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units/example/runtime_unit.cpp
Steven Watanabe ec80e73cad Finish runtime_unit.cpp example
[SVN r38866]
2007-08-23 18:03:38 +00:00

70 lines
2.6 KiB
C++

// mcs::units - A C++ library for zero-overhead dimensional analysis and
// unit/quantity manipulation and conversion
//
// Copyright (C) 2003-2007 Matthias Christian Schabel
// Copyright (C) 2007 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 <map>
#include <iostream>
#include <boost/lexical_cast.hpp>
#include <boost/units/quantity.hpp>
#include <boost/units/cmath.hpp>
#include <boost/units/systems/si/length.hpp>
#include <boost/units/systems/base_units.hpp>
//[runtime_unit_snippet_1
namespace {
std::map<std::string, boost::units::quantity<boost::units::SI::length> > known_units;
}
boost::units::quantity<boost::units::SI::length> calculate(const boost::units::quantity<boost::units::SI::length>& t) {
return(boost::units::hypot(t, 2.0 * boost::units::SI::meters));
}
int main() {
known_units["meter"] = 1.0 * boost::units::SI::meters;
known_units["centimeter"] = .01 * boost::units::SI::meters;;
known_units["foot"] = conversion_factor(boost::units::foot_base_unit::unit_type(), boost::units::SI::meter) * boost::units::SI::meters;;
std::string output_type("meter");
std::string input;
while(std::cin >> input) {
if(input == "exit") break;
else if(input == "help") {
std::cout << "type \"exit\" to exit\n"
"type \"return 'unit'\" to set the return units\n"
"type \"'number' 'unit'\" to do a simple calculation" << std::endl;
} else if(input == "return") {
if(std::cin >> input) {
if(known_units.find(input) != known_units.end()) {
output_type = input;
std::cout << "Done." << std::endl;
} else {
std::cout << "Unknown unit \"" << input << "\"" << std::endl;
}
} else break;
} else {
try {
double value = boost::lexical_cast<double>(input);
if(std::cin >> input) {
if(known_units.find(input) != known_units.end()) {
std::cout << static_cast<double>(calculate(value * known_units[input]) / known_units[output_type]) << ' ' << output_type << std::endl;
} else {
std::cout << "Unknown unit \"" << input << "\"" << std::endl;
}
} else break;
} catch(...) {
std::cout << "Input error" << std::endl;
}
}
}
}
//]