :
base_unit<currency_base_unit<N>, currency_type, currency_base + N> {};
typedef currency_base_unit<0> us_dollar_base_unit;
typedef currency_base_unit<1> euro_base_unit;
typedef us_dollar_base_unit::unit_type us_dollar;
typedef euro_base_unit::unit_type euro;
// an array of all possible conversions
double conversion_factors[2][2] = {
{1.0, 1.0},
{1.0, 1.0}
};
double get_conversion_factor(long from, long to) {
return(conversion_factors[from][to]);
}
void set_conversion_factor(long from, long to, double value) {
conversion_factors[from][to] = value;
conversion_factors[to][from] = 1.0 / value;
}
BOOST_UNITS_DEFINE_CONVERSION_FACTOR_TEMPLATE((long N1)(long N2),
currency_base_unit<N1>,
currency_base_unit<N2>,
double, get_conversion_factor(N1, N2));
//]
int main() {
boost::units::quantity<us_dollar> dollars = 2.00 * us_dollar();
boost::units::quantity<euro> euros(dollars);
set_conversion_factor(0, 1, 2.0);
dollars = static_cast<boost::units::quantity<us_dollar> >(euros);
set_conversion_factor(0, 1, .5);
euros = static_cast<boost::units::quantity<euro> >(dollars);
double value = euros.value(); // = .5
if(value != .5) {
return(1);
} else {
return(0);
}
}
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