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