{

known_units["meter"] = 1.0 * si::meters;

known_units["centimeter"] = .01 * si::meters;

known_units["foot"] =

conversion_factor(foot_base_unit::unit_type(), si::meter) * si::meter;

std::string output_type("meter");

std::string input;

while((std::cout << "> ") && (std::cin >> input))

{

if(!input.empty() && input[0] == '#')

{

std::getline(std::cin, input);

}

else 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;

}

}

}